JICA報告書PDF版(JICA Report PDF) - JAPAN ...Reflecting on the history of railway development in Japan, it is noted that Japan has indeed a great deal of experience in the planning,

JAPAN INTERNATIONAL COOPERATION AGENCY (JICA)

VIETNAM RAILWAYS (VR)

STUDY FOR THE FORMULATION OF HIGH SPEED RAILWAY

PROJECTS ON HANOI – VINH AND HO CHI MINH – NHA TRANG

SECTION

FINAL REPORT

TECHNICAL REPORT 5

GEOLOGICAL SURVEY AND PREPARATION OF TOPOGRAPHIC

MAP

June 2013

ALMEC CORPORATION

JAPAN INTERNATIONAL CONSULTANTS FOR TRANSPORTATION CO., LTD.

ORIENTAL CONSULTANTS CO., LTD.

NIPPON KOEI CO., LTD.

JAPAN TRANSPORTATION CONSULTANTS, INC. E I

J R

1 3 - 1 7 8

Exchange rate used in the Report

USD 1 = JPY 78 = VND 21,000

(Based on rate on November 2011)

PREFACE

In response to the request from the Government of the Socialist Republic of Vietnam, the

Government of Japan decided to conduct the Study for the Formulation of High Speed Railway

Projects on Hanoi – Vinh and Ho Chi Minh – Nha Trang Section and entrusted the program to

the Japan International cooperation Agency (JICA).

JICA dispatched a team to Vietnam between April 2011 and June 2013, which was headed

by Mr. IWATA Shizuo of ALMEC Corporation and consisted of ALMEC Corporation, Japan

International Consultants for Transportation Co., Ltd., Oriental Consultants Co., Ltd., Nippon

Koei Co., Ltd. and Japan Transportation Consultants, Inc.

In the cooperation with the Vietnamese Counterpart Team including the Ministry of

Transport and Vietnam Railways, the JICA Study Team conducted the study which includes

traffic demand analysis, natural and socio-economic conditions, alignment planning,

consideration of various options including the upgrading of existing railway, technical

standards for high speed railway, implementation schedule and institutions, and human

resource development. It also held a series of discussions with the relevant officials of the

Government of Vietnam. Upon returning to Japan, the Team duly finalized the study and

delivered this report in June 2013.

Reflecting on the history of railway development in Japan, it is noted that Japan has indeed

a great deal of experience in the planning, construction, operation, etc., and it is deemed that

such experiences will greatly contribute to the railway development in Vietnam. JICA is

willing to provide further cooperation to Vietnam to achieve sustainable development of railway

sector and to enhance friendly relationship between the two countries.

It is hoped that this report will contribute to the sustainable development of transport

system in Vietnam and to the enhancement of friendly relations between the two countries.

Finally, I wish to express my sincere appreciation to the officials of the Government of

Vietnam for their close cooperation.

June 2013

Kazuki Miura

Director, Economic Infrastructure Department

Japan International Cooperation Agency

i

TABLE OF CONTENTS

1 GENERAL GEOLOGICAL INFORMATION OF VIETNAM ......................................... 1-1

2 GEOLOGICAL SURVEY FOR NORTH SECTION ...................................................... 2-1

2.1 Outline of Soil Structures, Topography and Geology .......................................................... 2-1

2.2 Boring Investigation .......................................................................................................... 2-13

2.3 Discussion on Results of Boring Investigation and Soil Testing: North Section ................ 2-34

3 GEOLOGICAL SURVEY FOR SOUTH SECTION ....................................................... 3-1

3.1 Site Survey in South Section .............................................................................................. 3-1

3.2 Boring Investigation ............................................................................................................ 3-8

4 CONSIDERATIONS FOR TUNNELS ALONG HSR ALIGNMENT .............................. 4-1

4.1 General ............................................................................................................................... 4-1

4.2 Design for Tunnel ............................................................................................................... 4-2

4.3 Rock Classification of Tunnels ........................................................................................... 4-4

4.4 Tunnel Construction Method .............................................................................................. 4-8

4.5 Tunnel Portal Design ........................................................................................................ 4-11

4.6 Standard Support System for the HSR Tunnels ............................................................... 4-14

4.7 Monitoring ......................................................................................................................... 4-17

5 PREPARATION FOR TOPOGRAPHIC MAP .............................................................. 5-1

5.1 General ............................................................................................................................... 5-1

5.2 Methodology ....................................................................................................................... 5-1

ii

LIST OF TABLES Table 2.1.1 List of Soil Structures, Land use and Comments on Topography & Geology ................ 2-2

Table 2.1.2 Details of Tunnels: The North Section of the HSR Route .............................................. 2-3

Table 2.2.1 Variation of the Field Investigation and the Regulations Used ..................................... 2-13

Table 2.2.2 Location, Depth of the Borehole Tests and Number of the SPT .................................. 2-14

Table 2.2.3 Total Quantity of Investigation ...................................................................................... 2-17

Table 2.2.4 (1) Summary of Soil Testing; Br-1 and Br-4 ................................................................. 2-23

Table 2.2.5 (2) Summary of Soil Testing; Br-6 and Br-8 ................................................................. 2-24

Table 2.2.6 (3) Summary of Soil Testing; Br-9 and Br-12 ............................................................... 2-25

Table 2.2.7 (4) Summary of Soil Testing; Br-13 .............................................................................. 2-26

Table 2.3.1 List of Layers of Very Soft Clay, Sensitive Clay and Condition of Consolidation ......... 2-35

Table 2.3.2 Physical Properties and Parameters of the Cv and Cc ................................................ 2-39

Table 2.3.3 (1) Trial Calculation of Settlement for a 6 m Height Embankment ............................... 2-39

Table 2.3.4 (2) Trial Calculation of Settlement for a 9 m Height Embankment ............................... 2-39

Table 2.3.5 Settlement Due to Embankment .................................................................................. 2-40

Table 2.3.6 Estimation of Cv ........................................................................................................... 2-41

Table 2.3.7 Tv for each εf ................................................................................................................ 2-41

Table 2.3.8 Trial calculation of settlement using the sand drain method ........................................ 2-42

Table 3.1.1 Typical Geology from HCMC to Nha Trang .................................................................... 3-1

Table 3.2.1 List of Boring Locations along HSR Route in South Section .......................................... 3-8

Table 3.2.2 Result of Soil Test (Atterberg Limit) at BH1 ................................................................. 3-11

Table 3.2.3 Result of Consolidation Test at BH1 ............................................................................ 3-11






Table 3.2.9 Result of Soil Test (Atterberg Limit) at BH5, 5A, 5B .................................................... 3-22

Table 3.2.10 Result of Soil Test (Atterberg Limit) at BH6 ................................................................ 3-24

Table 3.2.11 T.C.R. & R.Q.D. of Boring No.7 ................................................................................... 3-26



Table 3.2.14 Result of Consolidation Test at BH9 ........................................................................... 3-29

Table 3.2.15 Result of Soil Test (Atterberg Limit) at BH10 .............................................................. 3-31

Table 3.2.16 Result of Consolidation Test at BH10 ......................................................................... 3-31

Table 3.2.17 Classification for Cohesive Soil ................................................................................... 3-32

Table 3.2.18 Classification for Cohesionless Soil ............................................................................ 3-32

Table 3.2.19 Basic Soil Groups Used in Boring Investigation .......................................................... 3-33

Table 3.2.20 Soil Testing Results in South Section (HCMC–Nha Trang Section) (1/4) .................. 3-49




Table 4.1.1 Advantage and Disadvantage of Tunnels ..................................................................... 4-1

iii

Table 4.2.1 Shinkansen (Bullet Railway) Tunnels Completed in 2010 (Length > 2,000 m) ............. 4-3

Table 4.3.1 Rock Classification in Hai Van Pass Tunnel ................................................................. 4-6

Table 4.3.2 Rock Type and Classification for Railway in Japan ...................................................... 4-7

Table 4.4.1 Tunnel Driving Method .................................................................................................. 4-8

Table 4.4.2 Tunnel Excavation Method ............................................................................................ 4-9

Table 4.5.1 Remarkable Points for Determination of the Tunnel Portal ......................................... 4-11

Table 4.5.2 Tunnel Entrance Structure .......................................................................................... 4-13

Table 4.6.1 Standard Support Pattern of HSR Tunnel ................................................................... 4-14

Table 4.6.2 Support System for Shikansen Tunnels ...................................................................... 4-14

Table 4.6.3 Tunnel Location from Hanoi to Vinh ............................................................................ 4-15

Table 4.6.4 Tunnel location from HCMC to Nha Trang .................................................................. 4-16

Table 4.7.1 Daily Observation Chart .............................................................................................. 4-18

Table 5.2.1 List of ALOS Purchased ................................................................................................ 5-1

LIST OF FIGURES Figure 1.1 Geology Map and the Planed HSR Routes................................................................... 1-2

Figure 1.2 Distribution of Faults and Folding on Indochina Block .................................................. 1-3

Figure 1.3 Typical Geological Cross Section near Ha Noi ............................................................. 1-3

Figure 1.4 Geological Cross Section of the Ba Lat Delta near Nam Dinh...................................... 1-4

Figure 1.5 Typical Geological Cross Section of Dalat Strungrng ................................................... 1-5

Figure 2.1.1 Geology and the HSR Route from Ngoc Hoi to Nam Dinh ........................................... 2-4

Figure 2.1.2 Construction Site of the Ngoc Hoi Station (Ngoc Hoi) .................................................. 2-5

Figure 2.1.3 Vast Rice Field in the Song Hong Delta (Ngoc Hoi–Phu Ly) ........................................ 2-5

Figure 2.1.4 Land Use in Suburbs of Nam Dinh ................................................................................ 2-6

Figure 2.1.5 Extensive Rice Field (Nam Dinh –Ninh Binh)................................................................ 2-6

Figure 2.1.6 Song Day river (Ninh Binh)............................................................................................ 2-7

Figure 2.1.7 Geology and the HSR Route Nam Dinh to Thanh Hoa ................................................. 2-8

Figure 2.1.8 Limestone Mountains near Location of Tunnel-1 .......................................................... 2-8

Figure 2.1.9 Scenery of the Song Ma River (Thanh Hoa) ................................................................. 2-9

Figure 2.1.10 Geology and the HSR Route from Thanh Hoa to P-7 (Tho Truong) ........................... 2-10

Figure 2.1.11 Geology and the HSR Route from P-7 (Tho Truong) to Vinh ..................................... 2-11

Figure 2.1.12 Mountains of Tunnel-5 & 6 and Typical Land Use (P-6–P-7) ..................................... 2-11

Figure 2.1.13 Limestone Mountains near Truong Lam (P-6–P-7) ..................................................... 2-12

Figure 2.1.14 Construction Site of the Depo for the HSR (Vinh) ....................................................... 2-12

Figure 2.1.15 Mountain for Tunnel-8 and Geology of a Cut Slope (P-7–Vinh) ................................. 2-12

Figure 2.2.1 Locations of Boreholes were Selected by JICA’s Engineer and TRICC’s

Engineer Determined in the Field ....................................................................................................... 2-14

Figure 2.2.2 Drilling of Br.1 .............................................................................................................. 2-15





Figure 2.2.7 Drilling of Br.12 ............................................................................................................ 2-15

iv

Figure 2.2.8 Drilling of Br.13 ............................................................................................................ 2-15

Figure 2.2.9 Samples in Stainless Steel Casings ( Br-4) ............................................................... 2-15

Figure 2.2.10 Thin Wall Tube Sampler Used .................................................................................... 2-16

Figure 2.2.11 Geological Longitudinal Section in the Ha Noi Area (After Geology Map of VN)........ 2-18

Figure 2.2.12 Geological Section in Thanh Hoa Region ................................................................... 2-20

Figure 2.2.13 Boring Log; Br-1 .......................................................................................................... 2-27





Figure 2.2.18 Boring Log; Br-12 ........................................................................................................ 2-32

Figure 2.2.19 Boring Log; Br-13 ........................................................................................................ 2-33

Figure 2.3.1 Geological Map and the Alignment of New HSR: North Section ............................... 2-34

Figure 2.3.2 Relationships of Cc against WL (North Part) ............................................................. 2-37

Figure 2.3.3 Relationships of Cv against WL (North Part) .............................................................. 2-37

Figure 2.3.4 Relationships of CS against CC (North Part) .............................................................. 2-37

Figure 2.3.5 Relationships of PC against depth (North Part) .......................................................... 2-37

Figure 2.3.6 Boring Log and Physical Properties: Br-1 ................................................................... 2-43





Figure 2.3.11 Boring Log and Physical Properties: Br-12 ................................................................. 2-45

Figure 2.3.12 Boring Log and Physical Properties: Br-13 ................................................................. 2-46

Figure 3.1.1 Geological Conditions in Thu Thiem–Dong Nai River Area .......................................... 3-4

Figure 3.1.2 Geological Conditions near LTIA Area .......................................................................... 3-4

Figure 3.1.3 Geological Conditions in Phan Thiet–Phan Ri Cua Area .............................................. 3-5

Figure 3.1.4 Geological Conditions near Ca Na Area ....................................................................... 3-6

Figure 3.1.5 Geological Conditions in Nha Trang ............................................................................. 3-7

Figure 3.2.1 Geological Map and Location of Boring ........................................................................ 3-9

Figure 3.2.2 Boring Location in Thu Thiem Station Area ................................................................ 3-10

Figure 3.2.3 Boring Location in HCMC Depot Location .................................................................. 3-12

Figure 3.2.4 Boring Location in LTIA Area ...................................................................................... 3-14

Figure 3.2.5 Boring Location in White Sand Area near Phan Thiet ................................................ 3-15

Figure 3.2.6 Boring Location at Phan Thiet Existing Line New Station ........................................... 3-17

Figure 3.2.7 Boring Location on the Bank of Ca Ty River ............................................................... 3-18

Figure 3.2.8 Crossing Point Location of HSR and Ca Ty River ...................................................... 3-19

Figure 3.2.9 Boring Location of No. 5, 5A, 5B ................................................................................. 3-20

Figure 3.2.10 Rhyolite Mountain Utilized as the Quarry Site near NH1A .......................................... 3-21

Figure 3.2.11 Location of BH5, 5A, 5B and the Alternative Routes .................................................. 3-21

Figure 3.2.12 Boring Location No 6 and White Sand Area near Tuy Phong..................................... 3-23

Figure 3.2.13 Boring Location for South Portal of Tunnel in Ca Na .................................................. 3-24

Figure 3.2.14 Boring Location No. 7 and Loose Sand in Salt Farm in Ca Na ................................... 3-25

Figure 3.2.15 Boring Location in Thap Cham Station Location ......................................................... 3-27

v

Figure 3.2.16 Boring Location in Nha Trang Station Location .......................................................... 3-28

Figure 3.2.17 Boring Location in HCMC Depot Location .................................................................. 3-30

Figure 3.2.18 Boring No 1 ................................................................................................................. 3-34

Figure 3.2.19 Boring No 2 ................................................................................................................. 3-35

Figure 3.2.20 Boring No 2A ............................................................................................................... 3-36

Figure 3.2.21 Boring No 3 ................................................................................................................. 3-37


Figure 3.2.23 Boring No 4 ................................................................................................................. 3-39

Figure 3.2.24 Boring No 5 ................................................................................................................. 3-40


Figure 3.2.26 Boring No 5B ............................................................................................................... 3-42

Figure 3.2.27 Boring No 6 ................................................................................................................. 3-43


Figure 3.2.29 Boring No 7 ................................................................................................................. 3-45

Figure 3.2.30 Boring No 8 ................................................................................................................. 3-46

Figure 3.2.31 Boring No 9 ................................................................................................................. 3-47

Figure 3.2.32 Boring No 10 ............................................................................................................... 3-48

Figure 4.2.1 Standard Cross Section of Tunnel for HSR .................................................................. 4-3

Figure 4.3.1 System (Revised in 2002) ............................................................................................. 4-4

Figure 4.3.2 Rock Mass Rating ......................................................................................................... 4-5

Figure 4.5.1 Area of Standard Portal Zone (Highway Tunnel) ........................................................ 4-12

Figure 5.2.1 Mapping Area (North) (The Shaded Portion) ................................................................ 5-3

Figure 5.2.2 Mapping Area (South) (The Shaded Portion) ............................................................... 5-4

ABBREVIATIONS

ALOS Advanced Land Oberving Satellite ASRRSZ Ailaoshn Suture-Red River Share Zone ASTM American Society of Testing and Materials HCMC Ho Chi Minh City HSR High Speed Railway JICA Japan International Cooperation Agency JIS Japanese Industrial Standard LTIA Long Thanh International Airport NATM New Austrian Tunneling Method RQD Rock Quality Designation SPT Standard Penetration Test TCR Total Core Recovery TOR Terms of Reference TRICC Transport Investment And Construction Consultant Joint

Stock Company

Study for the Formulation of High Speed Railway Projects on Hanoi–Vinh and Ho Chi Minh–Nha Trang Sections FINAL REPORT

Technical Report 5 Geological Survey and Preparation of Topographic Map

1-1

1 GENERAL GEOLOGICAL INFORMATION OF VIETNAM

1.1 The main land of Vietnam, a South-east Asian country, is located in the south-eastern part of the Indochina peninsula on the Eurasian continental block. The land, covers an area of approximately 325 km2 and extends from 8°30'N to 23°30' N latitude, a distance of more than 1600 km between its northern border along southern China to the southern-most border near Cape Camau. The eastern to western part of the country is variable with the widest part measuring 600 km in the north of Vietnam and the narrowest part measuring 40 km at Quang Vinh Province adjacent to Laos, where the Annamite mountain chain stretches along with the Den Dinh, Sam Sao, Hua Phan and, Truong Son Ridges.

1.2 Geological topography of the Eastern Indochina block, where Vietnamese land is situated along the southern margin of the peninsula, was formed due to orogenetic movements during the Cambrian to the Triassic periods (500–190Ma). The basement rocks are composed mainly of Archean gneiss, Cambrian gneiss and granite.

1.3 During the "Hercynian" orogenetic movements in the Carboniferous period (370–300Ma), so-called "Kon Tum massif" was formed due to uplifting of the middle part of Eastern Indochina block (ca. latitude 15°N–13°N, roughly from Hue to Nha Trang). Large mountain ranges and dissected plateaux of varying elevations were formed over wide areas of the middle part of Vietnam. In the southern part of the Kon Tum massif, along the faults bordering these dissected plateaux magmatic intrusions and basalt flows occurred in the late Paleozoic period (300Ma). Geology of the area was composed of basalt, granite and rocks originating from marine or continental sediment, such as sand stone, silt stone, conglomerate and lime stone.

1.4 In the northern area surrounding the Kon Tum massif (a section of the planned HSR route from Nam Dinh to Dong Hoi via Vinh City), the "Annamitic Folding" was formed due to the Hercynian orogenetic movements in the middle Paleozoic period (350–300Ma; see Figure 1.1 & Figure 1.2). In this area, thick diluvial deposits of the Pleistocene and alluvial deposits in the Holocene became sedimented on bed rocks composed of sand stone, silt stone conglomerate, lime stone, basalt, gneiss etc., which have been denuded due to hydraulic and glacial erosion.

1.5 In the adjacent northern area of the Annamitic Folding from Nam Dinh to Ngoc Hoi in the HSR route, the Song Hong River, with a length of 1,170 km and catchment area of 155,000 km2, forms an extended triangular Delta. The river is meandering with a gradient of 0.059 m/km from the north-west to the south-east along the Ailaoshn Suture-Red River Share Zone (the ASRRSZ). The river branches into a number of distributaries and discharges into the Gulf of Tonkin. It is assumed that the most downstream 23 km of the Da Lat Delta plain was formed in the last 500 years, with an average seaward growth of about 5 km/century due to an enormous amount of transported sand and silt by the river.

Study for the Formulation of High Speed Railway Projects on Hanoi–Vinh and Ho Chi Minh–Nha Trang Sections FINAL REPORT Technical Report 5 Geological Survey and Preparation of Topographic Map

1-2

Ha Noi

Ngoc Hoi

Truong Lam

Phu Ly

Nam Dinh

Ninh Binh

Thanh Hoa

Vinh

Surficial geology:

Yellow = Quaternary

(1) North section (Ngoc Hoi to Vinh)

(2) South section (Nha Trang to HCM)

Source: JICA Study Team.

Figure 1.1 Geology Map and the Planed HSR Routes



1-3

★Ha Noi

●

Nam

Dinh

Vinh

●

ASRRSZ=the Ailao Shan-RedRiver shear zone／ASCC = Ailao ShanCore Complex ／ DCS = DianChang Shan Core Complex ／

DNCV = Day Nui Con Voi CoreComplex／XLS = Xuc Long ShanCore Complex／THFZ=Tuy HoaFault Zone,

Metamorphic core complex

Approximate area of basin

Oceanic crust

Main Cenozoic strike‐slip direction

Subduction zone

Major thrust fault

Extensional fault system

Fault systems

Source: M. B. W. Fyhn,et. al. (2009), Geological development of the Central and South Vietnamese margin : Implications for the establishment of the South China Sea , Indochinese escape tectonics and Cenozoic volcanism, Tectonophysics 478

Figure 1.2 Distribution of Faults and Folding on Indochina Block (After M.B.W.Fyhn et.al., 2009)

1.6 Figure 1.3 shows a typical geological cross section from the SW to the NE near Ha Noi (Dan Phuong). It is evident that the surface of the delta plain is entirely covered by thick alluvial and diluvial deposits with a base layer of cobble stone and boulders. Bed rocks in this area are composed of Cambrian bed rocks, such as various schist of lime stone, conglomerate and sand stone, which were overlaid with middle Mesozoic rocks, such as basalt, tuff, sand stone, silt stone, shale etc.

1.7 Near the mouth of the Song Hong River, numerous sand mounds are observed in the area of the Ba Lat Delta plain. Figure 1.4 shows a typical geological cross section of that region. It can be seen that sand mounds (or the barrier-spit) have been formed from the upstream of the delta area to that of the downstream sequentially with naissance mechanism of the sand mounds, which is due to decrease in outflow velocities and lateral expansion of river outflow at the mouth of river.

Neogene, siltstone, claystone and sandstone

SW

A South Channel North Channel Red River

NE

BLK 86

Holocene

Pleistocen

san

cla

clay

Source: F. Larsen,et. al. (2008), Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain,Vietnam, Applied Geochemistry 23

Figure 1.3 Typical Geological Cross Section near Ha Noi (After E.Eiche et.al., 2008)


1-4

1830AD

Ba 1910AD

1980AD

1980AD

2000AD

Late Holocene

Late Holocene

Middle Holocene Early Holocene

Source: D. S. Van Maren (2005), Barrier formation on an actively prograding delta system : The Red River Delta, Vietnam, Marine Geology 224

Figure 1.4 Geological Cross Section of the Ba Lat Delta near Nam Dinh (After D.S. van Maren, 2005)

1.8 In the other southern area surrounding the Kon Tum massif, from Nha Trang to Long Thanh of the HSR route, is known as the Dalat Folding or the Indochina Folding as the present countries of Cambodia, Malaysia and Thailand, as well as Vietnam, are included in the block.

1.9 Strata of the basement of this area is composed of sand stone, silt stone etc., and granite, basalt, rhyolite and other silica type rocks, which erupted from rifts around plateaux boundary during the Tertiary and Quaternary periods. Therefore, several tunnels are planned from Nha Trang to Ca Na. Geology in this area is mainly composed of sedimentary rocks of the Jurassic period and acidic rocks of the Cretaceous period, which formed a basement complex, and acidic intrusive. The basement complex is composed of sandstone, siltstone and rhyolite group (andesite, rhyolite, dacite, etc.) and the intrusive are composed of acidic rocks as granite grope (granite, granodiorite, diorite, etc). Basalt is widely distributed from Local Road TL765 to Long Tanh area and forming the large basalt plateaux.



1-5

1.10 Geology of sedimented plateaux and plains near the coast is composed of Quaternary deposits on base rocks. The composition of strata is similar to that of the Annamitic Folding area, though no significant river has caused thinning of the Quaternary sediments. Massifs and horst of lime stone exist at various locations in this area.

1.11 Along to the cost from Phan Thiet to Phan Ri Cua, large sand hills are observed, which are mainly composed of sand of marine deposit. This area is called the “East Sea” and consists of a wide and thick deposit of sand layers where eroded materials of the Mekong River have been transported by ocean drift and northeasterly winds.

1.12 The adjacent southern area of the Dalat Folding, in the HSR route of Long Thanh to HCM, is the extensive Mekong Delta, covering an extensive lowland area of over 40,500km2 with an average elevation of +2m above sea level. The Mekong River in Vietnam flows from the NW to the SE, whose direction coincides with that of the Mae Ping Shear zone (see Figure 1.2).

1.13 Figure 1.5 shows an example of a geological section of Dalat Strungtrng. Sand and fine materials, transferred and deposited by the Mekong River during the “Transgression” stage, form a thick soft soil sediment, which was deeply eroded due to glacial activity during the Holocene epoch.

1.14 Close to the river mouth, a decrease of flow causes reduction of fluvial transport capacity of eroded sand, silt and clay. Thus, sedimented sandy hills are present and lagoon systems are composed in front of the river mouth. Consequently, growth of the costal territory is observed (from 60 to 80 meters per near Ca Mau Cape). It is a typical strata condition that the thickness of these sandy barrier-type deposits is approximately 10 m, resting on a 40 to 50 m thick silt and clay layer of the Holocene.

Source: T. K. O. Ta ,et. al. (2002), Holocene delta evolution and sediment discharge of the Mekong River , Southern Vietnam , Quaternary Science Reviews 21

Figure 1.5 Typical Geological Cross Section of Dalat Strungrng (After T.K.O. Ta et.al., 2002 )



2-1 2-1

2 GEOLOGICAL SURVEY FOR NORTH SECTION

2.1 Outline of Soil Structures, Topography and Geology

2.1 Table 2.1.1 shows site survey results of land use, regional topography and geology of each area of the HSR north section, which is divided into seven subsections. In the table, numbers of soil structures, subtotal length and a rate of length of the structures against that of each subsection are shown.

2.2 In the first group of subsections, S-①, ②, ③, ⑤ and ⑦, the HSR route passes

through mainly a plain area, though in the middle part of S-⑦, the route runs through a

mountainous area. In the second subsections, S-④ and ⑥, some tunnels are planned to

be constructed as the route goes through mountainous areas or plateaux. It is also found that in the second group of subsections many embankments are planned to be constructed because of the ground conditions.

2.3 Table 2.1.2 shows an outline of eight tunnels planned in the north section of the new alignment. Composition of rocks at the sites are a kind of sedimented stones such as sandstone, siltstone, conglomerate, limestone etc., that were deposited in the Ordovician, Permian or Triassic period, and then uplifted due to transpressional movement related with the Annamitic Folding. It is considered that they are almost robust and hard rocks for the construction of tunnels as the hardness of the rocks are classified into the C1 class.

2.4 Discussion of regional topography and geology is presented in the following.


2-2

Table 2.1.1 List of Soil Structures, Land use and Comments on Topography & Geology

Tunnel Cut slope Embankment Land useNum/TL/(TL/SL) Num/TL/(TL/SL) Num/TL/(TL/SL)

0 0 6 sites

0 0 11780m

― ― 25.90%

0 0 0

0 0 0

― ― ―

0 0 3 sites

0 0 2016m

― ― 5.60%

4 sites 58 sites 56 sites

6390m 3200m 24404m

12.70% 6.40% 48.50%

0 0 7 sites

0 0 10140m

― ― 37.60%

3 sites 60 sites 77 sites

5,420m 6,260m 36,610m

9.00% 10.40% 60.50%

1 site 6 sites 22 sites

3,590m 400m 26,980m

8.30% 0.90% 62.70%

Subsection soil structures

Nam DinhNinh Binh(103.056)

Phu Ly(43.030)

Nam Dinh(67.339)

No.

22.124

from (kilopost)

③ 35.717

Phu Ly

P-7(Tho

Truong)

Thanh HoaP-6

(153.326)

Ngco Hoi(0.308)

⑥

⑤

②

①

④ Ninh Binh

⑦

P-6(Luat Thon)

P-7(240.780)

43.010

26.984

to (kilopost)

distance(km)

45.523

50.270Thanh Hoa(153.326)

Vinh(283.790)

60.470

Comments on Topography and Geology

●Urban area and suburbs areawith high density of population.●The area is an extensive deltaplain of the Song Hong river andthe Day river, where is madeavailable for agricultural land ofrice etc.

●An extensive delta plain ismade available for agriculturalland of rice etc. ●Channels foragricultural purpose aredeveloped, where as smallnumbers of ponds and cutofflakes are observed. ●An area oflow population density.

●A vast delta plain was formed due to activiy of the Song Hong river andthe Day river, which flow roughly from the NW to the ES direction with agradient of 0.059 m/km. ●Many ponds with various sizes, cutoff lakes ofthe rivers and channels are observed in this area. ●The HSR route in thissubsection goes through a delta plain of +5m to +8m above sea level. ●Geological constitution of strata composes of alluvial clayey layersmeasuring 30 to 35m thick, which covers a diluvial clayey layer ofmeasuring 15 to 25m thick. Underneath this layer, a diluvial gravel layerof several meters thickness is observed. ●The basement rocks arecomposed of siltstone, claystone and sandstone of the Tertiary period.

●This subsection belongs to a southern part of the Ba Lat delta plain of theDay river. ●Ground elevation is above +1m to +2ｍ from the sea level. ●The HSR route goes down almost parallel along the coast line with adistance of 30km to 40km. ●Sensitive alluvial clayey layers measuring30m in thickness in total covers diluvial clayey layers with depth of 20m. ●Thickness of the alluvial clayey layers decreases towards direction of NinhBinh. ●A poorly graded gravel layer with thickness of several meters isobserved near Nam Dinh, whereas no gravel layer, but a limestone bedrock is observed near Ninh Binh. ●Composition of the layers in thissubsection was caused by erosion due to glacial activity.

●This subsection locates in the northern part of the Annamitic Folding, andplateaux and massifs are left with insignificant erosion. So, construction of4 tunnels are planned. 　　●Rocks of the plateaux and massifs arecomposed of sandstone, siltstone, conglomerate, clay shale etc..Classification of these rocks mainly belong to the C1-class . ●At or nearthe T-1 and T-2 area (Tunnel-1 and -2), clear faults are observed, whereasno clear fault can not be found at the area of No. T-3 and T-4 in thegeology map. ●The base layer of the ground near Thanh Hoa iscomposed of stiff clay with over 50 blow counts of the SPT.

●Ninh Binh and Than Hoa haveevolved as major populationareas along river-side city of theDay river and Ma riverrespectively. ●Several lakes are observed,which are utilized for the purposeof agriculture ●Low land areais cultivated for rice paddies.●Channels are developed foragricultural purpose in this area.

●This subsection is composed of a vast delta plain due to the Lam riverand a mountain area which belong to the Annamitic Folding. ●In the HSRroute, construction of T-8 tunnel in a mountain of +300m height is plannedwhich is composed of sandstone, silt stone etc. of the D2-C1 class. ●There is a possibility to be found faults in the area.　 ●In the delta plainarea thick alluvial clayey deposits measuring 30m in thickness is coveringa diluvial thin sand layer, and a gravel layer of the Tertiary formation.

●This area locates at the southern part of the Annamitic Folding, and theHSR route passes through mountains areas of less than +200m heightabove sea level. ●Construction of tunnels at 3 sites are planned in thissubsection, T-5 and 6 pass through mountains of +190m above sea level.Sandstone, siltstone, conglomerate etc. of the C1-class are estimated ascomposition of mountain rocks. ●T-7 passes through amountain of 120ｍ above sea level of limestone, marl etc. of the C1-class .●Construction of banking is planned in this subsection, and the rate for thesubsection distance becomes over 60%. ●Faults are observed at theneighboring areas of the tunnels.

●The delta plain was formed due to deposition of the Song Hong river,which flows from the NW to ES almost along the direction of the ASRRSZ(shear zone). ●Thickness of alluvial clayey layers has atrend of increasing from Phu Ly to Nam Dinh, and thickness of alluvialclayey layers becomes over 60m near Nam Dinh. ●The Ba Lat Deltaplain is formed near the mouth of the Song Hong river (near Nam Dinh),where alluvial, thick, and sensitive soft clayey layers sedimented at theTransgression stage. No diluvial clayey layer is observed near Nam Ding.●In the Ba Lat Delta, numerous sand mounds are observed. ●A baselayer of this subsection is composed of a sedimented gravel with poorlygraded particles.

●Plateaux in this area areavailable for dry field crops, andmountain area is used for treeplanting. ●There aremany lakes, one of the biggestlakes here is the Lake Yen My,which are used for reservoirs ofagricultural purpose, as well asaqua cultivation of fresh waterfishes.

●The area is an extensive deltaplain of the Song Hong and SongDao river, where is madeavailable for agricultural land ofrice etc. ●Channels aredeveloped for agriculturalpurpose. ●In the coast area, fishponds are constructed for use ofaqua cultivation.

●Vinh has evolved as a majorpopulation area near the mouthof the Lam river. ●Delta plainof the river is available for ricepaddies or dry fields of crops.●The mountain area is used fordry fields of crops or planting treeareas. Several lakes and pondsare observed, and mainly usedfor reservoirs of agriculturalpurpose.

●Extensive plane area with less than +10m above sea level was formedas a vast delta plain of the Ma river and the Yen river. ●In southern areafrom Than Hoa, several meters alluvial clayey layers sedimented on thickdiluvial clayey layers because of less erosion of the glacial activity than thethat near Nam Dinh or Ninh Binh. ●A stiff clay layer with over 50 blowcounts of the SPT composed of the base layer in this subsection, which isestimated as a deposit of the Tertiary formation.

●The area is made availablemainly for rice paddies, thoughsome area is used as dry fieldsfor crops. ●Densepopulation area locates along thecost with +8m to 12m above sealevel.




2-3 2-3

Table 2.1.2 Details of Tunnels: The North Section of the HSR Route

From To

1 Tam Diep 110,760 114,390 3,630 63 12

*Upper sub formation :massive limestone,dolomitezed limestone 300-450 m thick*Lower subformation:　limestone,　marl,cherty　limestone,　300-450 m thick*Dong Giao formation:　Uppersubformation light-colored massivelimestone marl.Major fault is crossing at the center partnearly right angle.

Triassic period(T2adg)

C1

2 Ha Trung 124,010 124,810 800 34 0

*Dong Son formation : quartzitic sandstone,siltstone ,calcareous sandstone,360 mthick*Ham Rong formation: sandstone, siltstone,sandy limestone, colithic limestone, cherty.No major fault is written in geology map.

Permian(P3ct)

C1

3 Hoang Khanh 1 134,960 135,280 320 29 ―Ham Rong formation: sandstone, siltstone,sandy limestone, colithic limestone, chertylimestone 500-600 m thick. No major fault.

Cambrian-Ordovician(E3-Q1hr)

C1

4 Hoang Khanh 2 136,510 138,150 1,640 245 16

Dong Son formation : quartzitic sandstone,siltstone ,calcareous sandstone,360 mthick. No major fault is written in geologymap.

Ordovician(O1ds)

C1

5 Thanh Ky 1 188,640 190,490 1,850 154 20

Dong Do formation: Upper subformation:red-colored sandstone ,conglomerate,gritstone ,500-900 m thick. No major fault iswritten in geology map.

Triassic(T3u-rdd2)

C1

6 Thanh Ky 2 191,230 192,670 1,440 171 ―

Dong Do formation: Upper subformation:red-colored sandstone ,conglomerate,gritstone ,500-900 m thick. No major faultis written in geology map.

Triassic(T3u-rdd2)

C1

7 Quynh Vinh 208,730 210,860 2,130 95 12Dong Trau formation: Uppersubformation:limestone,marl.600 m thick .No major fault is written in geology map.

Triassic(T2adt2)

C1

8 North Vinh 261,200 264,790 3,590 294 12

Upper subformation; sandstone, silt stone,intercalated with shale, about 1000m thick.Unconformity of Palepzoic and MesozoicRocks.

Ordovician(O3s1sc3)

D2-C1

TOTAL 15,400

Geo. period(Legend of theG. map) Class

Estimated GeologyNo LocationKilo Post Length

(m)

MaximumOverburde

n (m)

MinimumOverburde

n (m)


1) Site Survey Results on Regional Topography and Geology

(1) Division of Ngoc Hoi–Phu Ly (Nam Dinh)

2.5 Figure 2.1.1 shows a geology map and the new alignment of HSR route from Ngoc Hoi, Phu Ly to Nam Dinh. The route between Ngoc Hoi and Phu Ly runs almost from the norrh to the south along the right bank side of the Song Hong river. Ground elevation of the Ngoc Hoi station is approximately +5m above sea level, and elevation decreases gradually from upstream of the river to the downstream reaches.


2-4

Ha Noi

Ngoc Hoi

Phu Ly

Nam Dinh

26.23Km


Figure 2.1.1 Geology and the HSR Route from Ngoc Hoi to Nam Dinh

2.6 Geological constitution of strata mainly consists of silty clay of alluvial deposits measuring 30 to 35 m in depth near Ngoc Hoi, which covers a clay layer of diluvial deposits with a depth of 15 to 25 m. Underneath this layer, there is a diluvial gravel layer measuring several meters in thickness.

2.7 The composition of the layers, mentioned above, shows that of a typical one in a delta topography or sedimented plain in South-East Asian countries. Their lower layers are composed of a bed rock of the Cambrian period, which was eroded by glacial activity in the Quaternary period.

2.8 Figure 2.1.2 is a picture of an area for the planned Ngoc Hoi station, and Figure 2.1.3 shows a scenery of paddy field in the Song Hong river delta near Phu Ly. It is evident that the area is covered with a swampy, sensitive and very soft clayey layer.

2.9 The northern area of the ASSRSZ (the Aiao Shan-Red River shear zone, see Figure 2.1.2 in the previous section), namely the subsection from Ngoc Hoi to Nam

Dinh (S-① and ②), belongs to the most southern part of the South China plate. As the

tectonic plate here was covered with shallow sea during transgression in the Quaternary period, it is supposed that thickness of the Quaternary deposits increases from Ngoc Hoi to areas approaching Nam Dinh. However, the geological composition of the layer near Nam Dinh completely differs from that of them.



2-5 2-5


Figure 2.1.2 Construction Site of the Ngoc Hoi Station (Ngoc Hoi)


Figure 2.1.3 Vast Rice Field in the Song Hong Delta (Ngoc Hoi–Phu Ly)

(2) Subsection of Phu Ly to Nam Dinh (Ninh Binh)

2.10 The HSR route goes down from Phu Ly to Nam Dinh, passing through an area between the Song Hong River and the SSRSZ from the west to the east. The downstream area of the Song Hong River is referred as the "Ba Lat Delta plain" (see Figure 2.1.1). It is known that the most downstream delta which is 23.5 km from the cost line of the present-day formed in the last 500 years (here, average seaward growth was about 5 km/century).

2.11 In the area near Nam Dinh (to Ninh Binh), which is 32.5 km from the cost line of Gulf of Bac Bo, geological composition is quite different from that from Ngoc Hoi to Phu Ly; It is considered that thickness of the Quaternary sediments increases when approaching Nam Dinh. However, it is known that the geological composition of this section is not similar to that of the subsections of Ngoc Hoi to Phu Ly. That of the areas near Nam Dinh and Ninh Binh differs from those mentioned above. This is because, the bed rocks have been eroded significantly (over 60m in depth) due to glacial activity in the Quaternary period. Then the alluvial deposits were sedimented when the sea covered the area due to transgression. As a result, a deep layer of alluvial deposit, namely very soft and sensitive clayey soil, became sedimented thickly near the costal area of Nam Dinh to Ninh Binh. In the Ba Lat Delta plain area, a decrease of flow velocity causes reduction of the transport capacity of out-flowing effluents, and as a consequence, causes promotion of deposition close to the river mouth. Subsequently, sand mounds appeared in front of the river mouth. Direction of


2-6

flow changed after a sand mound was formed and, subsequently, the naissance mechanism of a sand mound works in succession. It is known that thickness of these sandy barrier deposits is approximately 10 m, resting on a 40 to 50 m thick Holocene silt and clay layer.

2.12 Figure 2.1.4 and Figure 2.1.5 show views of fields in the suburbs of Nam Dinh, a part of which is used for dry fields for crops, rice paddy fields or ponds for aqua cultivation with well developed water channel systems. Figure 2.1.6 shows a view of the Song Day River near Ninh Binh.

rice field pond

dry field


Figure 2.1.4 Land Use in Suburbs of Nam Dinh (Rice Field, Dry Field for Crops and Pond for Aqua Cultivation)


Figure 2.1.5 Extensive Rice Field (Nam Dinh –Ninh Binh)



2-7 2-7


Figure 2.1.6 Song Day river (Ninh Binh)

(3) Subsection of Nam Dinh to Thanh Hoa

2.13 Figure 2.1.7 shows a geology map and the HSR route from Nam Dinh to Thanh Hoa, which goes down from the NNE to the SSW along to the coast-line with distance of ca.16 km inland, and passes through an area of the Annamitic Folding (see Figure 2.1.2).

2.14 Figure 2.1.8 shows a mountain side view near Tunnel-1 (Ninh Binh–Thanh Hoa), in which ranges of odd shaped mountains can be seen. This is because of limestone and marl eroded, are present.

2.15 The outline of geological composition of layers in the plain area from Nam Dinh to Ninh Binh is similar to that observed at Nam Dinh. Over 50 to 60 m of the thick alluvial deposit covers bed rock. This topography is a result of the bed rocks having been eroded deeply (over 60 m in depth) due to glacial activity and transgression in the Holocene. For these sensitive and soft clayey layers in this region attention must be paid careful for design and construction of soil structures for the HSR.

2.16 In the southern area from Ninh Binh, plateaux and massifs are less than 1000m high. These were formed during the Hercynian orogenetic movements and have been left with relatively minor erosion in this area. Here, four tunnels are required to be constructed. Plateaux and massifs are mainly composed of limestone, alternate layers of sand-stone, silt-stone and shale, conglomerate, intrusive basalt, gneiss etc. (see Table 2.1.2). Several faults and folding are observed here.

2.17 In the plain area near Thanh Hoa to Point-6 (Luat Thon) the outline of geological composition of layers is similar to those observed from Phu Ly to Nam Dinh, though the alluvial deposit sediment is much thinner than that as there is no large river there.

2.18 Figuren 2.1.9 shows a view of the Song Ma River, along which Thanh Hoa City is located.


2-8


Figure 2.1.7 Geology and the HSR Route Nam Dinh to Thanh Hoa


Figure 2.1.8 Limestone Mountains near Location of Tunnel-1 (Ninh Binh–Thanh Hoa)



2-9 2-9

Figure 2.1.9 Scenery of the Song Ma River (Thanh Hoa)


(4) Thanh Hoa to Vinh

2.19 Figure 2.1.10 and Figure 2.1.11 show surfacical geology map and the alliament of the HSR route between Thanh Hoa to Point-7(Tho Truong), and Point-7 to Vinh respectively.

2.20 In the area of P-6 (Luat Thon) to P-7 (Tho Truong), plateaux and massifs, formed during the Hercynian orogenetic movements, remain with insignificant erosion in this section. Three tunnels are planned to be constructed in this area. The area is mainly composed of thick red-colored sandstone, conglomerate, grit stone, limestone and marl. Several faults and folding are observed there (see Table 2.1.2). Figure 2.1.12 shows a mountain area for Tunnel 5 and 6. The area of plateaux is used for some for dry field crops and for rice paddies. Figure 2.1.13 is a view from a location near Truong Lam, in which a mountain range of limestone is observed.

2.21 The region of Poin-7(Tho Truong) to Vinh is composed of two plain areas, the northern area and the southern area, surounding the mountain area in the middle; Geological composition of the former plain is similar to that at Thanh Hoa (Br-9) due to the similarity of topograpy, as there is no large river in the area. Whereas, that of the latter is similar to that at Nam Dinh (Br-4). It is assumed that the bed rocks have been eroded deeply (less than 30 m in depth) due to glacial activity of the Lam river in the Quaternary period, then the alluvial deposits were sedimented when the sea covered the area during transgression in the Holocene epoch.

2.22 Figure 2.1.14 shows a view at the Depo area near Vinh station. Rice paddies cover vast areas of the delta plain of the Song Lam River.

2.23 In the middle area of P-7 to Vinh, a tunnel is planned through a 230 m high mountain near the southern boundary of the Annamitic Folding. Geology of the area is composed of sandstone, silt stone and intercalcated with shale formed in the Ordovician period. Possibility of existing faults in the mountain is considered as geological formation adjacent to the N-S boundary changes into sandstone, siltstone, congromerate, shale etc. formed in the Triassic period.


2-10

2.24 Figure 2.1.15 shows a view of a mountain of Tunnel-8. In the picture, the geological condition of a cut slope of the mountain, which area was redeposited after a slope failure, can be observed.


Figure 2.1.10 Geology and the HSR Route from Thanh Hoa to P-7 (Tho Truong)



2-11 2-11


Figure 2.1.11 Geology and the HSR Route from P-7 (Tho Truong) to Vinh


Figure 2.1.12 Mountains of Tunnel-5 & 6 and Typical Land Use (P-6–P-7)


2-12


Figure 2.1.13 Limestone Mountains near Truong Lam (P-6–P-7)


Figure 2.1.14 Construction Site of the Depo for the HSR (Vinh)


Figure 2.1.15 Mountain for Tunnel-8 and Geology of a Cut Slope (P-7–Vinh)



2-13 2-13

2.2 Boring Investigation

1) Introduction

2.25 Based on the Agreement signed on June, 07th, 2012 between Transport Investment and Construction Consultant Joint stock Company (TRICC, JSC) and Japan International Cooperation Agency Study Team (JICA Study Team) for Geological investigation for Ha Noi–Vinh Section.

2.26 The Terms of Reference (TOR) of soil investigation prepared by Japan International Cooperation Agency (JICA); Table 2.2.1 shows field tests and laboratory tests, which were carried out. In the table, regulations used for soil tests and total numbers of soil tests are also given.

Table 2.2.1 Variation of the Field Investigation and the Regulations Used

Field work: regulation unit total

Drilling : 22TCN259-2000 meter 385.26 Sampling : ASTM D1587 sample

Standard penetration test : JIS A 1219-2001 test 243Laboratory testing :

Grain size analysis : JIS A 1202-1999 sample 113 Moisture content : JIS A 1476-2006 sample 113 Specific gravity : JIS A 1476-2006 sample 113 Atterberg limits : JIS A 1205-1999 sample 113 Consolidation test : JIS A 1217-2000 sample 24 Triaxial compression test type (UU) : ASTM D2850-90 sample 24 Triaxial compression test type (CU) : ASTM D4767-90 sample 4 Direct shear test : ASTM D3080 sample 4 Soil classification : ASTM D2487-93 sample 113

Source: JICA Study Team. Designations; Japan Industrial Standard, Vietnamese standard and ASTM

2) Procedures for Field Works

(1) Drilling

2.27 Drilling work was carried out from June, 08th, 2012 to June, 26st, 2012. Table 2.2.2 shows coordinates of the field test locations with a map. In the table, details of the field tests, such as recorded depth of the borehole tests, SPT numbers and name of the closest city are listed. The main objective of this soil investigation was to obtain soil properties of clay layers, which are used in estimation of consolidation behavior due to embankment, and to find a bearing stratum and depth for viaduct foundations (condition is a 5m layer with over 50 N-value of the SPT).

2.28 The actual work quantities are as follows: The drilling machine is XY-1 (made in China). Method of drilling is rotary with bentonite. The hole was commenced by driving steel casing of 127mm diameter. Figure 2.2.2 to Figure 2.2.8 show pictures of the drilling work at the each site and Figure 2.2.9 shows samples in steel casing, as an example, which were obtained by the sampling works.


2-14

Table 2.2.2 Location, Depth of the Borehole Tests and Number of the SPT

N E

385.26 243

19o39'36.62"

18o 54'44.52"

18o 37'52.07"

105o 52'8.87"

106o 08'1.60"

105o'58'8.15"

105o 49'58.58"

105o 43'30.12"

105o 36'51.95"

105o 38'29.53"

Notes No Name of borehole

Depth (m)Num. of

SPT

Coordinates

Nam Dinh Province(Nam Dinh)

1 Br.1 67.54 37Ha Noi City(Nogc Hoi)

2 Br.4 76.65 50

20o 48'45.43"

20o '25'7.45"

Thanh Hoa Province(Nghua Trang)

3 Br.6 51.42 34 Ninh Binh Province(Ninh Binh)

4 Br.8 50.33 31

20o 11'33.16"

19o 51'29.64"

Vinh Province(Vinh)

Total

5 Br.9 59.42 40

7 Br.13 36.45 23

Thanh Hoa Province(Thanh Hoa)

6 Br.12 43.45 28Vinh Province(Dien Trung)



Figure 2.2.1 Locations of Boreholes were Selected by JICA’s Engineer and TRICC’s Engineer Determined in the Field



2-15 2-15

Figure 2.2.2 Drilling of Br.1







Figure 2.2.9 Samples in Stainless Steel Casings ( Br-4)



2-16

(2) Sampling

2.29 A thin wall stainless steel tube, shown in Figure 2.2.10, was used for taking undisturbed sample. Dimension of sampling tube is as follows:

(i) Length: 650 mm

(ii) Thickness: 2 mm

(iii) Inner diameter: 72.4 mm

(iv) Outer diameter:76.4 mm

2.30 The area ratio A of thin wall tube = [(76.4)2 – (72.4)2]/ (72.4)2 = 10.2 % < 20%


Figure 2.2.10 Thin Wall Tube Sampler Used

2.31 In cohesive soil, undisturbed sample (UD) was taken by pressing (in soft soil) or hammering (in stiff soil) thin wall stainless steel tube sampler to the bottom of the borehole after cleaning. After taken, undisturbed sample was sealed with paraffin immediately, labeled, stored in cool place and preserved natural moisture content.

2.32 Disturbed samples had been taken by the SPT split spoon sampler for cohesionless soil and it was placed in plastic bags. All of samples were transported to Geotechnical lab of TRICC in minimum delay for keeping and testing.

(3) Standard Penetration Test (SPT)

2.33 In cohesive soil, after taking undisturbed sample or in granular soil, after drilling to specified depth, standard penetration test (SPT) was carried out according to JIS A 1219-2001 with a hammer of 63.5 kg weight was freely dropped from 75 cm high. The test had been done in both granular and cohesive soil at 1.5 m intervals. SPT was hammered to penetrate into soil 45cm. The number of blows for every 15cm was recorded. The N value is the actual blow of last 30 cm. The SPT test result is shown on boring logs (Figure 2.2.13 to Figure 2.2.19).

3) Laboratory Testing

2.34 The soil samples were tested in the laboratory of Transport Investment and Construction Consultant Joint stock Company (TRICC., JSC) to determine the following properties (see Table 2.2.3):

2.35 ①Particle size analysis P (%), ②Moisture content W (%), ③Wet unit weight w

(g/cm3), ④Specific gravity (), ⑤Atterberg limits LL (%) and PL (%), ⑥Coefficient of

consolidation, ⑦Angle of internal friction and cohesion, ⑧Organic contents.



2-17 2-17

Table 2.2.3 Total Quantity of Investigation

No. Description Unit Quantity

1 Drilling (2 boreholes) meter 385.26 2 SPT Test Test 243 3 Soil Testing Soil Properties Sample 113 Consolidation Test Sample 24 Triaxial Type UU Sample 24 Triaxial Type CU Sample 04 Triaxial Type CD Sample 04


4) Topography, Geomorphology and Geological Structures

2.36 Because the studied alignment is stretched along the northern provinces (Ha Noi, Ha Nam, Nam Dinh, and Ninh Binh provinces) and North Central (Thanh Hoa, Nghe An provinces), it passes through several different terrain geomorphology types. Topography and geomorphology along the line belong to the two (02) primarily geomorphic terrain as follows:

2.37 It is a large area located around the Red River downstream area of northern Vietnam, the region includes three provinces and cities such as Hanoi, Ha Nam, Nam Dinh. Almost the same with the Red River Delta is the central meso-relief.

(1) The Area of Ha Noi Province

2.38 The topography of Hanoi is lower from the north down to the south and from the west to the east with an average elevation of 5 to 20 meters above sea level. According to the alluvial, three quarters of the total natural area of Hanoi is plain, located in the right bank of the Da River, two tributaries of the Red River and other rivers. The mountainous area distribute in the Soc Son, Ba Vi, Quoc Oai, My Duc, with the peak in Ba Vi is 1281 m high, the Gia De is 707 m, Chan Chim is 462 m, Thanh Lanh is 427 m, Thien Tru is 378 m...Within the inner city, there are some low hills such as Dong Da, Nung mountains.

2.39 Hanoi is a city with many lakes, remnants of ancient rivers. Within the inner city, West Lake is the largest lake of about 500 ha. The other lake remains are with medium to small area such as Hoan Kiem Lake, Truc Bach, Thien Quang, Thu Le ... In addition, many large lakes located inside the territory of Hanoi such as Kim Lien, Linh Dam, Ngai Son - Dong Mo, Suoi Hai, Meo Gu, Xuan Khanh, Tuy Lai, Quan Son.

(2) The Area of Ha Nam Province

2.40 It is a province located in the Red River Delta of Vietnam. Abutting to the north is Hanoi, adjacent to the east are provinces of Hung Yen and Thai Binh, and to the south is Ninh Binh province, and to the west-east is Hoa Binh province. The topography is lower from west to east. The west of the province (mainly in Kim Bang district) has hilly terrain. The east is the plain with many low lands.


2-18

Notation:

Thai Binh formation, main component is of sand, dust, clay mixed with botanical residue, brown grey color

Ha Noi formation, main component is of sand, pebble, gravel, and sand mixed with clay dust. The depth varies from 3 - over 40m

Hai Hung formation, main component is of dust, clay, peat coal mixed with organic botanical residue, brown grey color, and black grey color. The depth varies from 2-32m

Le Chi formation, main component is of sand, pebble, gravel, and clay dust contained botanical residue. The depth varies from 7 - over 20m

Vinh Phuc formation, main component is of sand, gravel, dust, clay. The depth varies from 2-32m

Vinh Bao formation, main component is of cemented gravel, cemented pebble mixed with clay sandy

Vien Nam formation, main component is of Ryolit, porphyry, tuff basalt

Na Khuat formation, main component is of calcareous sandstone, dust-stone, clay schist

Source: Geological and Mineral Resources Map of Vietnam

Figure 2.2.11 Geological Longitudinal Section in the Ha Noi Area (After Geology Map of VN)

(3) The Area of Nam Dinh Province

2.41 The topography of Nam Dinh province is divided into two types of terrain, including: Low lands delta region: comprises of the districts of Vu Ban, Y Yen, My Loc, Nam Truc, Truc Ninh, Xuan Truong and it is cleaved by the ponds, lakes, inland canals.

2.42 Coastal plain region: comprises of the districts of Giao Thuy, Hai Hau and Nghia Hung; with 72 km coastline.

(4) The Area of Ninh Binh Province

2.43 It is the province in southern gate of the north, northern Delta region of Vietnam. Despite the existence in the northern delta area, there are only 2 coastal districts of Yen Khanh and Kim Son Ninh Binh which are not mountainous. Ninh Binh is adjacent to Hoa Binh, Ha Nam to the north, Nam Dinh province to the east over the Day River, Thanh Hoa province to the west, the sea (Gulf of Tonkin) in the southeast.

2.44 In this position the bottom end points of the triangle the Red River Delta, Ninh Binh includes the three types of terrain. The hilly and semi-mountain-plain distribute in the Northwest including Nho Quan, Gia Vien, Hoa Lu, Tam Diep districts. Coastal plains distributes in the southeast of the two Yen Khanh and Kim Son districts. Alternating between two large areas is the area hollowed transition. Ninh Binh has a

T2nk1 T1vn

N2vb Q13vp

Q11lc Q2

1-2hh

Q12-3hn Q2

3tb



2-19 2-19

coastline of 18km. Ninh Binh coastline spreads over 100m toward the sea due to alluvial accumulation annually.

2.45 The main components of the geologic structure are mainly River deposits, Marine deposits and River- marine deposits. A summary of the geological conditions that need to be considered in the construction of the HSR line are as follows:

(a) ① The Distributed Areas of River Deposits

2.46 Distributed along the river network in the North Delta. The main components of deposit are clay, sandy clay, clay sand and sand. The water level of the groundwater is often shallow and this kind of water is carbonic aggressive water.

2.47 Processes and the common phenomenon of building dynamic geology are underground erosion, running sand, water flow into the pit works and erosion at the edge of river and accumulation at the river-bed. Earthquakes can occur at the grade of 6 - 7. This area is suitable for civil constructions, industry and transport constructions.

(b) ② The Distributed Areas of Marine Deposit

2.48 Distributed on the wide area at the center and the west side of the delta. The main components are clay, clay mud, sandy clay mud, clay sand mud. The water level of the groundwater is often shallow and this kind of water is carbonic corrosive water.

2.49 Processes and the common phenomenon of building dynamic geology are underground erosion, running sand, water flow into the pit works and marsh in some places. Earthquake can occur at the grade of 5 - 6. This area contains the layer of weak soil which is quite thick at the surface and varies in complexly so there is potential for irregular settlement. Attention needs to be paid to the phenomena of underground erosion, running sand river mouth. Construction in these areas is likely to face difficulties.

2.50 In areas of Ninh Binh province, the route with the line passing through the limestone mountains. Limestone karst cave is developed so as to survey and design should pay attention to this problem.

2.51 In general, the North Delta was founded by many varied deposits, especially formed by the weak soil with a high thick layer that varies in complexity so it is necessary to design and build constructions carefully and need for special methods designing and constructing foundations in some section in this area.

5) Topography and Geomorphology of the Coastal Plaing from Thanh Hoa to Nghe An

2.52 North-central strip of land is surrounded by mountains that run along the west slopes of the east coast. Particularly in mountainous western Thanh Hoa province has an elevation from 1000 - 1500m. Mountainous area of Nghe An which is the beginning point of the Truong Son mountain is very rugged terrain, much of the high mountain locates here. Thanh Hoa plain which formed by alluvium material from the rivers of Ma and Chu, accounts for nearly half the area and it is the widest plains of Central Vietnam.


2-20

(1) The Area of Thanh Hoa Province

2.53 Thanh Hoa terrain is lower from the Northwest down to Southeast. In the northwest, the mountains which are higher than 1,000 m to 1,500 m sloping, extend and expand to the southeast. Based on the terrain, Thanh Hoa can be divided into regions as follows:

2.54 Mountainous and highland: mountainous and hilly highland areas accounts for most of Thanh Hoa. Highland hills occupiy a small area and it is fragmented, discontinuous, not as clear as in the North. Mountainous area, accounting for two thirds of Thanh Hoa area, is divided into 3 different parts, including 11 districts: Nhu Xuan, Nhu Thanh, Thuong Xuan, Lang Chanh, Ba Thuoc, Quan Hoa, Quan Son, Muong Lat, Ngoc Lac, Cam Thuy and Thach Thanh. The southern mountain area is low mountains, with the lowest point compared to sea level is 1 m.

2.55 The coastal area: Districts of Nga Son, Hau Loc, Hoang Hoa, Sam Son, Quang Xuong to Tinh Gia run along the coast of Nga Son swamp and estuaries of Hoat, Ma, Yen and Bang rivers. Coastline is long and relatively flat.

(2) The Area of Nghe An Province

2.56 The province has the largest area of North Central Vietnam. Adjacent to the north is the province of Thanh Hoa, adjacent to the south is Ha Tinh province, adjacent to the west is Laos, adjacent to the east is the East Sea.

2.57 Nghe An Province is full of high mountain terrain, highland, plains and coastal areas. The west is the North Truong Son mountain range. It has 10 mountainous districts, of which 5 districts are high mountainous districts. The mountainous districts constitute the western Nghe An. The districts remaining districts are highland and coastal areas, including Quynh Luu, Dien Chau, Nghi Loc, and Cua Lo are adjacent to the sea.

Notation:

Upper - Holocene (a, am, mv): Clay, powder, sand, powder sand, clay powder, Thickness : 5-25m

Dong Son Formation, main components are Quarzt sand-stone, silt stone, sand limestone

Middle - Holocene (m, am, bm): Main components are: clay, clay powder, powder sand, thickness ranges from 2-32.0m

Ham Rong Formation, main components are sandstone, siltstone, sand limestone, alternate limestone, silica limestone

Bac Son Formation, Main components are limestone, marble, silica limestone, dolomite limestone.

Nam Co Formation, main components are Quartzite altinate with silicate chert

Co Noi Formation, main components are grit-stone, sand-stone, siltstone, argillaceous slate

Yen Duyet Formation, main components are sericite schist, limestone, sandstone, clay limestone, blackstone

Ban Pap Formation, main components are sand limestone, silica limestone, limestone

Nam Pia Formation, main components are clay limestone, schist, siltstone.

Source: Geological and Mineral Resources Map of Vietnam

Figure 2.2.12 Geological Section in Thanh Hoa Region

D1np D2pb

P2 yd T1 cn

PR3-1 ncC-P bs

X3-O1 hrQIV2

O1 ®s QIV3



2-21 2-21

(3) The Low Mountain Area - Corrosive Blocks

2.58 Formed by types of rock from different origins. The hardest rock is less exposed and the crust of weathering is thick. Groundwater exists mainly in cracking zones, and the water level of groundwater is deep. Water is carbonic aggressive water with a washing corrosive property.

2.59 Processes and the common phenomenon of building dynamic geology mainly developed the laterization, rock and soil movement on the slope side, surface washout, gully erosion, aggressive and accumulation on the river-bed, and underground erosion. Earthquake can occur at the grade of 7. This region is quite favorable for construction. However, the designer and constructor will need to pay attention to processes and the common phenomenon of building dynamic geology in the design and construction of the civil works.

(4) Aggressive - Accumulation Littoral Plain Alternating Lost Mountain

2.60 Distributed mainly at the north-west side of Thanh Hoa Plain. The components are sandy clay, clay sand, clay mud, sand- pebbly- grit, and in some places, rock exposes under the shape of lost mountain. The water level of the groundwater is often shallow and the water is pressurized. The water is carbonic aggressive water with a washing corrosive property.

2.61 Processes and the common phenomenon of building dynamic geology promulgate commonly cauterization, surface washout and underground erosion. For this aggressive - accumulation littoral plain alternating lost mountain, the building constructions is quite favorable, foundation of constructions can be laid on the natural sub grade, and design for such civil structures in this area is less complex.

(5) Plain Deposit Area with Littoral Dune - Shaped

2.62 It is distributed at Thanh Hoa littoral plain. Its components are sandy clay, clay sand, clay mud, and sand- pebbly- grit. The water level of the groundwater is often shallow. Groundwater often is not corrosive.

2.63 Processes and the common phenomenon of building dynamic geology are building deformation by irregular settlement and running sand. Aggressive and accumulation is not significant.

2.64 The formation varies in complexity according to the area and depth, as such there is a need to undertake further geologic surveys in order to determine the appropriate foundation design that can avoid the possibility of settlement during construction. In addition, the designer and constructor must also pay attention to phenomenon of underground erosion and running sand during the construction work.

6) Geological Engineering Conditions

2.65 Table 2.2.4 (1) to Table 2.2.7 (4) shows detail of soil test results for Br-1, 4, 6, 8, 9, 12 and 13. According to the data received from the field works and laboratory tests, the strata of the investigation area can be classified into several layers, which is shown in the first column, the last column and the second column from the last one. An averages of test data for each test are shown in rows of "Average". Main properties of the each layer are discussed in the section 2.4.


2-22

7) Conclusions

(1) The strata along the HSR route vary remarkably. Topography along the HSR route from Ha Noi to Vinh was discussed.

(2) The foundation of viaducts should apply the cast-in-place piles method. The Head of the Pile should base on the bearing Capacity layer with over 50 blow counts of the SPT.

(3) The choice of friction pile foundation for the project should review and audit specific to each selected stratigraphic depth and stratigraphic pile foundation set.

(4) Sensitive, soft clay layer of the alluvial deposit is observed along all route of the HSR. Thickness of the alluvial clayey layers depends on conditions of sedimentation; In the delta plain area of Nam Dinh to Ninh Binh, alluvial clayey layers reach to over 60m to 70m depth, where as the alluvial layers from Ha Noi to Nam Dinh are measuring 30 to 35m depth. In the plain area from Than Hoa to Vinh, the layers are measuring 10m to 20m depth.

2.66 Several characters of clayey soil are discussed in the following sections. The result of soil investigation in this phase is, as well, not enough to evaluate the entire geotechnical engineering condition of project.

Study for the Formulation of H

igh Speed Railw

ay Projects on Hanoi–Vinh and H

o Chi M

inh–Nha Trang Sections

FINAL R

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T Technical R

eport 5 Geological Survey and Preparation of Topographic M

ap

2-23

2-23

Tab

le 2.2.4 (1) Su

mm

ary of S

oil T

esting

; Br-1 an

d B

r-4

wn(%)

Gs(g/cm3)

gt(g/cm3)

g d(g/cm3)

Sr(%)

n(%)

eoWL (%)

Wp(%)

Ip(%)

ILCV

(cm2/sx10-3)

CC CSPc

(kG/cm2)C

(kG/cm2)j

(o)jCU(o)

CCU(kG/cm2)

j'CU(o)

C'CU(kG/cm2)

jUU(o)

CCU(kG/cm2)

k(cm/s)

BOREHOLE Br.1Layer 1-1 (OH/ML/CL/MH): N489 Br.1 1,2-2,0 UD1 72.5 2.66 1.56 0.9 98.59 66.2 1.96 56.60 38.70 17.90 1.888 0.046 6°32' 0.65x10-3 OH

Blackish grey organicCLAY/Blackish grey SILT/ N490 Br.1 2,7-3,5 UD2 75.6 2.64 1.55 0.88 99.79 66.7 2.00 57.90 39.40 18.50 1.957 0.522 0.772 0.154 0.5 0.038 6°16' 0°25' 0.073 0.59x10-3 OHBrownish grey leanCLAY/Brownish grey elastic N490A Br.1 5,7-6,5 UD4 55.3 2.69 1.68 1.08 99.77 59.9 1.49 45.30 27.60 17.70 1.565 0.057 7°18' 1.01x10-4 ML

N491 Br.1 7,2-8,0 UD5 90.8 2.65 1.42 0.74 93.23 72.1 2.58 67.40 48.30 19.10 2.225 0.046 6°32' 13°27' 0.101 24°56' 0.085 1°07' 0.168 0.66x10-3 OHN492 Br.1 10,2-11,0 UD7 42.1 2.68 1.67 1.18 88.77 56.0 1.27 40.50 23.40 17.10 1.094 3.701 0.296 0.047 0.7 0.080 9°37' 1.4x10-6 CLN493 Br.1 13,0-13,8 UD9 60.2 2.69 1.51 0.94 86.97 65.1 1.86 44.60 36.70 7.90 2.975 0.046 5°14' 1.82x10-6 MH

Average A 66.1 2.67 1.57 0.95 97.50 64.0 1.81 53.50 35.70 17.80 1.710 0.050 6o56'Layer 1-2 (SM-SC): N493A BR 1 15,3-15,75 D1 2.67 25.30 18.50 6.80 SM-SCBrownish grey SITLY CLAYEYSAND Average A 2.67 25.30 18.50 6.80Layer 1-3 (MH/ML/CL): N494 Br.1 17,0-17,8 UD10 65.3 2.67 1.54 0.93 93.19 65.2 1.87 43.10 33.10 10.00 3.220 0.482 0.587 0.136 0.85 0.063 7°49' 1°15' 0.288 1.6x10-6 MHBrownish grey elasticSILT/Brownish grey SILT/ N494A Br.1 19,0-19,8 UD11 37.5 2.66 1.72 1.25 88.43 53.0 1.13 40.30 26.30 14.00 0.800 0.126 13°53' 1.61x10-6 MLBrownish grey lean CLAY N495 Br.1 21,2-22,0 UD12 49.1 2.7 1.68 1.13 95.44 58.1 1.39 43.60 29.70 13.90 1.396 0.080 8°36' 16°25' 0.12 27°03' 0.088 1.45x10-6 ML

N496 Br.1 23,5-24,3 UD13 40.5 2.67 1.71 1.22 90.95 54.3 1.19 44.20 24.70 19.50 0.810 0.115 12°9' 1.04x10-6 CLN497 Br.1 25,6-26,4 UD14 28.4 2.68 1.9 1.48 93.85 44.8 0.81 38.20 20.50 17.70 0.446 0.710 0.141 0.039 0.75 0.115 13°53' 3°33' 0.403 0.54x10-6 CL

Average A 44.2 2.68 1.71 1.19 94.60 56.0 1.25 43.50 26.90 16.60 1.040 0.100 11o13'Layer 1-4 (SP): N497A Br.1 29,7-30,15 D3 1.79x10-2 SPGreenish grey POORLY -GRADED SAND N497B Br.1 33,5-33,95 D5 0.46x10-2 SP

N497C Br.1 37,3-37,75 D7 1.6x10-2 SPN497D Br.1 41,0-41,45 D9 1.77x10-2 SPN497E Br.1 44,9-45,35 D11 0.9x10-2 SP

Average ALayer 1-5 (CL): N503 Br.1 46,9-47,7 UD15 27.5 2.66 1.94 1.52 97.53 42.9 0.75 39.70 21.30 18.40 0.337 0.252 18°15' 0.34x10-6 CLBrownish grey lean CLAY N503A Br.1 49.0-49.8 UD16 32.8 2.68 1.87 1.41 97.56 47.4 0.90 45.10 26.10 19.00 0.353 0.206 16°42' 0.19x10-6 CL

Average A 30.2 2.67 1.91 1.47 98.80 45.0 0.82 42.40 23.70 18.70 0.350 0.100 11o13'Layer 1-6 (SP): N504 Br.1 53,6-54,05 D13 1.44x10-2 SPBlackish grey POORLY -GRADED SAND N505 Br.1 57,4-57,85 D15 0.32x10-2 SP

N506 Br.1 60,4-60,85 D17 0.65x10-2 SP Average A

BOREHOLE Br.4Layer 4-2 (MH/SC): N333 Br.4 UD1 1,4-2,0 65.1 2.61 1.56 0.94 95.62 64.0 1.78 63.50 37.70 25.80 1.062 0.034 6°44' 0.75x10-6 MHBrownish grey Elasticsilt/Brownish grey CLAYEY N334 Br.4 UD2 2,9-3,5 65.8 2.6 1.55 0.93 95.26 64.2 1.80 61.60 36.90 24.70 1.170 0.743 0.526 0.131 0.6 0.034 6°13' 1°24' 0.118 0.54x10-6 MH

N335 Br.4 UD3 4,4-5,0 23.5 2.68 1.97 1.6 93.30 40.3 0.68 26.40 15.40 11.00 0.736 0.092 13°53' 1.77x10-6 SC Average A 65.5 2.61 1.56 0.94 96.20 64.0 1.78 62.60 37.30 25.30 1.110 0.050 9o1'

Layer 4-3 (SM-SC/SC): N158 Br.4 D1 6.5-6.95 2.66 21.50 14.90 6.60 0.51x10-2 SM-SCBrownish grey Silty, CLAYEYSAND/Brownish grey CLAYEY N159 Br.4 D2 8.0-8.45 2.67 22.00 13.70 8.30 0.57x10-2 SC

N160 Br.4 D3 9.5-9.95 2.64 21.80 14.20 7.60 0.59x10-2 SCN161 Br.4 D4 11,0-11,45 2.66 23.30 16.10 7.20 0.32x10-2 SC

Average A 2.66 22.20 14.70 7.40Layer 4-4 (CL/MH): N336 Br.4 UD5 14,9-15,5 40.5 2.68 1.75 1.25 94.88 53.4 1.14 47.20 25.00 22.20 0.698 5.651 0.177 0.047 0.85 0.057 7°49' 0°39' 0.15 1.1x10-2 CLBrownish grey Leanclay/Brownish grey Elastic SILT N337 Br.4 UD7 17,9-18,5 37.4 2.67 1.77 1.29 93.33 51.7 1.07 43.60 23.10 20.50 0.698 0.064 8°17' 1.1x10-2 CL

N338 Br.4 UD10 22,4-23,0 50.7 2.66 1.67 1.11 96.61 58.3 1.40 46.20 24.00 22.20 1.203 0.031 9°34' 1.05x10-2 CLN339 Br.4 UD12 25,4-26,0 55.5 2.63 1.62 1.04 95.46 60.5 1.53 47.60 25.60 22.00 1.359 1.817 0.375 0.091 0.75 0.035 9°28' 0°14' 0.276 0.56x10-6 CLN340 Br.4 UD13 28,4-29,0 38.8 2.65 1.8 1.3 99.06 50.9 1.04 45.50 23.20 22.30 0.700 0.069 11°54' 0.12x10-6 CLN341 Br.4 UD16 32,9-33,5 56.1 2.62 1.61 1.03 95.20 60.7 1.54 48.00 26.00 22.00 1.368 0.056 9°31' 1.16x10-3 CLN342 Br.4 UD19 37,4-38,0 46.4 2.66 1.69 1.15 94.00 56.8 1.31 52.30 32.10 20.20 0.708 0.074 10°8' 1.16x10-6 MH

Average A 46.5 2.65 1.7 1.16 96.00 56.0 1.28 47.20 25.60 21.60 0.970 0.060 9o31'Layer 4-5 (SC): N343 Br.4 UD21 40,4-41,0 26.2 2.7 1.85 1.47 84.52 45.6 0.84 28.10 20.50 7.60 0.750 0.160 14°53' 0.91x10-3 SCBrownish grey CLAYEY SAND N344 Br.4 UD23 43,4-44,0 21.3 2.69 1.92 1.58 81.50 41.3 0.70 26.70 17.40 9.30 0.419 2.722 0.078 0.021 1.1 0.137 16°20' 1°18' 1.08 0.72x10-3 SC

N345 Br.4 UD25 46,4-47,0 24.7 2.69 1.87 1.5 83.79 44.2 0.79 30.30 20.20 10.10 0.446 0.172 18°15' 0.72x10-3 SC Average A 24.1 2.69 1.88 1.51 83.00 44.0 0.78 28.40 19.40 26.50 0.840 0.160 16o29'

Layer 4-6 (CH): N346 Br.4 UD27 49,4-50,0 48.3 2.68 1.69 1.14 95.81 57.5 1.35 53.60 26.10 27.50 0.807 0.092 7°34' 1.47x10-7 CHBrownish grey, Brownish redFat CLAY N347 Br.4 UD29 52,4-53,0 32.9 2.7 1.82 1.37 91.48 49.3 0.97 50.30 23.00 27.30 0.363 0.092 11°54' 0.93x10-7 CH

N348 Br.4 UD31 55,4-56,0 33 2.71 1.84 1.38 92.77 49.1 0.96 52.00 22.50 29.50 0.356 5.135 0.164 0.051 1 0.113 13°3' 0°32' 0.856 0.93x10-7 CH Average A 38.1 2.7 1.78 1.29 94.10 52.0 1.09 52.00 23.90 28.10 0.510 0.100 10o53'

Layer 4-7 (CL): N349 Br.4 UD34 59,9-60,5 30.9 2.66 1.8 1.38 88.57 48.1 0.93 39.70 20.80 18.90 0.534 0.073 7°28' 1.16x10-6 CLBrownish grey, Blackish greyLean CLAY N350 Br.4 UD37 64,4-65,0 34 2.67 1.71 1.28 83.59 52.1 1.09 42.50 21.60 20.90 0.593 0.069 8°20' 1.16x10-6 CL

N351 Br.4 UD39 67,4-68,0 41.7 2.69 1.72 1.21 91.72 55.0 1.22 49.90 25.40 24.50 0.665 0.046 7°34' 1.16x10-6 CL Average A 35.5 2.67 1.74 1.28 87.30 52.0 1.09 44.00 22.60 21.40 0.600 0.060 7o45'

Brownish grey Lean clay.


Blackish grey Lean clay.

Brownish grey Clayey sand.

Brownish grey Fat clay.

Brownish red Fat clay.

Brownish grey Fat clay.

Brownish grey Lean clay.Brownish grey Lean clay.Brownish grey Elastic silt.

Brownish grey Clayey sand.Brownish grey Clayey sand.

Brownish grey Clayey sand. C¸



Brownish grey Lean clay.Brownish grey Lean clay.

Brownish grey Elastic silt. §

Brownish grey Clayey sand. ©u.

Brownish grey Silty, clayey sand.



Blackish grey poorly - graded sand.



Brownish grey Elastic silt.

Greenish grey poorly - graded sand.



Brownish grey lean clay.Brownish grey lean clay.

Brownish grey elastic silt.

Brownish grey silt.

Brownish grey silt.Brownish grey lean clay.Brownish grey lean clay.

Blackish grey organic clay.Brownish grey lean clay.Brownish grey elastic silt.

Brownish grey sitly clayey sand.

Blackish grey organic clay.

Blackish grey organic clay.

Groupsymbol

Group name

Blackish grey silt.

Name of layer (1)No.

Borehole

SampleDepth

Type CU

Int.frictionangle

CohesionInt.

frictionangle

CohesionInt. friction

angle

Dry unitweight

Deg. ofsatu-ration

PorosityVoidRatio

SampleName

Moisturecontent

Specificgravity

Wet unitweight

SUMMARY OF SOIL TESTINGRESULTS

Consolidation test

Coeff. ofconsoli.

Compression index

Expansionindex

Yieldstress ofconsoli.

Atterberglimit

Plasticlimit

Plasticity index

Liquidityindex

Cohesion


Cohension Int. frictionangle


Permeability

Type UUSoil classification & comments

TCVN 5747-1993

Source: JIC

A Study Team.


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

2-24

Tab

le 2.2.5 (2) Su

mm

ary of S

oil T

esting

; Br-6 an

d B

r-8

wn(%)

Gs(g/cm3)

gt(g/cm3)

g d(g/cm3)

Sr(%)

n(%)

eoWL (%)

Wp(%)

Ip(%)

ILCV

(cm2/sx10 3)

CC CSPc

(kG/cm2)C

(kG/cm2)j

(o)jCU(o)

CCU(kG/cm2)

j'CU(o)

C'CU(kG/cm2)

jUU(o)

CCU(kG/cm2)

k(cm/s)

BOREHOLE Br.6Layer 6-2 (ML/MH): N305 Br.6 UD1 1,5-2,1 33.6 2.64 1.79 1.34 91.45 49.2 0.97 38.20 25.30 12.90 0.643 0.097 12°9' 0.81x10-6 MLSilt with SANDY/SANDY elasticsilt N307 Br.6 UD3 4,5-5,1 55.7 2.67 1.67 1.07 99.48 59.9 1.50 55.90 35.80 20.10 0.990 1.161 0.342 0.065 0.6 0.109 7°49' 1°22' 0.14 1.4x10-6 MH

Average A 44.7 2.66 1.73 1.2 97.70 55.0 1.22 47.10 30.60 16.50 0.850 0.100 10o2'Layer 6-3 (CL): N309 Br.6 UD5 7,5-8,1 26.3 2.68 1.94 1.54 95.25 42.5 0.74 28.70 19.70 9.00 0.733 0.097 10°38' 0.58x10-6 CL

Sandy lean CLAYN311 Br.6 UD7 10,5-11,1 27.2 2.69 1.87 1.47 88.15 45.4 0.83 27.50 19.00 8.50 0.965 2.749 0.160 0.036 0.7 0.040 11°8' 1°34' 0.183 1.17x10-6 CL

Average A 26.8 2.69 1.91 1.51 92.30 44.0 0.78 28.10 19.40 8.70 0.850 0.070 10o53'Layer 6-4 (ML/MH): N313 Br.6 UD9 13,5-14,1 54 2.7 1.68 1.09 98.71 59.6 1.48 49.30 28.80 20.50 1.229 0.057 6°1' 1.46x10-7 MLSILT/Elastic SILT N315 Br.6 UD11 16,5-17,1 45.3 2.71 1.68 1.16 91.89 57.2 1.34 47.50 27.50 20.00 0.890 0.074 7°3' 1.31x10-7 ML

N317 Br.6 UD13 19,5-20,1 52.1 2.68 1.69 1.11 98.75 58.6 1.41 55.20 29.80 25.40 0.878 0.510 0.403 0.121 0.83 0.086 6°47' 0°36' 0.136 1.47x10-7 MHN319 Br.6 UD15 22,5-23,1 53.1 2.67 1.62 1.06 93.34 60.3 1.52 56.40 31.10 25.30 0.870 0.074 10°38' 1.34x10-7 MH

Average A 51.1 2.69 1.67 1.11 96.60 59.0 1.42 52.10 29.30 22.80 0.960 0.070 7o38'Layer 6-5 (MH): N321 Br.6 UD17 25,5-26,1 52.8 2.64 1.66 1.09 98.03 58.7 1.42 55.70 30.70 25.00 0.884 0.608 0.383 0.142 1.1 0.080 9°37' 0°20' 0.14 1.06x10-7 MHElastic SILT Average A 52.8 2.64 1.66 1.09 98.00 59.0 1.42 55.70 30.70 25.00 0.880 0.080 9o37'Layer 6-6 (CL): N323 Br.6 UD19 28,5-29,1 40.1 2.68 1.79 1.28 98.23 52.2 1.09 46.40 27.10 19.30 0.674 0.223 15°37' 0.92x10-7 CLLean CLAY N325 Br.6 UD21 31,5-32,1 33.1 2.66 1.84 1.38 94.88 48.1 0.93 40.20 23.60 16.60 0.572 0.364 0.157 0.082 1.2 0.218 16°20' 0°30' 0.46 0.55x10-6 CL

Average A 36.6 2.67 1.82 1.33 97.00 50.0 1.01 43.30 25.40 17.90 0.630 0.220 15o58'

Layer 6-7 (CL/GC): N327 Br.6 UD23 34,5-35,1 28.5 2.7 1.95 1.52 99.16 43.7 0.78 41.70 23.30 18.40 0.283 0.286 16°49' 0.7x10-7 CLLean CLAY/Sity, clayed gravelwith SAND N329 Br.6 UD25 37,5-38,1 19.6 2.77 1.91 1.6 74.27 42.2 0.73 28.60 19.10 9.50 0.053 0.275 20°14' 0.82x10-7 CL

N331 Br.6 UD27 40,5-41,1 18.5 2.77 2.03 1.71 82.65 38.3 0.62 26.80 18.20 8.60 0.035 0.206 22°17' 0.77x10-7 GC Average A 22.2 2.75 1.96 1.6 84.90 42.0 0.72 32.40 20.20 12.20 0.160 0.260 19o49'

BOREHOLE Br.8Layer 8-1 (MH): N452 BR 8 1,5-2,1 UD1 71.3 2.65 1.48 0.86 90.80 67.5 2.08 59.60 35.70 23.90 1.490 0.040 6°47' 1,36x10-7 MHBrownish grey elastic SILT N453 BR 8 4,5-5,1 UD3 67.2 2.63 1.54 0.92 95.07 65.0 1.86 53.40 31.70 21.70 1.636 0.492 0.448 0.110 0.35 0.052 5°30' 0°46' 0.091 1,56x10-7 MH

Average A 69.3 2.64 1.51 0.89 93.10 66.0 1.97 56.50 33.70 22.80 1.560 0.050 6o13'Layer 8-2 (CL): N454 BR 8 7,5-8,1 UD5 32.7 2.68 1.89 1.42 98.80 47.0 0.89 43.50 24.10 19.40 0.443 0.286 18°29' 0,59x10-7 CLGreenish grey, Reddish brownlean CLAY N455 BR 8 10,5-11,1 UD7 27.5 2.72 1.97 1.55 99.07 43.0 0.76 45.70 22.30 23.40 0.222 0.240 15°7' 0,51x10-7 CL

N456 Br.8 13,5-14,1 UD9 29.9 2.69 1.93 1.49 99.91 44.6 0.81 45.70 23.80 21.90 0.279 0.252 18°36' 0,67x10-7 CLN457 Br.8 16,5-17,1 UD11 22.5 2.67 2.01 1.64 95.66 38.6 0.63 34.10 18.60 15.50 0.252 0.149 19°12' 0,26x10-6 CL

Average A 28.2 2.69 1.95 1.52 98.50 44.0 0.77 42.30 22.20 20.10 0.300 0.230 17o52'Layer 8-3 (CL): N458 Br.8 21,0-21,6 UD14 22.6 2.69 2.01 1.64 94.99 39.0 0.64 33.50 17.70 15.80 0.310 0.842 0.111 0.043 0.9 0.183 19°26' 1°29' 0.586 0,27x10-6 CL

Greenish grey lean CLAY Average A 22.6 2.69 2.01 1.64 94.99 39.0 0.64 33.50 17.70 15.80 0.310 0.183 19°26'

Layer 8-4 (CL): N459 Br.8 24,0-24,6 UD16 17.7 2.71 2.09 1.78 91.89 34.3 0.52 41.20 21.10 20.10 <0 0.321 18°15' 0,42x10-7 CL

Greenish grey lean CLAY N460 Br.8 27,0-27,6 UD18 26.2 2.7 1.92 1.52 91.16 43.7 0.78 40.30 20.80 19.50 0.277 0.263 17°4' 0,59x10-7 CLN461 Br.8 30,0-30,6 UD20 30.2 2.69 1.84 1.41 89.47 47.6 0.91 45.80 24.50 21.30 0.268 0.275 18°29' 0,64x10-7 CL

Average A 24.7 2.7 1.95 1.56 90.80 42.0 0.74 42.40 22.10 20.30 0.130 0.290 17°57'Layer 8-5 (CL): N462 Br.8 33,0-33,6 UD22 31.5 2.68 1.8 1.37 88.31 48.9 0.96 37.50 19.90 17.60 0.659 0.160 17°47' 0,83x10-6 CLBrownish grey lean CLAY N463 Br.8 36,0-36,6 UD24 35.3 2.71 1.85 1.37 97.81 49.4 0.98 41.30 22.80 18.50 0.676 0.149 13°53' 0,97x10-7 CL

Average A 33.4 2.7 1.83 1.37 92.90 49.0 0.97 39.40 21.40 18.00 0.670 0.150 15°51'Layer 8-6 (CL): N464 Br.8 39,0-39,6 UD26 26.1 2.73 1.95 1.55 93.63 43.2 0.76 41.50 21.20 20.30 0.241 0.240 16°20' 0,62x10-7 CLReddish brown lean CLAY Average A 26.1 2.73 1.95 1.55 93.63 43.2 0.76 41.50 21.20 20.30 0.241 0.240 16°20'

Yellowish grey, sandy lean clay.

SUMMARY OF SOIL TESTINGRESULTS Moisture

contentSpecificgravity

Wet unitweight

Dry unitweight

Deg. ofsatu-ration

Name of layer (2)

PorosityVoidRatio

Atterberglimit

No.Borehol

eSampleDepth

SampleName

Plasticlimit

Plasticity index

Liquidityindex

Consolidation test

Coeff. ofconsol.

Compressionindex

Expansionindex

Yieldstress ofconsoli.

Permeability

CohensionInt. friction

angleInt. friction

angleCohesion

Int.frictionangle

Cohesion

Soil classification & commentsTCVN 5747-1993Int.

frictionangle

Cohesion

Groupsymbol

Group name

Type CU Type UU


Greenish grey, lean clay.Greenish grey, lean clay.

Greenish grey, lean clay.

Brownish yellow, sandy lean clay.

Brownish yellow, silty, clayed gravelwith sand.

Reddish brown lean clay.

Greenish grey lean clay.





Brownish grey lean clay.Brownish grey lean clay.





Brownish red, sandy lean clay.

Brownish red, silt.Greenish grey, silt.Greenish grey, elastic silt .Greenish grey, elastic silt

Greenish grey, elastic silt .

Brownish grey, sandy elastic silt.

Brownish grey, silt with sand.

Source: JICA Study Team

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2-25

2-25

Tab

le 2.2.6 (3) Su

mm

ary of S

oil T

esting

; Br-9 an

d B

r-12

wn(%)

Gs(g/cm3)

gt(g/cm3)

g d(g/cm3)

Sr(%)

n(%)

eoWL (%)

Wp(%)

Ip(%)

ILCV

(cm2/sx10-3)

CC CSPc

(kG/cm2)C

(kG/cm2)j

(o)jCU(o)

CCU(kG/cm2)

j'CU(o)

C'CU(kG/cm2)

jUU(o)

CCU(kG/cm2)

k(cm/s)

BOREHOLE Br.9

Layer 9-2 (MH): N352 Br.9 1,0-1,6 UD1 51.8 2.67 1.61 1.06 91.05 60.3 1.52 55.90 33.40 22.50 0.818 0.097 9°37' 1.28x10-7 MH

Blackish grey, Elastic SILT N353 Br.9 2,5-3,1 UD2 71.6 2.65 1.53 0.89 95.93 66.4 1.98 68.70 44.40 24.30 1.119 0.344 0.646 0.147 0.45 0.040 6°16' 0°10' 0.066 1.47x10-7 MH

Average A 61.7 2.66 1.57 0.97 94.20 64.0 1.74 62.30 38.90 23.40 0.970 0.070 7o57'

Layer 9-3 (CL): N354 Br.9 4,0-4,6 UD3 20.8 2.68 2 1.66 90.79 38.0 0.61 30.20 17.30 12.90 0.271 0.206 18°29' 0.38x10-6 CL

Greenish grey, Lean CLAY Average A 20.8 2.68 2 1.66 90.79 38.0 0.61 30.20 17.30 12.90 0.271 0.206 18o29'

Layer 9-4 (CL): N355 Br.9 7,0-7,6 UD5 30.9 2.66 1.75 1.34 83.45 49.6 0.99 41.50 21.20 20.30 0.478 0.149 12°9' 1x10-7 CLBrownish grey, Yellowish grey, LeanCLAY N356 Br.9 10,6-10,6 UD7 36.7 2.72 1.78 1.3 91.41 52.2 1.09 44.60 23.50 21.10 0.626 0.172 13°53' 0.98x10-7 CL

N357 Br.9 13,0-13,6 UD9 28.9 2.7 1.92 1.49 96.10 44.8 0.81 43.10 22.30 20.80 0.317 0.656 0.115 0.079 1.35 0.332 17°32' 1°01' 0.756 0.66x10-7 CL

N358 Br.9 16,0-16,6 UD11 26.8 2.72 1.96 1.55 96.55 43.0 0.76 40.50 20.90 19.60 0.301 0.298 17°54' 0.69x10-7 CL

N359 Br.9 19,0-19,6 UD13 28.7 2.7 1.9 1.48 94.04 45.2 0.82 44.10 22.80 21.30 0.277 0.361 17°11' 0.61x10-7 CL

Average A 30.4 2.7 1.86 1.43 92.40 47.0 0.89 42.80 22.10 20.70 0.400 0.190 21o15'

Layer 9-5 (CL): N360 Br.9 22,0-22,6 UD15 24.2 2.68 2.01 1.62 99.17 39.5 0.65 38.90 19.70 19.20 0.234 0.338 18°29' 0.63x10-7 CL

Yellowish grey, Lean CLAY N361 Br.9 25,0-25,6 UD17 19.9 2.68 2.04 1.7 92.59 36.6 0.58 37.80 19.10 18.70 0.043 0.412 20°7' 0.41x10-7 CL

Average A 22.1 2.68 2.03 1.66 96.50 38.0 0.61 38.40 19.40 19.00 0.140 0.370 19o19'

Layer 9-6 (CL): N362 Br.9 29,5-30,1 UD20 24.9 2.71 1.95 1.56 91.56 42.4 0.74 40.90 21.20 19.70 0.188 0.252 20°42' 0.31x10-6 CLYellowish grey, Brownish red, LeanCLAY N363 Br.9 32,5-33,1 UD22 25.1 2.69 1.9 1.52 87.69 43.5 0.77 41.80 20.40 21.40 0.220 0.183 18°57' 0.22x10-6 CL

N364 Br.9 35,5-36,1 UD24 27.5 2.71 1.93 1.51 93.74 44.3 0.80 43.10 23.20 19.90 0.216 0.195 20°7' 0.49x10-6 CL

Average A 25.8 2.7 1.93 1.53 91.10 43.0 0.77 41.90 21.60 20.30 0.210 0.210 19o56'

Layer 9-7 (SM/SC):N365 Br.9 40,0-40,45 D1 2.67 19.60 15.30 4.30 - 2.41x10-1 SM-SC

Yellowish grey, SILTY, CLAYED SANDwith GRAVEL. Average A 2.67 19.60 15.30 4.30

Layer 9-8 (SP/SC):N366 Br.9 43,0-43,45 D3 2.65 2.54x10-1 SP-SC

Yellowish grey, Well to poorly gradedSAND with SILT and GRAVEL N367 Br.9 46,0-46,45 D5 2.66 1.89x10-1 SP-SC

Average A 2.66BOREHOLE Br.12

Layer 12-2 (SM-SC): N478A Br.12 2,0-2,45 D1 2.64 19.80 14.10 5.70 0.58x10-2 SM-SCBlackish grey SILTY CLAYEY N478B Br.12 3,5-3,95 D2 2.65 21.50 15.30 6.20 0.4x10-2 SM-SC

Average A 2.65 20.70 14.70 6.00

Layer 12-3 (ML-CL/CL): N479 Br.12 4,4-5,0 UD1 23.4 2.65 1.83 1.48 78.39 44.2 0.79 23.90 17.10 6.80 0.926 0.126 18°15' 0.87x10-3 ML-CLBlackish grey sandy SILTYCLAY/Blackish grey sandy lean CLAY N480 Br.12 5,9-6,5 UD2 42.8 2.64 1.73 1.21 95.59 54.2 1.18 34.20 23.40 10.80 1.796 1.650 0.192 0.029 0.5 0.046 5°14' 0°32' 0.124 1.27x10-3 CL

Average A 33.1 2.65 1.78 1.34 89.70 49.0 0.98 29.10 20.30 8.80 1.450 0.090 11o56'

Layer 12-4 (CL): N481 Br.12 8,9-9,5 UD4 22.5 2.68 2 1.63 93.63 39.2 0.64 33.10 19.40 13.70 0.226 5.321 0.097 0.024 1 0.218 19°12' 1°07' 0.321 0.56x10-6 CLYellowish brown lean CLAY N482 Br.12 10,4-11,0 UD5 38.2 2.69 1.76 1.27 91.91 52.8 1.12 43.70 24.40 19.30 0.715 0.166 15°37' 1.06x10-7 CL

Average A 30.4 2.69 1.88 1.44 94.20 46.0 0.87 38.40 21.90 16.50 0.520 0.220 19o12'

Layer 12-5 (CL): N483 Br.12 13,4-14,0 UD7 30.8 2.72 1.81 1.38 86.28 49.3 0.97 42.90 23.20 19.70 0.386 0.183 17°4' 0.92x10-7 CLYellowish brown, Reddishbrown lean CLAY N484 Br.12 17,9-18,5 UD10 34.2 2.7 1.78 1.33 89.65 50.7 1.03 48.40 25.30 23.10 0.385 3.697 0.119 0.033 1.1 0.183 18°1' 0°54' 0.648 0.67x10-7 CL

N485 Br.12 20,9-21,5 UD12 22.1 2.73 2.01 1.65 92.11 39.6 0.66 39.60 20.20 19.40 0.098 0.424 19°40' 0.62x10-7 CL

N486 Br.12 25,4-26,0 UD15 31.4 2.69 1.84 1.4 91.71 47.9 0.92 42.60 22.70 19.90 0.437 0.240 20°49' 0.69x10-7 CL

N487 Br.12 29,9-30,5 UD18 22.2 2.71 2.02 1.65 93.71 39.1 0.64 40.50 19.80 20.70 0.116 0.447 19°12' 0.12x10-7 CL

N488 Br.12 34,4-35,0 UD21 18.5 2.67 2.11 1.78 98.79 33.3 0.50 35.20 18.10 17.10 0.023 0.218 19°40' 0.4x10-7 CL Average A 29.7 2.71 1.93 1.49 98.30 45.0 0.82 42.80 22.20 20.60 0.360 0.280 19o5'

SampleDepth

SampleName

Wet unitweight

Dry unitweight

Deg. ofsatu-ration

Porosity

Name of layer (3)



No.Borehol

e

Compression index

Expansionindex

Yieldstress ofconsoli


VoidRatio

Atterberglimit

Plasticlimit

Plasticity index Int. friction

angleCohesion

Int. frictionangle

Cohesion

Groupsymbol

Liquidityindex

Consolidation test Type CU

Coeff. ofconsoli.

Type UUPermeability Soil classification & comments

TCVN 5747-1993

Group name

Int. frictionangle

Cohesion

Blackish grey, Elastic silt.

Blackish grey, Elastic silt.

Greenish grey, Lean clay.

Blackish grey silty clayey sand

Blackish grey silty clayey sand .

Blackish grey sandy silty clay.

Yellowish brown lean clay.



Blackish grey sandy lean clay.






Yellowish grey, Lean clay.



Brownish grey, Lean clay.




Yellowish grey, Silty, clayed sandwith gravel.

Yellowish grey, Well to poorlygraded sand with silt and gravel.


Brownish red, Lean clay.


Yellowish grey, Well to poorly graded sandwith silt and gravel.


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2-26

Tab

le 2.2.7 (4) Su

mm

ary of S

oil T

esting

; Br-13

wn(%)

Gs(g/cm3)

gt(g/cm3)

g d(g/cm3)

Sr(%)

n(%)

eoWL (%)

Wp(%)

Ip(%)

ILCV

(cm2/sx10-3)

CC CSPc

(kG/cm2)C

(kG/cm2)j

(o)jCU(o)

CCU(kG/cm2)

j'CU(o)

C'CU(kG/cm2)

jUU(o)

CCU(kG/cm2)

k(cm/s)

BOREHOLE Br.13

Layer 13-2 (ML): N465 Br.13 1,2-2,0 UD1 49.3 2.6 1.64 1.1 93.97 57.7 1.36 41.30 30.40 10.90 1.734 0.040 5°14' 1.14x10-3 MLBlackish grey, Blackish grey siltwith SAND N466 Br.13 2,7-3,5 UD2 49.2 2.65 1.66 1.11 94.00 58.1 1.39 40.20 29.70 10.50 1.857 1.190 0.337 0.071 0.5 0.046 7°49' 0°59' 0.092 1.2x10-3 ML

N467 Br.13 4,2-5,0 UD3 42.6 2.66 1.72 1.21 94.59 54.5 1.20 39.70 26.40 13.30 1.218 0.052 7°3' 1.27x10-3 ML

Average A 47 2.64 1.67 1.14 94.30 57.0 1.32 40.40 28.80 11.60 1.570 0.050 6o44'Layer 13-3 (ML): N468 Br.13 7,2-8,0 UD5 49.6 2.64 1.62 1.08 90.68 59.1 1.44 45.30 31.50 13.80 1.312 0.057 6°16' 13°53' 0.094 26°45' 0.088 1.06x10-3 MLBlackish grey silt with SAND N469 Br.13 10,2-11,0 UD7 44.7 2.67 1.74 1.2 97.43 55.1 1.23 47.50 28.20 19.30 0.855 0.080 7°3' 0.97x10-3 ML

N470 Br.13 11,7-12,5 UD8 47.1 2.62 1.72 1.17 99.60 55.3 1.24 38.30 27.20 11.10 1.793 0.524 0.286 0.068 0.5 0.023 9°22' 1°17' 0.115 1.05x10-3 ML

N471 Br.13 14,7-15,5 UD10 41.6 2.64 1.74 1.23 95.83 53.4 1.15 39.70 25.70 14.00 1.136 0.080 8°36' 0.96x10-3 ML

N472 Br.13 17,7-18,5 UD12 53.3 2.65 1.61 1.05 92.68 60.4 1.52 49.10 29.80 19.30 1.218 0.052 6°1' 1.08x10-3 ML

Average A 47.3 2.64 1.69 1.15 96.40 56.0 1.30 44.00 28.50 15.50 1.210 0.060 7o26'Layer 13-4 (SC): N473 Br.13 19,2-20,0 UD13 32.5 2.6 1.72 1.3 84.50 50.0 1.00 36.50 26.20 10.30 0.612 0.074 13°9' 17°17' 0.086 31°41' 0.071 0.33x10-2 SCBrownish grey clayey SAND N474 Br.13 22,2-23,0 UD15 31.2 2.61 1.74 1.33 84.65 49.0 0.96 34.50 24.80 9.70 0.660 2.979 0.189 0.046 0.8 0.034 17°4' 1°12' 0.339 0.44x10-2 SC

N475 Br.13 23,7-24,5 UD16 26.2 2.65 1.83 1.45 83.85 45.3 0.83 30.10 21.60 8.50 0.541 0.040 18°29' 0.48x10-2 SC

Average A 30 2.62 1.76 1.35 83.50 48.0 0.94 33.70 24.20 9.50 0.610 0.050 16o17'Layer 13-5 (CL): N476 Br.13 26,7-27,5 UD18 48.1 2.67 1.54 1.04 81.96 61.0 1.57 45.40 24.50 20.90 1.129 0.069 7°34' 1.49x10-7 CLBlackish grey lean CLAY Average A 48.1 2.67 1.54 1.04 81.96 61.0 1.57 45.40 24.50 20.90 1.129 0.070 7°34'Layer 13-6 (SP): N476A Br.13 29,0-29,45 D1 1.45x10-1 SPWhitish grey POORLY - GRADEDSAND N476B Br.13 30,5-30,95 D2 1.42x10-1 SP

Average A

No.Borehol

eSampleDepth

SampleName Group name

Type UUPermeability Soil classification & comments

TCVN 5747-1993Int. friction

angleCohesion

Int. frictionangle

CohesionInt. friction

angleCohesion

Groupsymbol

Type CU

Coeff. ofconsoli.

Compression index

Expansionindex

Yieldstress ofconsoli


VoidRatio

Atterberglimit

Plasticlimit

Plasticity index

Liquidityindex

Consolidation test

Blackish grey silt with sand.

Brownish grey silt with sand.




Brownish grey clayey sand.




Whitish grey poorly - graded sand.

Whitish grey poorly - graded sand.



Blackish grey lean clay.

Name of layer (4)



Wet unitweight

Dry unitweight

Deg. ofsatu-ration

Porosity


.



2-27 2-27


Figure 2.2.13 Boring Log; Br-1


2-28





2-29 2-29




2-30





2-31 2-31




2-32





2-33 2-33




2-34

2.3 Discussion on Results of Boring Investigation and Soil Testing: North Section

1) General Properties of Soil Samples

2.67 The main objective of the soil investigation was to obtain soil properties of clay layer on the HSR route (see Figure 2.3.1); They are used in estimation of consolidation behavior due to embankment, or to find a bearing stratum and depth for viaduct foundations because a condition of the stratum is regulated as that of over 5m thickness with over 50 blow counts of the SPT.

2.68 Locations of the sampling, borehole tests along the planned HSR route and location coordinates of the field tests are shown in Table 2.3.1 and Table 2.3.2 in the previous section, 2.2.


Figure 2.3.1 Geological Map and the Alignment of New HSR: North Section



2-35 2-35

2.69 Figure 2.3.6 to Figure 2.3.12 show the borehole logs for each borehole site, in which relationships of N-values of the SPT, physical properties, such as natural water content (wn), liquid limit (wL), plastic limit (wp) or the liquid index (IL), against depth can be seen.

2.70 In the diagram of relationships between N-value and depth, the blue vertical solid line shows a boundary of "N-value<4", which is a class limit for "Very soft clay". And the red solid line in the diagram of relationships between IL and depth, IL >80%,shows the boundary for "Sensitive clay".

2.71 In Table 2.3.1, layers of "Very soft clay" and that of "Sensitive clay" are listed. Over 10m thick layers of very soft clay are found in the area from Nocg Hoi to Nam Dinh via Phu ly, and that from Nam Dinh to Ninh Binh (Br-1, 4 and 6). In the vicinity of Vinh (Br-13) alluvial clay layers of surface deposit are also classified into "sensitive soft clay". It was found that most of the layers of "very soft clay" overlap those of the "sensitive clay". Most of them can be classified into silt (M) or clay with low liquid limit (CL).

Table 2.3.1 List of Layers of Very Soft Clay, Sensitive Clay and Condition of Consolidation

Br. No. Depth (m)Very soft Clay layerGL-m (thicknes m)

IL>80%(=[wn-wp]/[wL-wp],

m)

Soilclassification

Consolidation claylayer (m)

Soilclassification

Depth of bearingstrata (m)

2.0-13.8(11.8) OH 1.2-13.8（12.6, D） OH

19.0-23.4(4.4) ML-MH 16.1-27.3(11.2, D) ML-MH

2.-6.0(4.0) 20.45-27.2(6.75) CL 0.7-6.0(5.3, D) MH

13.5-40.0(26.5) 30.95-35.45(4.5) CL 13.4-71.8(58.4, D) CL

ー 47.6-51.23(3.63) CH ーー

2.1-6(3.9) 1.8-5.9(4.1) ML-MH ML-MH

12.0-24.0(12.0) 9.3-26.8(17.5) ML-MH,CL CL,MH

8 50.33 2.1-7.6(5.5) 2.0-7.3(5.3) MH 1.5-32.7（31.2, S） MH-CL 41.79 59.42 1.6-4.05(2.45) 0.4-3.8(3.4) MH 0.0-39.9(39.9, D) MH,CL 54.712 43.45 2.0-7.9(5.9) 4.1-7.9(3.8) ML-CL 4.1-38.9（34.8, S） ML-CL 38.9

2.0-19(17.0) 0.9-19(18) ML 0.9-28.3(27.4, S) ML,SC

24-28.3(4.3) 24.9-28.3(3.4) CL ーー31.513

1.5-32.4 （30.9, S）

**: Soil Classification(OH, ML-MH. MH, CL, MH-CL, SC)*: S=single drainage of consoilidaiton, D=double drainage of consoildatio

51.42

36.45

4

6

62.9

71.8

46.8

76.65

67.45 1.8-25.0(23.2)1

consolidation


2.72 At Br-1 (Nogc Hoi), a ground surface to a depth of GL-13.8m is observed an organic clay layer with high liquid limit (OH). For these types of clayey ground, it is known that potential difficulties are matter of concern in the construction works, such as large settlement or deformation problems of ground, and sometimes failure problems of embankment or that of excavated creeks/collapse of drilling boreholes for viaduct foundations etc.. Therefore, it is a required condition to carry out more precise geological investigation, precise soil testing and careful design of structures to be placed on/into the ground based on results of geological investigation.

2.73 Sedimented clay layers at the area of Nghia Trang, Thanh Hoa, Dien Trung (Br-8, 9, 12), with several meters of alluvial layers, also classified into very soft clay. However, embankments can be constructed safely under a condition that countermeasure techniques for improvement are taken related to the surface soft clay layers properly, as the layers are not so thick as that near Nam Dinh or Ninh Binh, and clayey layers


2-36

sedimented underneath of that layers are classified into the diluvial deposit which shows over four blow counts of the SPT.

2.74 In a column of "consolidation clay layer" in Table.2.3.1, the potential depth of consolidation layers is shown with symbol letters of "D" or "S", where letter "D" stands for "double drainage consolidation condition" and letter "S" stands for "single drainage consolidation condition", which is estimated from sedimented strata condition observed from borehole tests. It is known that consolidation term under single drainage condition, S, exceeds four times of that under the double drainage condition, D.

2.75 The last column of the table shows the depth of a bearing stratum for pile foundations estimated. It was found that the deepest depth of them is GL-72m at Br-4 at Nam Dinh, and the shallowest depth of that is GL-31m at Br-13 at Vinh, though the depth is, in general speaking, rather deep for the pile foundation.

2) Properties of Consolidarion of the Soil

2.76 Figure 2.3.2 shows relationships of the compression index, Cc, against the liquid limit, wL. Plots of the data shows a trend where the coefficient of Cc increases according to increase of the wL, though much scatter is observed in the data. The straight red line in the diagram shows a regression curve of the relationships of the data (see Eq.(2.3.1)), and the dashed line in black shows the relationship of Cc and wL (presented by Skempton;see Eq.(2.3.2)). It can be seen that the two regression curves show a small difference.

2.77 ◎Regression curves for relationships between the Cc and wL:

2.78 ①Data obtained from the borehole tests for the north section of Vietnam:

Cc= - 0.2661＋0.01253･wL(%) （2.3.1）

2.79 ②Equation presented by Skempton:

Cc＝ - 0.09＋0.009･wL(%) （2.3.2）

2.80 Figure 2.3.3 shows relationships of the coefficient of consolidation, Cv, to wL, showing a trend that Cv becomes smaller when wL becomes higher, though not small scatters are observed, and the relationships of variables is expressed by the following regression curve.

Cv＝5.852×exp[-0.03477･wL(%)]×(10-3 cm2/s) (2.3.3)

2.81 Figure 2.3.4 shows the relationship of the compression index, Cc, against the expansion index, Cs. This relationship is expressed in Eq.(2.3.4) by a regression curve. The ratio between Cc against Cs is expressed in a ratio of 1 :0.2, which ratio is the value of a typical normally consolidated clay.

Cs=0.01624+0.20079･Cc （2.3.4）

2.82 Figure 2.3.5 shows a diagram of the consolidation yield stress in the effective stress, pc, against depth for data from all of the borehole tests. In the diagram, two lines were added to show effective stress distribution in the ground, which is calculated assuming the submerged unit weigh of soil as γ'=0.6 or 0.7 t/m3. Observed values of the pc are distributed in the vicinity of the two curves in range of depth of less than GL-20m, though the gap between the pc and the auxiliary lines over the range of depth deeper than



2-37 2-37

GL-20 m. Based on the above discussion, it can be assumed there will be normal consolidation condition for the clay stratum at the Br-9 site.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

20 30 40 50 60 70

Cc

y = -0.26614 + 0.012528x R= 0.72214

Cc

wL (%)

Cc =0.009(WL‐10）

Figure 2.3.2 Relationships of Cc against WL (North Part)

0.1

1

10

20 30 40 50 60 70

Cv cm/s×10~-3

y = 5.8517 * e^(-0.034769x) R= 0.274

Cv (cm2/s ×

10^-3)

wL (%)

Figure 2.3.3 Relationships of Cv against WL (North Part)

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Cs

y = 0.016242 + 0.20079x R= 0.8906

Cs

Cc Figure 2.3.4 Relationships of CS against

CC (North Part)

0

10

20

30

40

50

600 1 2 3 4 5

depth m

GL- m

pc (kgf/cm2)

Figure 2.3.5 Relationships of PC against depth (North Part)


3) Settlement of the Br-9 Site Due to Construction of an Embankment

2.83 Thirty nine percent of the north route is designed to be that of embankment type, and about 40% of it will be constructed in the Thanh Hoa province area. Therefore, trial calculation of consolidation was carried out using data of the Br-9 site.

2.84 First, consolidation parameters, the Cc (the compression index) and Cv (the coefficient of consolidation) were evaluated using Eq. (2.3.1) and (2.3.3) based on


2-38

observed value of the wL (the liquid limit), which are shown in Table 2.3.2. Observed coefficient of the Cc and Cv can be seen in the margin of the table. The right column of the table shows the pc (the consolidation yield stress) obtained from consolidation tests.

2.85 Next, the over consolidation ratio (OCR=pc/p) at this site is described as follows; The parameter, pc, is observed for two samples from a depth of GL-2.8m and GL-13.3m at the Br-9 site, and is compared to the overburden effective pressure, p',

2.86 ①At GL-2.8m, observed pc=4.6 tf/m2(=0.46 kgf/m2≒46kN/m2)

2.87 Estimated overburden pressure (effective stress) at a depth of 2.8m, p', is;

→ p'=2.1m×1.65t/m3+0.7×0.65 tf/m2 =3.92 tf/m2 (≒39.2kN/m2)

2.88 Here, as the water table at the Br-9 site was observed at a depth of GL-2.1m, unit density in the calculation was assumed as γsat=1.65t/m3 from the ground surface to a depth of GL-2.1m, and γ'=0.65t/m3 from a depth of GL-2.1m to GL-2.8m. Then, the OCR was obtained as OCR=4.6/3.92=1.17.

2.89 ②At GL-13.3m, observed pc=9.7 tf/m2 (≒97 kN/m2)

2.90 Estimated overburden pressure (effective stress) at a depth of 13.3m, p', is;

→ p'=2.1m×1.65＋11.2m×0.65t/m3=10.75 tf/m2 (≒107.5kN/m2)

2.91 Here, as the water table at the site was observed at a depth of GL-2.1 m, unit density in the calculation was assumed as γsat=1.65t/m3 from the ground surface to a depth of GL-2.1 m, and γ'=0.65t/m3 is assumed from a depth of GL-2.1m to GL-13.3 m. Then, the OCR was obtained as OCR= 9.7/10.75=0.90.

2.92 The OCR obtained at a depth of GL-2.8m and GL-13.3m were close to the value of unity, namely, it is can be assumed that the clayey strata at the Br-9 site are under normally consolidation condition.

2.93 Table 2.3.2 (1) and (2) show processes of calculation of settlement due to consolidation of embankment with a height of 6m (Table 2.3.2 (1)) and 9m (Table 2.3.3 (2)) respectively. The last two columns shows a trial calculation for the "embankment +extra banking", which is banked to compensate for settlement of the ground due to construction of the embankment, namely consolidated height of the "embankment +extra banking" coincides with the designed height of the embankment. In the calculation, unit weight of embankment was assumed as γt= 2 t/m3.

2.94 Table 2.3.4 shows settlements of the embankment (H=6 m and 9 m) and that with an extra banking. It is necessary to be aware about deformation influence margin of the embankment due to construction of the embankment, namely deformation of field or rice paddy around the constructed embankment.



2-39 2-39

Table 2.3.2 Physical Properties and Parameters of the Cv and Cc

Br-9depth m1st layer (GL-0～5.5m)

1.3 51.8 55.9 33.4 81.78 0.84 0.43 -2.8 71.6 68.7 44.4 111.93 0.54 0.59 0.464.3 20.8 30.2 17.3 27.13 [2.05] [0.11] -

H1=5 .5m 0.69 0 .512nd layer (GL-5 .5～20 .3m)

7.3 30.9 41.5 21.2 47.78 1.38 0.25 -10.75 36.7 44.6 23.5 62.56 1.24 0.29 -13.3 28.9 43.1 22.3 31.73 1.31 0.27 0.9716.3 26.8 40.5 20.9 30.10 1.43 0.24 -19.3 28.7 44.1 22.8 27.70 1.26 0.29 -

H2=14 .8ｍ 1.33 0 .273rd layer (20 .3～39 .9m)

22.3 24.2 38.9 19.7 23.44 1.51 0.22 -29.8 24.9 40.9 21.2 18.78 1.41 0.25 -32.8 25.1 41.8 20.4 21.96 1.37 0.26 -35.8 27.5 43.1 23.2 21.61 1.31 0.27 -

H4=12 .2m 1 .36 0 .26

wL　% wp　% IL　%Cv

cm2/s･10-3

Observed data, GL-2.8m (Cv=0.37×10-3 cm2/s, Cc=0.67)

GL-13.3m (Cv=0.827×10-3 cm2/s, Cc=0.197)

wn　% Ccpc

kgf/cm2


Table 2.3.3 (1) Trial Calculation of Settlement for a 6 m Height Embankment

[1]

p'0+⊿p Si (ｍ)p'0+⊿

pSi (ｍ)

0.0 1.65 0.00

1st layer 5.5 2.3 1.65 3.71 61.7 2.7 1.64 2.64 0.51 15.71 0.67 20.7 0.795.5 0.65 5.83

2nd layer 14.8 12.9 0.65 10.64 30.4 2.7 0.82 1.82 0.27 22.64 0.72 27.6 0.9120.3 0.65 15.45

3rd layer 7.4 24.0 0.65 17.85 22.1 2.7 0.59 1.59 0.22 29.85 0.23 34.9 0.3027.7 0.65 20.26

4th layer 12.2 33.8 0.65 24.22 25.8 2.7 0.70 1.70 0.26 36.22 0.33 41.2 0.4339.9 0.65 28.19

Total S(6m)= 1.95ｍ S(6+2.5m) = 2.43m

Increase load by embankment : ⊿ｐ＝6m×2.0ｔｆ/ｍ2＝12ｔｆ/ｍ, ⊿p=8.5m×2.0＝17tf/m2

Increase settlement of each layer : Si=⊿H×(Cc/f0)×log([p'0＋⊿ｐ]/p'0）e0=wn×Gs×γw　：γw=1.0t/m3, Extra b.=Extara banking

Depthm

H (emb)=6+2.5H (emb) .=6mConsolidation layers

（ｍ）

f0=1+e0

Cc ⊿H mｐ'0

t f/m2wn %

γ'/γttf/m2

Embank. H H + Extra b.

e0Gs


Table 2.3.4 (2) Trial Calculation of Settlement for a 9 m Height Embankment

[2]

p'0+⊿p Si (ｍ)p'0+⊿

pSi (ｍ)

0.0 1.65 0.00

1st layer 5.5 2.3 1.65 3.71 61.7 2.7 1.64 2.64 0.51 21.71 0.81 27.7 0.935.5 0.65 5.83

2nd layer 14.8 12.9 0.65 10.64 30.4 2.7 0.82 1.82 0.27 28.64 0.94 34.6 1.1320.3 0.65 15.45

3rd layer 7.4 24.0 0.65 17.85 22.1 2.7 0.59 1.59 0.22 35.85 0.31 41.9 0.38

27.7 0.65 20.26

4th layer 12.2 33.8 0.65 24.22 25.8 2.7 0.70 1.70 0.26 42.22 0.45 48.2 0.5639.9 0.65 28.19

Total S(9m)=2.51m S (9+3m)= 3.0m

Increase load by embankment : ⊿ｐ＝9m×2.0ｔｆ/ｍ2＝18ｔｆ/ｍ, ⊿p=(9+3)m×2.0＝24tf/m2Increase settlement of each layer : Si=⊿H×(Cc/f0)×log([p'0＋⊿ｐ]/p'0）

e0=wn×Gs×γw　：γw=1.0t/m3, Extra b.=Extara banking

Consolidation layers

（ｍ） ⊿H m

Depthm

ｐ'0t f/m2

wn %H

Embank. H H + Extra b.

γ'/γttf/m2

Gs e0f0=1+e

0Cc

H (emb) .=9m



2-40

Table 2.3.5 Settlement Due to Embankment

(m) (cm) (m) (cm) (m)

6 195 2.5 243 6.079 251 3.0 300 9.00

H1, H2= height, S1, S2=settlementG.H. after consoli=grand height after consolidation

S1 due toembankme

H2 ofextra b.

S2 dueto

H1 ofembankment

G.H afterconsoli.


4) Estimation of Consolidation Time

2.95 Elapsed time of consolidation due to construction of the embankment was estimated based on data obtained from the borehole test at the Br-9 site, in which the degree of consolidation, Uε, was set to Uε=90% and 95%. The strata, from the surface of ground to GL-39.9m at the Br-9 site is composed of layers classified as MH (silt with the high liquid limit) and CL (clay with the low liquid limit), In addition pore-water of the layers released due to consolidation can be drained from both ends of the clay layers (double drainage system, namely in the "D" condition).

2.96 The layers at the site were divided into three layer categories with different coefficients of consolidation, namely, Cv, which is shown in Table 2.3.5. A simplified method to estimate consolidation time was used, here. It is no matter to say that accurate results of the consolidation time would be obtained using the theory of multi layers consolidation.

2.97 An outline of the simplified method is as follows;

2.98 First, Cv parameters for each layer (see the table), and the average value of the whole consolidation layers was calculated using the weighted mean method (see Eq. (2.3.5)).

Cv"(average)= (Hi×Cvi)/（ΣHi) i=1 to 3 (2.3.5)

2.99 The average value of the layers at the site, Cv", is estimated as Cv"＝1.26×10-3

cm2/s.

2.100 Second, the multi-Cv layers system are assumed as a single layer system with parameter of the Cv". Third, find the time factor, Tv, based on the degree of consolidation, Uε,in order to estimate consolidation time. Table 2.3.6 shows the time factor of each Uε. As the ultimate strain of settlement (εf) for a case of 6m or 9m embankment becomes 6.1 or 7.5% (=243/3,990 or 300/3,990), the parameter, Tv, of εf=5% is used in the following calculation.



2-41 2-41

Table 2.3.6 Estimation of Cv

Br-9

depth m

1st layer (GL-0～5.5m)

1.3 0.84

2.8 0.54

4.3 [2.05]

H1=5 .5m 0 .69

2nd layer (GL-5 .5～20 .3m)

7.3 1.38

10.75 1.24

13.3 1.31

16.3 1.43

19.3 1.26

H2=14 .8ｍ 1.33

3rd & 4th layer (20 .3～39 .9m)

22.3 1.51

29.8 1.41

32.8 1.37

35.8 1.31

H3+4=19 .6m 1 .36

1 .26 cm2/s×10^-3

Av. of Cv=

Cvcm2/s･10-3


Table 2.3.7 Tv for each εf

Uε εf=0％ εf=5％ εf=10%

90% 0.848 0.800 0.71095% 1.200 1.087 1.000


2.101 Elapsed time of consolidation is estimated using Eq.(2.3.6).

t（sec） =[Tv・(H/2)2/Cv] (2.3.6)

2.102 ①For consolidation time until Uε=90%

t(sec)=0.8×（3990/2）2/1.26×10-3 cm2/s → 80.1 yer.

2.103 ②For consolidation time until Uε＝95%

t(sec)=1.087×（3990/2）2/1.26×10-3 cm2/s → 108.9 yer.

2.104 It is concluded that the embankment construction for the HSR can not be achieved without using a countermeasure to improve consolidation time of the ground because of continuation of the consolidation for a very long time.

5) Discussion on Countermeasure to Accelerate Consolidation of the Clay Layers

2.105 Here, application of the sand-drained method, which is a typical countermeasure in order to accelerate consolidation of clayey layers, is discussed.

2.106 Table 2.3.7 shows a result of trial calculation for the sand drain method at the site. Diameter of the sand drain was assumed as φ30cm, and an "alternate alignment of the drain piles" and a "square alignment" were discussed as trial conditions. The effective drainage diameter, de, is assumed as sizes shown in Eq. (2.3.7).


2-42

2.107 An alternate alignment: de=1.05d, a square alignment； de=1.128d (2.3.7)

2.108 Here, a letter, 'd', reffers to the distance between diameter centers of the sand drain piles.

2.109 In the trial calculation, the horizontal coefficient of consolidation, Ch, is assumed to be two times that of the Cv, namely, the horizontal permeability of the layers, kh, is assumed to be two times that of the vertical permeability, kv, which is obtained from the consolidation test.

2.110 The time factor for horizontal consolidation at Uε=90%, a parameter Th(90%), for

each alignment of sand drain piles is obtained from a diagram of the Th～Uε relationships.

Table 2.3.8 shows the calculation process for design of the sand drain method. In the table, elapsed time for consolidation is calculated using Eq.(2.3.8).

t（sec） =[Th・(de)2/Ch] (2.3.8)

2.111 It is estimated that the consolidation time will be 2.5 months to 5 months depending on the alignment of sand drain piles and diameter of the drain, which is shown in the table.

Table 2.3.8 Trial calculation of settlement using the sand drain method

Br-9alignmnet

200 210 0.00252 7.0 0.37 6475000 74.9250 262.5 0.00252 8.8 0.44 12031250 139.3200 225.6 0.00252 7.5 0.39 7876663 91.225 282 0.00252 9.4 0.46 14516286 168.0

*1:align. of d.=alignment of sand drain piles, alte a=an alternate alignment ofsand drain piles, squre=a aquare alignment of sand drain piles

*2:de:①square alignment→de=1.05d, ②altenate alignment → de=1.128d, *3:dw=φ30cm, Ch=2*Cv

altenate

squre

t (sec) t (day)Ch

(cm2/s)r (cm) de (cm) n=de/dw Th (90%)


6) Discussion Regard To Disasters In Vietnam

2.112 Natural disasters in Vietnam, such as slope failure or collapse, falling rocks, flooding and earthquake, are not investigated in this report. Although, they should be taken into consideration of countermeasures in order to prevent or minimize injury from such disasters. It is also necessary to establish regulations with regard to these disasters.



2-43 2-43


Figure 2.3.6 Boring Log and Physical Properties: Br-1




2-44







2-45 2-45






2-46





3-1 3-1

3 GEOLOGICAL SURVEY FOR SOUTH SECTION

3.1 Site Survey in South Section

3.1 Site investigation of the southern route of HSR from HCMC to Nha Trang was carried out in September 2011 to inspect regional topography, geology, adjustability and problems of railway route and structures from various view points.

1) Site Survey of Geology and Topography from HCMC to Nha Trang

3.2 Geology and topography from HCMA to Nha Trang is roughly divided into two major regions: lowland area from HCMC to Long Thanh international airport and the highland area from Long Thanh to Nha Trang.

3.3 Lowland, famous as the Mekong Delta is spreading over HCMC area and a part of Dong Nai province bordered by the Dong Nai River. Soft soils are widely distributed in this Mekong Delta.

3.4 On the other hand, Basalt Plateau and mountains are distributed from Long Thanh to Nha Trang. A part of this interval is the costal terrace with dune sand spreading along to seashore from Phan Thiet to Chi Cong. The area of Chi Cong to Nha Trang is characterized high mountains plunging to the sea, narrow plane land at the sea shore and lagoons.

3.5 Geology of mountain area is mainly composed of sedimentary rocks and volcanic rocks of Mesozoic Era.

3.6 JICA Study Team carried out a site survey along the planned HSR Route in the South Section and divided the HCMC–Nha Trang area into sixteen sections to explain the detail characteristic of south section geology. The following table shows the typical geology of each section.

Table 3.1.1 Typical Geology from HCMC to Nha Trang

No. Section Land Use Geology Description

1 Thu Thiem to National Highway QL51

Houses and rice field

Alluvial deposits of Dong Nai river. Thickness of soft soil (sand, silt, clay) is estimated more than 40m.

2 National Highway QL51 to Long Thanh Airport

Plantation area and land development (partly)

Clay sand & Sand (0m~ nearly 30m from ground surface) and weathered basalt of Xuan Loc Formation (βQIIxl) is deposited beneath clay layers.

Soil with reddish brown color is widely distributed on the ground surface in this area. Surface soil will be muddy when it was saturated with water.

3 Long Thanh Airport to Province Road TL765

Plateau with Rubber and Fruits plantation

Forming basalt plateau. Laterite (surface) and Basalt of Xuan Loc

Formation (βQIIxl).

Surface soil is mainly composed of laterite with red color. Weathered basalt is observed at the river bed of small river in small village

4 Province Road TL765 to National Highway QL55

Mountain, Plantation area (fruits) and Rice Field.

Laterite (surface). Diorite of Deo Ca Complex (γKdc) forms in

mountain area. Shale, sand stone, siltstone of La Nga Formation (J2ln).

Basalt of Xuan Loc Formation (βQIIxl) is partially distributed.

High mountain area is mainly composed with granite and diorite. Sandstone and shale are observed at the roadbed and the slope of local road.

5 National Highway QL55 to Province Road 712

Plantation area of fruits and crops.

Shale, sand stone, siltstone of La Nga Formation (J2ln), biotite granite of Deo Ca Complex (γKdc) and sand, pebble, clay of Thu Duc Formation (Pleistocene).

Granite of Ca Na Complex (Knt) is partially deposited.

Geology of mountain area is mainly composed of hard rock.

White sand deposited down stream of Phan river. Geology at the abutment of the Phan river bridge of NH.1 is estimated sand, clay, gravel of


3-2


Quaternary deposit. 6 Province Road 712

to Phan Thiet Rice field & Plantation area (fruits).

Fine to medium grain white-gray sand, silt, clay of Holocene deposit (QIV3).

Brownish-red and brownish-yellow fine grained sand (Holocene: Q).

Biotite granite of Deo Ca Complex (γKdc) and Granite of Ca Na Complex (Knt)

Coastal Terrace spreading along to the sea shore. Fine grain white sand is widely distributed on the coastal terrace and forming sand hill. Bearing capacity of white sand seems high, but the cohesion of white sand is estimated very low and will easily flow out by the rain fall.

7 Phan Thiet City area Clay, plant humus, peat of Holocene (QIV2-3). Pebble, granule, sand and clay of Cu Chi Formation (aQIII3cc).

Biotite granite (γKdc )

Sandy and silty layer, of which bearing capacity seems enough for pillar foundation, is distributed at the bank of Ca Ty river.

8 Phan Thiet to Phan Ri Cua

Sand hill of coastal terrace. Quarry and Wind Power Plant.

Greyish-white sand with low coefficient of uniformity (Holocene: QIII3).

Brownish-yellow and brownish-red sand (Undivided Quaternary: Q). Dacite of Nha Trang Formation (Knt).

Greyish-white sand and Brownish-yellow and brownish-red sand (laterite) occupy nearly whole area of the coastal terrace. Both of these layers are easily eroded by rain fall and gully erosion valleys are formed elsewhere.

Civil works of this area, such as cut and embankment, etc., must be taken care to the slope stability.

9 Phan Ri Cua to Chi Cong

Cemetery, Wind Power Plant.

Sand, silt, cobble of Holocene (amQIV2) along to the Luy river.

White sand, silt and cobble of the Pleistocene (amQII-III) at the center area and forming sand hill with 4 km wide, 7 km long.

Rhyolite, dacite (Knt) and pink biotite granite (Deo Ca Complex(γξKdc2)) forming low hill.

White sand forming the coastal sand hill is cohesion less and coefficient of uniformity will be low. Wind power plant and large cemetery area is developed in this area.

The mountain side is mainly composed of hard rocks of Nha Trang Formation. Elevations of the top of mountains are less than 100m.

10 Chi Cong to Vinh Hao

Salt farms are developed at the seashore.

Sand, silt, cobble of Holocene (amQIV2) along to the Long Song river. Yellowish gray quartz sand, silt and a cobble of the Pleistocene (amQII-III).

Rhyolite, dacite of Nha Trang Formation and pink biotite granite of Deo Ca Complex (γξKdc2) at the mountain side.

Elevation of the low land is around 5m or lower and will be sorted to the flood area.

Short cut by the several numbers of tunnels is recommended to avoid the small radius curve.

11 Vinh Hao to Nhi Ha Salt farms are developing along to the small river in Ca Na.

Grano-syanite with pink color, biotite granite of Deo Ca Complex (γξKdc2) is forming mountain. Sand, silt and cobble in the Pleistocene (mQII-III) at plain land.

Long tunnel about 10 km is recommended to avoid the narrow area where NH1 and railway are occupying almost all of the area, and also to avoid rock fall and rock fall from the surrounding mountains.

12 Nhi Ha to Thap Cham

Agriculture area and large cemetery

Grano-syanite with pink color, biotite granite of Deo Ca Complex (γξKdc2) in mountain area. Sand, silt and cobble in the Pleistocene (mQII-III) at plain land.

Sand, silt and cobble in Holocene is deposited along to the Dinh Kinh river and is forming alluvial fan.

Amount of the groundwater seems too less compared to the estimated amount of the rainfall in the mountain area. Underflow water spring out from the bottom of a canal constructed in the salt farm. This suggests that the mountain area is reserving a certain amount of water.

13 Thap Cham to Cam Ranh

Thap Cham town and agriculture area

Plain land: Sand, silt and cobble in Pleistocene and Holocene.

East mountain: grano-syanite with pink color, biotite granite of Deo Ca Complex (γξKdc2).

West mountain: Biotite-hornblende granite of Dinh Quan Complex (γδJ3dq)

Near to Cam Ranh: Andecite and dacite of Deo Bao Loc Formation (J3dbl) and sedimentary rocks (shale, slate) of La Nga Formation (J2ln)

Plain land around Thap Cham town is classified as the hazardous area of flood.New railway route shall be planned near to the existing railway route. However, the width of the valley is not enough in several places and tunnels will be necessary.Sedimentary rock of La Nga Formation (silt stone & shale alteration) is observed beneath rhyolite of Deo Bao Loc Formation at earth dam site. Thickness of surface soil and the weathered zone are estimated 3m to 5m.



3-3 3-3


14 Cam Ranh and Thuy Trieu Lagoon

Cam Ranh town, military base, fishery and agriculture

Calcareous gravel stone, coral limestone, sand , silt of upper Pleistocene, sand, gravel of Holocene is deposited on plain land.

Biotite-hornblende granite in Dinh Quan Complex (γδJ3dq) and rhyolite, dacite of Nha Trang Formation (Knt) at west mountain. Grano- Syanite, granite of Deo Ca Complex is forming mountain at center of plain land.

The plain land along to the seashore is shared by the military base. Further development of the plain land and the Cam Ranh peninsula for the new railway construction shall be difficult.

Hard rocks are distributed in the mountain area at the center and westside of the Cam Ranh town. Several numbers of short tunnels are recommended.

15 Thuy Trieu Lagoon to Nha Trang City

Nha Tarng City and mountain area. Resort area under construction near to lagoon. Land development for housing.

Sand, silt, cobble and clay of Holocene are deposited on the plain land in Nha Trang city and buried lagoon.

Mountain area is mainly composed of rhyolite, dacite of Nha Trang Formation (Knt) and granite of Ca Na Complex (γK2cn). Diorite of Dinh Quan Complex (γδJ3dq).

Boring cores drilled at the north end of lagoon shows hard and intact rhyolite beneath the talus deposit. Diameter of the core is 10cm and RQD is estimated more than 95%.

Several numbers of rhyolite quarry site are observed at the north slope of the mountain area.

A wide swampy area, nearly 3 km x 3 km, is spreading in the Quan Truong river leading to Nha Trang sea through Hon Ro Port in Cua Be, Vinh Truong.

16 Nha Trang City City area Sand, silt, cobble and clay of Holocene is deposited on the plain land.

North and South mountains are mainly composed of rhyolite, dacite of Nha Trang Formation (Knt).

Diorite of Deo Ca Complex (γKdc) is intruded along the left bank of Cai river.

West mountain is composed of andesite and dacite of Deo Bao Loc Formation (J3dbl).

Many land development project are proceeding around the Nha Trang City.

Some of them are filling a swampy area. Thickness of embankment in swampy area is estimated 2m. Alignment at shoulder of the slope of embankment shows undulation that suggests the settlement of embankment.

Soil condition of the alluvial deposits should be confirmed by several numbers of bored hole.


2) Major Issues for Civil Works in Each Section

(1) Thu Thiem Station to Dong Nai River

3.7 Thu Thiem station and HCMC Depot Area is planned in this section. Soft soils such as loose sand, silt and clay layers are deposited from ground surface to nearly G.L.-70m. Bridge and viaducts of HCMC Highway under construction is designed with pile foundation and various methods to accelerate the consolidation of the ground. The confirmations of the bearing capacity of the strata were carefully executed during the construction time. Design of HCMC Highway structures will be good example for the design of the structures of the Thu Thiem terminal as well as the HCMC Depot.

3.8 Soil condition of the Depot Area is estimated almost same with Thu Thiem Station. As the settlement of ground surface in this area will occur, an advanced drainage system should be considered to accelerate ground settlement.


3-4

Swampy area near Thu Thiem station area Drain of Long Thanh–Dau Giay Express

Highway Source: JICA Study Team

Figure 3.1.1 Geological Conditions in Thu Thiem–Dong Nai River Area

(2) Long Thanh Station

3.9 Long Thanh Station in Long Thanh International Airport (LTIA) is planned as shallow trench excavated from ground surface. Topography in this area is found with basalt distributed from the east and a basalt plateau is formed underlying the whole area. Open cut excavation shall meet the weathered rock of basalt in shallow depth.

Express Highway near LTIA under

construction with embankment on the laterite Location of LTIA in the middle of rubber fields


Figure 3.1.2 Geological Conditions near LTIA Area

(3) Phan Thiet to Phan Ri Cua Section

3.10 Large desert of costal terrace is spreading along to seashore. Maximum width and length of the desert are estimated approximately 25 km, 45 km respectively. Isolated mountains developed for the quarry site exists near to the National Highway 1A and low height bushes are scattered on the ground surface of desert area. Central part of the desert area is composed of unstable sand dunes.

3.11 Two alternative HSR routes are planned in this section. One is passing straight through the desert area and the other is detouring toward north almost parallel with National Highway 1A.

3.12 Railway structures are mainly planned as cut and embankment. Sand dunes are unstable and self-standing time of slope is near equal zero and the slope protection shall be a reason for high construction cost.

3.13 Straight route shall absolutely encounter many difficulties for the construction of HSR. Detouring route shall also have the same issue but will be better than the straight route as the location is farther from the seashore and near to the National



3-5 3-5

Highway 1A where the sand is more stable.

White Sand Area near Phan Thiet Gully of White Sand Area

Coastal Terrace at Bau Trang Lake Side Gully Erosion of laterite Source: JICA Study Team

Figure 3.1.3 Geological Conditions in Phan Thiet–Phan Ri Cua Area

(4) Vinh Hao to Nhi Ha Section

3.14 In this area, a high mountain plunges to the Ca Na beach where the National Highway No.1 and the existing railway is passing through very narrow plain along the seashore. Distance from existing railway located at the toe of mountain to the sea is only 400m and there is no more sufficient space for the HSR Route.

3.15 Geology of the high mountain in this area is composed of granite and intrusive of Mesozoic Era. Unfavorable tectonic structures such as folding, large fault and crushed zone were not observed during the site survey. However, boiling of water from the river bed of small canal was observed near Phuoc Minh area. This phenomenon suggests that considerable amount of water is reserved in the mountain.

3.16 HSR Route shall pass through this mountain area by the long tunnel. Environmental assessment, especially drought problem, should be investigated.


3-6

Blocky Rock of Granite Forming Steep Slope in Ca Na area

Cubic Joint Open Crack

Existing Railway in Narrow Plain in Ca Na


Figure 3.1.4 Geological Conditions near Ca Na Area

(5) Nha Trang City Section

3.17 Nha Trang city was developed at the river mouth of Cai River. Nha Trang Station and Nha Trang Depot area for HSR are planned in this section.

3.18 From the result of topography analysis by Google Earth, the central area of Nha Trang City locates on the sandbar and an old lagoon at the toe of southern mountain has been partially filled for the land development. In this land development area, the shoulder of the embankment under construction was found undulated, which means there may be an equal ground settlement.

3.19 Nha Trang Station of HSR and Nha Trang Depot Area are planned at the right bank and left bank of Cai River. Alluvial deposit of Cai River is deposited in both areas. The elevation of Nha Trang Station and Depot Area are estimated less than 10m. The Depot Area is planned along the National Highway 1A in the rice field area of which the elevation is nearly 2 m lower than the road level. These areas are flood area and shall be submerged during typhoon season, however the road level of National Highway 1A was found safe for flood level in the past. Detail inspection is required for the detail design of the HSR structures.



3-7 3-7

Swampy Area at the South of Nha Trang Cai River in Nha Trang City Source: JICA Study Team

Figure 3.1.5 Geological Conditions in Nha Trang


3-8

3.2 Boring Investigation

1) Summary of Boring Investigation in South Section

3.20 JICA Study Team has carried out the boring investigation in south section in order to collect geological and geotechnical information available for the fundamental design of the bridges, tunnels, railway stations and cut & embankment, etc., for HSR route from Ho Chi Minh to Nha Trang. Major targets for the investigation are as follows;

(i) Thu Thiem Station and Depot Area

(ii) Basalt Plateau and Alluvial Deposit from Long Thanh Airport to Phan Thiet

(iii) Seashore Terrace spreading from Phan Thiet to Chi Cong

(iv) Tunnels and bridge foundations from Ca Na to Thap Cham

(v) Foundation of Thap Cham Station

(vi) Nha Trang Station and Depot Area

3.21 Totally 15 numbers of inspection boring have been carried out. Locations and details of the borings are shown in Table 3.2.1. Horizontal alignment of HSR route and location of boring overlapped on the geological map are shown in Figure 3.2.1.

Table 3.2.1 List of Boring Locations along HSR Route in South Section

No Borehole

Location Coordinates Elevation Depth

Place-Names Name Latitude Longitude (M) (M)

1 BH1 Thu Thiem Station 10°47'10.92'' 106°44'38.75'' 1.2 40.0 Thu Thiem ward, District 2, Ho Chi Minh City

2 BH2 Long Truong Depot 10°47'45.22'' 106°50'16.77'' 1.5 40.0 Long Truong ward, District 9, Ho Chi Minh City

3 BH2A Long Thanh Station 10°46'43.16'' 107°02'56.25'' 62.8 30.0 Cam Duong commune, Long Thanh district, Dong Nai province

4 BH3 White sand area near Phu Sung Village

10°53'12.85'' 107°57'48.20'' 26.3 20.0 Phu Xuan hamlet, Ham Cuong commune, Ham Thuan Nam district, Binh Thuan province

5 BH4A Ca Ty river Bridge 10°56'16.07'' 108°04'24.67'' 7.1 15.0 Xuan Tai hamlet, Phong Nam commune, Phan Thiet city, Binh Thuan province

6 BH4 Phan Thiet Station 10°56'31.50'' 108°04'49.16'' 7.5 15.0 Xuan Tai hamlet, Phong Nam commune, Phan Thiet city, Binh Thuan province

7 BH5 Reddish and white sand location

11°09'25.79'' 108°16'19.95'' 88.0 40.0 Hong Liem commune, Ham Thuan Bac district, Binh Thuan province

8 BH5A Red sand area along Pre-FS alignment

11°03'01.71'' 108°17'02.10'' 176.2 30.0 Hong Phong commune, Bac Binh district, Binh Thuan province

9 BH5B Red sand area along Pre-FS alignment

11°08'21.10'' 108°25'20.50'' 166.6 30.0 Hoa Thang commune, Bac Binh district, Binh Thuan province

10 BH6 White sand area near Chi Cong

11°11'52.18'' 108°36'44.76'' 15.0 15.0 Chi Cong commune, Tuy Phong district, Binh Thuan province

11 BH7A Ca Na Tunnel south Portal

11°20'15.14'' 108°45'55.41'' 52.0 20.0 Vinh Hao commune, Tuy Phong district, Binh Thuan province

12 BH7 Ca Na Tunnel north Portal

11°24'43.50'' 108°49'06.80'' 103.0 20.0 Nhi Ha commune, Thuan Nam district, Ninh Thuan province

13 BH8 Thap Cham Station 11°35'59.22'' 108°57'01.98'' 15.0 15.0 Do Vinh ward, Phan Rang-Thap Cham city, Ninh Thuan province

14 BH9 Nha Trang Station 12°15'16.21'' 109°09'19.07'' 4.0 40.0 Vinh Hiep commune, Nha Trang city, Khanh Hoa province

15 BH10 Nha Trang Depot 12°17'29.62'' 109°09'16.46'' 2.5 20.0 Vinh Phuong commune, Nha Trang city, Khanh Hoa province




3-9 3-9

Thu Thiem

BR-1

BR-2

BR-2A

HSR Route

Long Thanh

Phan Thiet

HSR Route

BR-3 BR-4BR-4A

Tuy PhongPhan Thiet HSR Route

BR-5

BR-5ABR-5B

BR-6

BR-7A

Thap Cham

HSR Route

BR-7 BR-8

Nha Trang

HSR Route BR-9BR-10


Figure 3.2.1 Geological Map and Location of Boring


3-10

2) Result of Boring Inspection in South Section

3.22 Planning and location of inspection boring is decided from the result of site survey executed at September 2011 considering the requirement of the railway structures along to the HSR route.

3.23 Regional geology of each boring point is referenced by the geological maps of Viet Nam issued by the Department of Geology and Minerals of Viet Nam. Borehole logging and results of soil and rock investigations are described hereunder.

(1) Boring No.1 (B.H.1)

3.24 Location of B.H.1 is along to the roadside of Dai Dong Tai Road that is recently opened, which connects Thu Thiem area and Ben Thanh (HCMC City Center). Thu Thiem Station is planned near swampy area (Figure 3.2.2) and settlement of ground surface shall be the major issue. As Thu Thiem Station area locates near the interchange of the HCMC highway which is under construction, the soil investigation data of this project shall be a useful reference.


Figure 3.2.2 Boring Location in Thu Thiem Station Area

(a) Regional Geology of B.H.1

3.25 Boring point is located at the remaining land surrounded by the Sai Gon River. Geology of this area is mainly composed of 10 m thick sand and silt layers with same organic traces deposited during middle to upper Holocene. Sand, silt and clay of lower to middle Holocene sediments are lying beneath with layers thickness of 2 m to 10 m.

(b) Result of Inspection Boring B.H.1

3.26 Grand water level is recorded as G.L. -0.8 m from the ground surface. Boring log is described as follows;

(i) Thickness of surface soil is 0.8m.

(ii) Fat clay with N≈0 containing organic substance is depositing from G.L.-0.8 m to G.L.-12.5 m and alteration of silty sand and fat clay is observed around G.L.-12 m.

(iii) Stiff clay, silty sand, lean clay is deposited at G.L.-12.5~-19 m, G.L.-19~33.5 m, G.L.-33.5~40 m, respectively. N value of those layers are recorded N=10~20.

(c) Result of Soil Tests of B.H.1



3-11 3-11

3.27 Summary of Atterberg Limit (LL, PL etc.) obtained from B.H.1 and boring data of the HCMC Highway are shown in Table 3.2.2 while the result of consolidation test in B.H.1 is shown in Table 3.2.3.

3.28 Result of soil investigation is summarized below.

(i) Liquidity Index (iL) of the fat clay calculated from Liquid Limit and Plastic Limit at depth up to G.L.-12.5 m show high value of iL=0.818, iL=0.921. These values mean that the fat clay is classified as the sensitive clay which may cause the low trafficability.

(ii) Layer 1 of Bore Log of HCMC Highway Project shows iL=1.031 which is classified as very sensitive clay. A plastic water drainage system is applied to prevent ground settlement.

(iii) Settlement of fat clay calculated from the consolidation test is 29%~36% of the thickness of test sample.

(iv) Calculation of settlement is carried out assuming that the object layer is sandwiched between the drainage layers such as sand with high permeability. However, as the upper and lower layers of Layer 1 are estimated as clay with low permeability, the actual settlement shall be less than the calculated value.

Table 3.2.2 Result of Soil Test (Atterberg Limit) at BH1

BH No.

Layers Soil Name Depth

(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL

Direct Shear Test Triaxial

Compression Test c

(kg/cm2) φ

(deg) c (kg/cm2)

φ (deg)

BH.1 1 Fat Clay 4.5~5.5 92.5 1.46 2.65 96.90 35.40 0.9285 0.041 2.67 0.93 11.5 9.0~9.5 75.7 1.54 2.68 84.30 37.00 0.8182 0.08 4.88 0.123 11.8

2 Lean Clay 17.0~17.5 22.1 2.07 2.74 43.00 18.80 0.1364 0.4 14.53 3 Silty Clayey Sand 24.5~25.0 17.5 2.02 2.67 19.00 14.80 0.6429 0.092 30.15

Reference data obtained from HCMC Highway Project (PK7:embankment)


(m) W

(%)

Wet Density

γw(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL


Compression Test c

(kg/cm2) φ

(deg) c (kg/cm2)

φ (deg)

Layer 1 Fat Clay 0~2.91 87.06 1.46 2.61 85.60 38.50 1.031 0.057 3.37 0.09 20.89 Sub Layer Lean Clay 2.91~19.7 32 1.9 2.7 45.80 21.40 0.4344 0.2 11.26 0.13 0.36 Layer 3 Clayey Sand 19.7~75 16 2 2.7 26.00 15.40 0.0566 0.2 22.64 Source: JICA Study Team

Table 3.2.3 Result of Consolidation Test at BH1

Br. No. Depth

(m) Load (kg/cm2)

ΔP d0 d100 Δd

(cm) Cv (x10-3)

cm2/s Pc

(kg/cm2) ΔH

(cm) Hi

(cm) mv

mv*Hi *ΔP

Settle- ment from to

BH.1 Sample: H=2.0cm

4.5~5.5 0 0.125 0.125 0.0082 0.0388 0.0306 0.598 0.37 0.043 1.957 0.1251 0.0306 0.125 0.25 0.125 0.0424 0.0833 0.0409 0.287 0.09 1.91 0.1713 0.0409

0.25 0.5 0.25 0.089 0.1836 0.0946 0.209 0.2025 1.7975 0.2105 0.0946 0.5 1 0.5 0.2025 0.3722 0.1697 0.183 0.404 1.596 0.2127 0.1697

1 2 1 0.4065 0.5546 0.1481 0.169 0.582 1.418 0.1044 0.1481 2 4 2 0.5845 0.7137 0.1292 0.156 0.731 1.269 0.0509 0.1292 4 8 4 0.7305 0.8424 0.1119 0.142 0.8565 1.1435 0.0245 0.1119 0.725

9.0~10.0 0 0.125 0.125 0.009 0.0309 0.0219 0.527 0.66 0.0343 1.9657 0.0891 0.0219 0.125 0.25 0.125 0.0325 0.0626 0.0301 0.255 0.068 1.932 0.1246 0.0301

0.25 0.5 0.25 0.067 0.1188 0.0518 0.186 0.132 1.868 0.1109 0.0518 0.5 1 0.5 0.1365 0.2276 0.0911 0.138 0.2505 1.7495 0.1041 0.0911

1 2 1 0.251 0.3898 0.1388 0.118 0.417 1.583 0.0877 0.1388 2 4 2 0.42 0.5586 0.1386 0.105 0.58 1.42 0.0488 0.1386 4 8 4 0.579 0.6964 0.1174 0.092 0.717 1.283 0.0229 0.1174 0.5897



3-12

(d) Comment for Railway Construction of B.H.1

3.29 Structure of Thu Thiem Station is planned as the PC girders with pile foundation. Because the bottom of bored hole did not reach the strata with N value more than 50, pile length should be determined in the detail design stage. For reference, as the result of boring log in HCMC Highway Project, the depth of foundation strata is around G.L.-70m or deeper.

3.30 Water drainage method such as paper drain, deep well, etc., shall be required against the ground settlement. Soil improvement work should be taken in consideration to avoid uneven settlement of ground surface.


3.31 Boring No.2 locates at the depot area where embankment is planned. Some numbers of small rivers are flowing in this area. Water levels of those rivers are nearly same as the ground level. Drainage of ground water by the plastic drain (Figure 3.2.3) and the consolidation acceleration method by dead load are used to avoid settlement of ground surface and structures. The purpose of Boring No. 2 is to check the geology and soil conditions for the railway structures.


Figure 3.2.3 Boring Location in HCMC Depot Location


3.32 This area locates near to the branch of Dong Nai River and several numbers of canals are constructed to avoid the flood of Dong Nai River. Ground water level exists at shallow depth as G.L.-1.0.

3.33 Ground surface is covered by sand, silt and clay layers with some organic traces while the sand, silt clay layers of Lower to Middle Holocene are deposited underneath. Thickness of each layers are 10 m, 2 m to 10 m, respectively.


3.34 Ground water level is recorded as G.L. -1.0 m from the ground surface.

3.35 Boring log is described as follows;

(i) From ground surface to G.L.-1.3 m is covered by filling soil.

(ii) Fat clay with N≈0 containing organic substance deposited from G.L.-1.3 m to G.L.-14.5 m. Trace of organic substance is observed until G.L. -14.5 m.

(iii) Alteration of clay and fine sand deposited from G.L.-14.5~-18.0 m is with N value of 9 to 23 and dense. This layer may be lens as the other B.H. drilled for the HCMC Highway Project has no description about this layer.



3-13 3-13

(iv) G.L.-18.0 m to G.L. -40 m is mainly composed of medium dense silty sand with N>10 while weak clay layer with N<10 exists from G.L.-28.5 m to G.L.-34.3 m.

(v) Bore Hole Log referenced from the result of HCMC Highway inspection Boring shows that the weak clay and silt layer with N<10 distributed until G.L.-30 m and the clayey sand with N>50 which has sufficient strength for the foundation appears at the G.L. more than 40 m.


3.36 Table 3.2.4 shows the summary of Atterberg Limit (LL, PL etc.) obtained from B.H.2 and boring data of the HCMC Highway. Table 3.2.5 shows the result of consolidation test in B.H.2.

3.37 Result of soil investigation is summarized below.

(i) Liquidity Index (iL) of the fat clay at depth G.L.-10.0~-10.5 m and sandy lean clay (G.L.-16.6 ~17.0 m) show high value of iL=0.911, iL=0.818, respectively. These values mean that those layers are classified as the sensitive clay that may cause the low trafficability.

(ii) Layer 1 of HCMC Highway Project shows high water content and iL=0.976 which is classified as the sensitive clay. A plastic water drainage system is applied to prevent ground settlement.

(iii) Settlement of fat clay calculated from the consolidation test is 16%~29% of the thickness of test sample.

(iv) Calculation of settlement is carried out assuming that the object layer is sandwiched between the drainage layers such as sand with high permeability.

(v) Clay layer from G.L.-28.5~34.3 m shall not be consolidated as it firm and the N value is ranging from 5 to 10.


BH No.


(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL


Compression Test c

(kg/cm2) φ

(deg) c (kg/cm2)

φ (deg)

BH.2 1 Fat Clay 10.0~10.5 75.6 1.52 2.68 79.60 34.70 0.9109 0.105 12.23 2 Sandy Lean Clay 16.6~17.0 23.6 2.03 2.72 25.60 14.60 0.8182 0.177 8.21 3 Silty Sand 24.5~24.95 19.4 2.65

4 Elastic Sand 30.0~30.5 42.7 1.78 2.72 57.80 31.00 0.4366 0.208 8.3 0.214 13.55

Reference data obtained from HCMC Highway Project (PK2:Dong Nai area)


(m) W

(%)

Wet Density

γw(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL


Compression Test

c (kg/cm2)

φ (deg) c (kg/cm2)

φ (deg)

Layer 1 Elastic Silt 0.0~10 91.3 1.45 2.62 92.40 47.40 0.9756 0.062 3.58 0.083 25.35 Layer 2 Fat Clay 10~30 39.4 1.8 2.7 63.30 30.30 0.2758 0.276 10.46 1.236 Layer 3 Clayey Sand 30~40 15.88 2.07 2.66 24.60 14.40 0.1451 0.428 24.65 Layer 4 Lean Clay with Sand >40 15.7 2.11 2.69 48.10 20.10 -0.157 1.059 17.93 Source: JICA Study Team


3-14


Br. No. Depth

(m) Load (kg/cm2)

ΔP d0 d100 Δd

(cm) Cv (x10-3)

cm2/s Pc

(kg/cm2) ΔH

(cm) Hi

(cm) mv

mv*Hi *ΔP

Settle- Ment from to

BH.2 Sample: H=2.0cm

10.0~10.5 0 0.125 0.125 0.003 0.04 0.037 0.358 0.72 0.046 1.954 0.1515 0.037 0.125 0.25 0.125 0.0474 0.0738 0.0264 0.331 0.0775 1.9225 0.1099 0.0264

0.25 0.5 0.25 0.088 0.1302 0.0422 0.299 0.1375 1.8625 0.0906 0.0422 0.5 1 0.5 0.139 0.2261 0.0871 0.165 0.2485 1.7515 0.0995 0.0871

1 2 1 0.2545 0.3771 0.1226 0.135 0.4065 1.5935 0.0769 0.1226 2 4 2 0.4065 0.5484 0.1419 0.12 0.573 1.427 0.0497 0.1419 4 8 4 0.5707 0.6971 0.1264 0.018 0.7145 1.2855 0.0246 0.1264 0.584

30.0~30.5 0 0.25 0.25 0.0046 0.0351 0.0305 0.339 2.61 0.0405 1.9595 0.0623 0.0305 0.25 0.5 0.25 0.0396 0.0578 0.0182 0.297 0.061 1.939 0.0375 0.0182 0.5 1 0.5 0.0611 0.0869 0.0258 0.278 0.091 1.909 0.0270 0.0258

1 2 1 0.0895 0.1263 0.0368 0.296 0.1325 1.8675 0.0197 0.0368 2 4 2 0.131 0.1747 0.0437 0.355 0.1835 1.8165 0.0120 0.0437 4 8 4 0.1878 0.2542 0.0664 0.273 0.2655 1.7345 0.0096 0.0664 8 16 8 0.2625 0.3621 0.0996 0.255 0.3755 1.6245 0.0077 0.0996 0.321


(d) Comment for Railway Construction

3.38 HSR structure in this depot area is planned as embankment. As result of the consolidation test of fat clay depositing from G.L.-1.3 m to G.L.-14.5 m of which sandy layer is lying beneath is anticipated to be sunk around 29% of the thickness of layers.

3.39 Water drainage method such as paper drain, deep well shall be required against the ground settlement. Soil improvement work should be taken in consideration to avoid uneven settlement of ground surface.

(3) Boring 2A (B.H.2A)

3.40 Boring 2A was drilled at the Long Thanh Station where Long Thanh International Airport (LTIA) has been planned. HSR route is passing through this area in the direction of South West to North East.


Figure 3.2.4 Boring Location in LTIA Area

3.41 Structure of Long Thanh Station is planned as shallow trench type and the purpose of Boring 2A is to confirm the depth of foundation.

(a) Regional Geology of B.H.2A

3.42 Topography in this area is characterized widely spreading Basalt Plateau. Ground surface is moderately inclined towards to Dong Nai River. Sand, silt and



3-15 3-15

clay of Upper Pleistocene is spreading on the ground surface and Basalt Lava erupted in Neogene Period lies beneath of them. Foundation rock, Basalt, in this area shall be found in shallow depth.

(b) Result of Inspection Boring of B.H.2A

3.43 Rubber plantation is widely developed in this area and groundwater level is found at G.L.-2.5 m.

3.44 Firm and stiff red brown clay with 10<N<20 is deposited from ground surface to G.L.-16.2m and very stiff sandy clay layer (N≈20) lies from G.L.-16.2 m to G.L.-22.0 m. Fine grained and medium dense silty sand with N=20~35 appears from G.L.-22.0 m to G.L.-30.5 m.

3.45 Boring data oh HCMC Highway Project drilled Dong Nai River side of National Highway QL55 shows that the soft soil of N<10 is deposited at G.L. -30 m. This B.H. data means that B.H. No.2A area is better than the Dong Nai area.

(c) Result of Soil Tests of B.H.2A

3.46 As the type of soil in Long Thanh International Airport area is well-known in the Long Thanh–Dau Giay express highway, soil tests were not carried out in this bored hole.

3.47 Maximum value of Liquid index of clay and silty sand obtained from the result of soil test of the highway project data shows low value as iL=0.44 and those soils have no characteristics of sensitive clay.


3.48 Long Thanh Station should be considered with the detail design of LTIA. Herein, it is assumed that the open cut excavation and pile foundation are major construction works, the depth of base strata shall appear in shallow depth.


3.49 Boring No.3 was planned in the white sand area near Phan Thiet. Fruit farm is widely developed in this area and surface soil is mainly composed of white sandy soil characterized some traces of gully erosion (Figure 3.2.5). HSR structures in this area are planned as cut and embankment. Boring No.3 is carried out to inspect the physical and mechanical properties of white sand soil.


Figure 3.2.5 Boring Location in White Sand Area near Phan Thiet


3-16


3.50 Ground surface is mainly covered with white sand and dune sand forms sand bank along the seashore.

3.51 Base rocks of this area are composed of the sedimentary rock such as sandstone, siltstone, shale of Jurassic Period and rhyolite group of Cretaceous Period.

(b) Result of Inspection B.H.3

3.52 Result of Boring No.3 is described as follows;

(i) Location of Boring No.3 is near the river and ground water level found in a shallow depth as G.L.-0.7 m. As the thickness of surface soil is 0.7m, ground water level exists at the bottom of surface soil.

(ii) Light gray and red brown colored lean clay deposits from G.L.-0.7 m to G.L.-5.1 m and stiff yellow gray colored sandy lean clay lies from G.L.-5.1 m to 8.2 m.

(iii) From G.L.-8.2 m to G.L.-20 m is composed of siltstone and sand stone. Upper and lower parts of siltstone/sandstone are moderately weathered, fractured, respectively.

(iv) Siltstone and sandstone is considered as the La Nga formation of Jurassic Period. TCR & R.Q.D from G.L.-10 m to G.L.-20 m show high value of TCR=70 to 80%, RAD=50 to 65%.


3.53 Summary of Atterberg Limit (LL, PL etc.) in B.H.3 is shown in Table 3.2.6.

(i) Grain size of lean clay contains more than 80% fine particles and content of fine materials is less in the sandy lean clay. Coefficient of uniformity, UC=(D60/D10), could not be calculated as the quantity of fine particles exceeds 10%.

(ii) Uniaxial strength of siltstone and sandstone at the depth of G.L. 16.8 m to G.L.-17.0 m shows �c=400~500 kg/cm2 and weathered ratio shall be low value.

(iii) Stress-Strain curve of the rock shows elastic deformation but some non-leaner behavior is shown near to the failure. Shape of rupture of rock is almost agreeable but photo of sample after test shows a tendency of restrain of the end plane.


BH No.

Soil Name Depth

(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Porosity (%)

Void Ratio

Coef. of Uniformity

Direct Shear Test c

(kg/cm2) φ

(deg)

BH.3 Lean Clay 2.0~2.5 20.3 2.08 2.76 37 0.596 nul 0.422 17.31 20.4 2.00 2.75 40 0.656 nul

Sandy Lean Clay 5.0~5.5 18.7 2.11 2.71 34 0.525 nul 0.142 17.14

18.6 2.12 2.8 34 0.51 nul




3-17 3-17


3.54 Very stiff lean clay with N>10 is depositing in this area and this type of soil has enough bearing capacity for embankment. However, cut slope should be taken care of the gully erosion due to heavy rain.


3.55 Boring No.4 is located at the new Phan Thiet existing railway station which was recently constructed. Phan Thiet HSR Station is planned as the elevated platform supported by the PC girders with pile foundation. Boring No.4 is drilled to collect soil data available for the design of structures in Phan Thiet Station.


Figure 3.2.6 Boring Location at Phan Thiet Existing Line New Station

(a) Regional Geology of B.H. 4

3.56 Sand and clay layers of Middle Holocene estimated as the river deposit of Ca Ty River is widely distributed and forming alluvial fan. Stiffness of surface soil is checked during field survey.

(b) Result of Inspection Boring of B.H.4


(i) Lean clay with N=4~5 deposited from G.L. to G.L.-3 m.

(ii) Medium dense clayey sand lies from G.L.-3 m to G.L.-5 m while stiff clay, sandy lean clay and lean clay lie from G.L.-50 m to 12.0 m. N values of those layers vary from 15 to 21.

(iii) Dense silty clayey sand is distributed from G.L.-12.0 m to -15.0 m and N values are higher than 50.

(c) Result of Soil Tests B.H.4

3.58 Purpose of soil test is to grasp soil conditions around Phan Thiet Station area. Atterberg Limit test and consolidation test have been carried out. The results of soil tests are shown in Table 3.2.7 and Table 3.2.8.

(i) Wet density of samples are higher than 2.0. However, water content of those samples are less than 20% and porosity is distributed from 35% to 38%. Those values suggest that those soils are dense and stiff.

(ii) Result of consolidation test executed at the depth of 2.0 m shows low


3-18

settlement value and ground settlement shall not be taken in place.

(iii) Pile foundation shall be fixed in the silty clay which lies from G.L.-12.0 m to -15.0 m.


BH No. Soil Name

Depth (m)

W (%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Porosity (%)

Void Ratio

Coef. of Uniformity

Direct Shear Test c

(kg/cm2) φ

(deg)

BH.4 Lean Clay with sand 2.0~2.5 20.4 2.05 2.74 38 0.609 nul 0.372 15.71 2.0~2.5 19.8 2.07 2.75 37 0.592 nul

Sandy Lean Clay 8.0~8.5 17.5 2.10 2.7 34 0.511 nul 0.224 18.12 Silty Clayey Sand 12.0~12.5 18.9 2.07 2.67 35 0.534 nul



Br. No. Depth

(m) Load (kg/cm2)

ΔP d0 d100 Δd

(cm) Cv (x10-3)

cm2/s Pc

(kg/cm2) ΔH

(cm) Hi

(cm) mv

mv*Hi *ΔP

Settle- ment from to

Br.4 Sample.H=2.0cm

2.0~2.5

0 0.25 0.25 0.0218 0.0312 0.0094 0.812 1.43 0.033 1.967 0.0191 0.0094

0.25 0.5 0.25 0.0365 0.0458 0.0093 0.887

0.0475 1.9525 0.0191 0.0093

0.5 1 0.5 0.0542 0.0661 0.0119 0.8

0.0675 1.9325 0.0123 0.0119

1 2 1 0.0765 0.0908 0.0143 0.89

0.0925 1.9075 0.0075 0.0143

2 4 2 0.1057 0.1227 0.017 0.637

0.1255 1.8745 0.0045 0.017

4 8 4 0.1423 0.163 0.0207 0.757

0.166 1.834 0.0028 0.0207

8 16 8 0.1806 0.2138 0.0332 0.963

0.217 1.783 0.0023 0.0332 0.1158 Source: JICA Study Team


3.59 Foundation of Phan Thiet Station exists in comparatively shallow depth as G.L.-12 m.

(6) Boring 4A

3.60 Boring No.4A is located around 1 km upper streamside of the bridge where National Highway No.1 is crossing the Ca Ty River before the HSR gets in the Phan Thiet station.


Figure 3.2.7 Boring Location on the Bank of Ca Ty River

(a) Regional Geology of B.H.4A

3.61 Topography of the Boring No. 4A point is the slip off slope of Ca Ty River



3-19 3-19

and the alluvial deposit covers ground surface. According to the geological map in this area, ground surface is covered by the Upper Holocene deposit such as sand, silt and clay of 4 m thick and quartz sand of Upper Pleistocene lies beneath of the former layer.

(b) Result of Inspection Boring B.H.4A


(i) Thickness of surface soil is 0.5m and ground water level recorded at the depth of 5m from G.L.

(ii) Medium to coarse-grained loose sand with N<10 lies from G.L.-0.5 m to G.L.-6.0 m and stiff sandy clay deposits from G.L.-5.0 m to 15.0 m. N value of sandy clay shows low value as less than 15.

(c) Comment for Railway Construction

3.63 From the result of site survey, ground surface of the riverbank is covered by the sand and gravel conveyed by the Ca Ty River (Figure 3.2.8). Depth of strata for the foundation of National Highway seems shallow though B.H.4A did not encounter high N value.


Figure 3.2.8 Crossing Point Location of HSR and Ca Ty River

(7) Boring No.5, 5A,5B

3.64 Huge desert hill formed by the costal terrace is spreading from Phan Thiet to Phan Ri Cua town (Tuy Phong) and gully erosion of the surface of dune area is observed elsewhere (Figure 3.2.9). Two routes of HSR are investigated in this area. One is passing through the desert area nearly straight line to connect directly Phan Thiet and Tuy Phong stations. The other is to detour to the north near to the existing railway and the National Highway No 1 to avoid construction works in the desert area.

3.65 Preliminary, B.H. No.5 was planned for the purpose to investigate soil properties of sand dune in north side. However, as meeting with PC of Binh Thuan Province, there was a strong request to carry out more studies for the straight route running through the desert area. Therefore JICA Study Team has carried out the investigation at B.H.No.5A & 5B to study more about the geology conditions of the desert area between Phan Thiet and Tuy Phong station.


3-20

No. 5 No. 5A

No. 5B


Figure 3.2.9 Boring Location of No. 5, 5A, 5B

(a) Regional Geology of Desert Area

3.66 Red sand of unclassified Quaternary deposit (vQ) is distributed on the costal hill and forming the desert area. Elevation of desert area is higher than 100m and is highly dissected by many small valleys.

3.67 Booklet of “Geology and Mineral Resources” issued by the Department of Geology and Minerals of Viet Nam in 1998 says that the topography of the desert area is wind origin and geometry of grand surface shall change every year. Dune sand in this area is causing the traffic disturbance. Marine origin with brown and gray colored sand (mQIIpth) is depositing beneath the sand dune. Thickness of this layer is estimated 70 m to 80 m.

3.68 Red colored sand accompany with thin white colored sand layer of Upper Pleistocene to Holocene (mQIIpth) is depositing near seashore and riverbank.

3.69 Several numbers of inselbergs of rhyolite are buried in the sand and are forming sand summit. Rhyolite in Cretaceous Period is distributed near National Highway No.1 and the seashore. Rhyolite mountain is utilized as the quarry site (Figure 3.2.10).


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

3-50

Tab

le 3.2.21 So

il Testin

g R

esults in

So

uth

Sectio

n (H

CM

C–N

ha T

rang

Sectio

n) (2/4)

Source: JIC

A Study Team


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

3-51

3-51

Tab

le 3.2.22 So

il Testin

g R

esults in

So

uth

Sectio

n (H

CM

C–N

ha T

rang

Sectio

n) (3/4)

Source: JIC

A Study Team


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

3-52

Tab

le 3.2.23 So

il Testin

g R

esults in

So

uth

Sectio

n (H

CM

C–N

ha T

rang

Sectio

n) (4/4)

Source: JIC

A Study Team



3-21 3-21


Figure 3.2.10 Rhyolite Mountain Utilized as the Quarry Site near NH1A

(b) Result of Inspection Boring B.H.5, 5A, 5B

3.70 Three borings are drilled in this area and the locations are shown in Figure 3.2.11.

(i) Silty sand is distributed from ground surface to G.L.-30 mto G.L.-35 m in all borings.

(ii) Distribution of N values of those borings have nearly same tendency that the sufficient N value for the foundation of structures (N>50) is recorded from G.L.-16 m to -20 m.

(iii) Ground water level of B.H.No.5 is recorded at G.L.-3.5 m. Other boreholes have no records. However, soil test sample of B.H.No.5A and 5B are wet and the results of natural moisture content tests show around 20%. Drilling water may remain in those samples.

Phan Thiet Tuy PhongvQ sand area

Location of geological investigation carried out by JST

Alt-1 Alt-3Alt-2

5A5B

5


Figure 3.2.11 Location of BH5, 5A, 5B and the Alternative Routes

(c) Result of Soil Tests B.H.5, 5A, 5B

3.71 Results of soil tests of B.H.5, 5A, 5B are shown in Table 3.2.9. Tests in those borings are focused on the grain size distribution.

(i) Coefficient of Uniformity (Uc) of B.H. 5 and 5B at the depth of G.L.-2.0~2.5 m show low value and grain size of fine to medium sand are predominant. B.H.5B of same depth is more clayey and shows high Uc value.

(ii) Grain size distribution of B.H. No.5 until G.L.-15 m indicates low Uc values and this values is estimated as an unstable value against to the gully erosion.

(iii) Porosity and void ratio of sand layers in B.H.5A and 5B are nearly same value


3-22

until G.L.-15m though the overburden thickness is increasing. This suggests that those layers are wind origin.

(iv) Average values of internal friction are 30 degree (φ=3”) and these are same

as standard sand.

(v) As described in the former section, ground water levels of B.H.No.5A and 5B were not recorded but the moisture contents of test samples indicate higher value than B.H.5. As the result, the cohesion and internal friction of B.H. 5A and 5B is thought to be suspicious and should be considered as the apparent value.

Table 3.2.9 Result of Soil Test (Atterberg Limit) at BH5, 5A, 5B

BH No.

Soil Name Depth

(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Porosity (%)

Void Ratio

Coef. of Uniformity

Direct Shear Test c

(kg/cm2) φ

(deg)

BH.5 Silty Sand 2.0~2.5 13.6 1.71 2.69 44 0.787 5.70 0.037 32.78 13.8 1.68 2.68 45 0.815 5.00

8.0~8.5 10.6 1.98 2.69 33 0.503 6.20 0.063 32.88

9.7 2.00 2.67 32 0.464 7.00

15.0~15.5

10.3 1.97 2.67 33 0.495 8.40 0.013 28.51 10.7 1.96 2.68 34 0.514 6.30

25.0~25.5 12.7 2.04 2.67 32 0.475 49.50 0.074 31.83

Lean Clay with Sand 38.0~38.5 15.8 2.18 2.7 30 0.434 nul 1.026 21.8 BH.5A Silty Sand,

Silty Clayey Sand 2.0~2.5 17.2 1.94 2.67 38 0.613 142.80 0.037 30.35

17.7 2.01 2.68 36 0.569 88.20 0.033 29.43 8.0~8.5 15.5 1.87 2.67 39 0.649 9.30 0.029 31.51

15.6 1.78 2.67 42 0.734 7.60 0.025 30.8 15.0~15.5 18.9 1.96 2.68 38 0.626 nul 0.031 29.65

19.0 2.00 2.67 37 0.589 nul

25.0~25.5 18.0

2.69

135.80

BH.5B Silty Sand 2.0~2.5 13.9 1.78 2.68 42 0.715 5.90 0.018 38.63 12.7 1.87 2.68 38 0.615 8.70 0.019 29.48

8.0~8.5 19.9 2.03 2.68 37 0.583 108.60 0.036 31.98 21.5 2.01 2.67 38 0.614 43.80 0.031 29.5

15.0~15.5 19.1 1.93 2.68 40 0.654 8.90 0.027 31.5 18.0 2.05 2.67 35 0.537 25.60

25.0~25.5 18.2 2.08 2.68 34 0.523 7.30 0.022 32.08



3.72 Cut and embankment are planned for the HSR Railway structures.

3.73 Sand layers deposited in this area have sufficient bearing capacity, but it shall easily collapse due to earthwork, especially in case of slope cut. Slope protection work and ground improvement shall be requires to stabilize the cut slope.

3.74 Wind blowing near seashore will be stronger than the N.H.1 side. Many maintenance problems such as abrasion of rail, burial of railway, and so on, shall happen when the HSR route was planned to pass through the desert area.

3.75 It is recommended that the HSR route should planned near to the N.H.1.



3-23 3-23


3.76 Tuy Phong Station is planned by the embankment. White sand area where many wind power stations located is widely spread along to seashore from Tuy Phong to Chi Cong (Figure 3.2.12). Boring No.6 was carried out to investigate physical properties of white sand in this area.

4.2 Boring location near Tuy Phong Station Location White Sand Area from Tuy Phong to Chi Cong


Figure 3.2.12 Boring Location No 6 and White Sand Area near Tuy Phong


3.1 Three meter to fifteen meter thick quartz sand and calcareous sand layer of Upper Pleistocene is mainly distributed in this area while sand, silt and clay layers are deposited on the alluvial fan of Luy River.



(i) Light gray colored sand and silty sand is deposited from G.L. to G.L.-11.5 m.

(ii) Upper part from G.L. to G.L.-5 m is composed of medium dense sand with N<20. Fine grained silty sand with 40>N>29 lying from G.L.-5m to G.L.-11.5 m.

(iii) Stiff to hard silty clayey sand is deposited firm G.L.-15.5 m to G.L.-15.0 m. N value of this layer changes in the range of 29 to 36.

(iv) Groundwater is recorded at G.L.-3m.


3.3 Soil investigation was focused to confirm the stability of white sand. Results of soil tests are shown in Table 3.2.10.

(i) Coefficient of uniformity (Uc) of sand with silt layers from G.L. to G.L.-5 m show low value as Uc=4.3 to 5.8.

(ii) Silty sand sample at the depth of G.L.-9.0 m to 9.5 m contains fine particles and Uc calculation is out of range.

(iii) Result of direct shear test indicates that the internal friction angle of sandy soil

is around 30 degree (φ=30 ﾟ) as same as standard sand.


3-24


3.4 Boring data drilled near Tuy Phong Station shows high N value to satisfy the required strength of foundation.

3.5 Light gray sand deposited from G.L. to G.L.-5.5 m shows low Uc value. Earthwork in this area should be taken care to the gully erosion and slope collapse.


BH No.

Soil Name Depth

(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Porosity (%)

Void Ratio

Coef. of Uniformity

Direct Shear Test c

(kg/cm2) φ

(deg)

BH.6 Poorly Graded Sand with silt, silty clayey sand

2.0~2.5 11.9 2.00 2.68 33 0.499 5.80 0.012 24.81 13.1 1.98 2.67 34 0.525 4.30

5.0~5.5 19.8 1.98 2.68 38 0.622 4.30 0.045 30.03

18.2 1.98 2.67 37 0.594 5.00

9.0~9.5 15.1 2.10 2.68 32 0.469 nul 0.109 29.58 14.9 2.08 2.68 32 0.48 nul

Sandy lean Clay 11.5~12.0 14.1 2.13 2.7 31 0.446 nul 0.233 27.05


(9) Boring 7A (B.H.7A)

3.6 The purpose of this boring is to collect the data available for the decision of the location of south portal and length of the tunnel.


Figure 3.2.13 Boring Location for South Portal of Tunnel in Ca Na

(a) Regional Geology B.H.7A

3.7 This area is characterized as high mountains plunging to the Ca Na beach. Geology of mountain area is composed of granite group of Jurassic Period and granitic intrusive in Cretaceous Period.

3.8 “Cubic Joint Open Crack” developed on the surface of granite outcrops and rock mass is separated to be cubic shape as shown in Figure 3.2.13.

(b) Result of Inspection Boring B.H.7A

(i) Depth of bored hole is 20 m and weathered granite is observed in the whole length.

(ii) According to the HSR Tunnel Rock Classification, this granite shall be classified as the “Completely Weathered to Decomposed Granite”.



3-25 3-25

(iii) Large grain clayey sand of φ0.1~2.0 mm grain size which is deemed to be

the “Decomposed Granite” is predominating from G.L. to G.L.-2 m. Highly to completely weathered granite lies beneath of them.

(iv) Ground water was not recorded in the borehole log, but permeability of weathered granite is anticipated to be a low value.


3.9 In the tunnel portal design, the talus deposit, thickness of weathered zone, small currents, etc should be considered.

3.10 Thick weathered zone is predicted from the result of boring inspection. Sometimes, weathered zone at the portal may continue more than 100m. In such case, location of tunnel portal should be shifted.

3.11 More detail inspections should be carried out to find the appropriate location of the tunnel portal.

(10) Boring 7 (B.H.7)

3.12 Salt farm is spreading from Ca Na to the south of Thap Cham City. Not many plantations are visible in this area. Loose sand is distributed in the salt farm and many troubles were observed during site survey. For example, abutments of concrete bank protection of small rivers were found with flow out, boiling of water from river bed (Fugure 3.2.14) and so on.

3.13 This phenomenon suggests that the mountain behind of this area is reserving huge amount water. Submerged water flows out to the salt farm and causes the boiling water to occur.

3.14 Boring No.7 was drilled to inspect the geology of south portal and permeability of rock joints.

4.3 Boring Location for North Portal of Tunnel in Ca

Na Collapse of Abutment near Salt Farm in Ca Na Area


Figure 3.2.14 Boring Location No. 7 and Loose Sand in Salt Farm in Ca Na


3.1 Granite of Jurassic Period and granite intrusive in Cretaceous Period are distributed in the tunnel area. “Cubic Joint Open Crack” develops on the surface of granite outcrops and rock mass is separated to be cubic shape (Figure 3.2.14).


3-26


(i) Depth of bored hole is 20 m but underground water level was not recorded. Underground water level obtained from the result of electrical logging shows G.L.-3 m.

(ii) Talus deposit is observed from G.L.-1.0 m to G.L.-10.1 m and granite of Jurassic Period is deposited beneath of those strata.

(iii) Total Core Recovery (TCR) and Rock Quality Designation (R.Q.D.) indicate high values as shown in the following table.

Table 3.2.11 T.C.R. & R.Q.D. of Boring No.7

Depth (m) G.L. -m

Total Core Recovery T.C.R. (%)

Rock Quality Designation R.Q.D. (%)

10.1~10.5 90 80 10.5~12.8 100 95 12.8~15.5 95 95 15.5~17.8 98 95 17.8~20.0 100 97



(i) Grain size distribution of weathered granite contains less amount of fine material and most of all are composed of gravels.

(ii) Uniaxial strength of granite is estimated from 750 kg/cm2 to 1,200 kg/cm2 and stress-strain curve shows elastic behavior.

(iii) Stress-Strain curve of this test shows elastic deformation but some non-leaner behavior is shown near the failure.

(iv) Shape of rupture of rock is almost agreeable but figure of sample after test show a tendency of restrain of the end plane.

(d) Result of Electric Logging of B.H.7

3.2 Electric Logging is planned to make clear the following points.

(i) To inspect the cause of boiling water spring out from riverbed.

(ii) To make clear the drought area around the tunnel because many systematic joints of the granite are observed in this area.

3.3 Results of electric logging are described hereunder.

(i) Ground water level is G.L.-3.5 m and electric resistivity value of highly weathered granite laying around G.L.-3.5 m shows comparatively high value, while one of highly weathered granite from G.L.-3.5 m to G.L.-9 m is low. B.H. encountered slightly weathered granite from G.L.-10.1 m and electric resistivity value increased with B.H. depth.

(ii) ES curve and SP curve show smooth curve and have no irregularity. This curve means that the existence of open joints accompanied with water seepage in the slightly weathered granite will be limited.

(iii) As the result of electric logging, it is suggested that granite at the tunnel portal is intact rock and development of discontinuities shall be limited.



3-27 3-27

(e) Comment for Railway Construction

3.4 Tunnel route is mainly composed of fresh to slightly weathered granite and distribution of discontinuities (crack, joint, etc.) shall be limited only on the surface of the granite mass.

3.5 Weathered zone at the portal area is estimated around 10 m. Length of weathered zone at the portal area depends on the inclination of natural slope. Assuming that the inclination of slope of the mountain was 30 degree, weathered zone at the portal is estimated to be more than 17 m.

3.6 Ground water is recorded in the highly weathered granite. This suggests that the amount of water seepage in the fresh granite shall be less than the forecasted by the field survey. However, underground water shall flow along to the cracks and open joints of the rock and detail inspection is required for assessment of drought caused by the tunnel construction.


3.7 Thap Cham Station is planned by the PC girder elevated structure and parallel construction with the existing railway station. Boring No.8 is planned to inspect geology and depth of foundation layers.


Figure 3.2.15 Boring Location in Thap Cham Station Location


3.8 Geologically, Thap Cham Station locates near the border of Alluvial Deposit (sand, silt, etc.) and rhyolite, dacite of Nha Trang Formation in Cretaceous Period.

3.9 Monument of Cham tower locating west side of the Thap Cham Station is constructed on the hill of Nha Trang Formation.


(i) Sandy lean clay of alluvial sediment is deposited from G.L.-0.4 m to G.L.-5.8m and thickness of topsoil is 0.4 m. Sandy lean clay layer is fairly stiff and N value is from 6 to 9.

(ii) Highly Weathered Andesite and Slightly Weathered Andesite is lying from G.L.-5.8 m to G.L.-6.5 m, G.L.-6.5 m to G.L.-9.5 m, respectively.


3-28

(iii) TCR and R.Q.D. of slightly weathered granite from G.L.-5.8m to G.L.-6.5 m are TCR=80%, RQD=35% and one from G.L.-6.5 m to G.L.-9.5 m shows high value as TCR=90~100%, RQD=70~95%.


3.10 Results of soil test are shown in Table 3.2.12.

(i) Grain size distribution of sandy clay from G.L.-2.0~-2.5 m shows 60% clay content but content of sand is 40% and this is classified as sandy clay. Strength of sandy clay tested by the tri-axial compression apparatus indicates qu=1.6 kg/cm2 and classified as stiff clay.

(ii) Uniaxial compressive strength of andesite is distributed in the range of c = 740~1500 kg/cm2 and classified as fresh rock.


BH No.

Soil Name Depth

(m) W

(%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Porosity (%)

Void Ratio

Coef. of Uniformity

Direct Shear Test c

(kg/cm2) φ

(deg)

BH8 Sandy Lean Clay 2.0~2.5 15.4 2.10 2.7 33 0.487 nul 0.457 16.73 Source: JICA Study Team

(d) Comment for Railway Construction B.H.8

3.11 Foundation layer of fresh andesite is lying from G.L.-6 m and has sufficient strength for the foundation of the railway structures.

(12) Boring No.9

3.12 Existing Nha Trang Station is connected to the main railway line by the side track and HSR Station is planned on the west side of the exiting Nha Trang station. Structure of HSR station is planned as island platform of elevated structure.

3.13 This area is the flood area of Cai River and ground surface is covered by soft soil. B.H. No.9 is planned to inspect geology of the station area.


Figure 3.2.16 Boring Location in Nha Trang Station Location


3.14 Nha Trang City locates at the river mouth of the Cai River. Topography around this area is characterized as alluvial fun of Cai River and sandbar at the seashore. Some trace of lagoon is observed at the toe of southern mountain



3-29 3-29

(Figure 3.1.5).


3.15 Borehole log shows as follows;

(i) G.L. to G.L.-1.8 m: Filling soil, firm, ground water level is at G.L.-3.8m.

(ii) G.L.-1.8 to-14.3 m: Lean clay and fat clay, N≈0

(iii) G.L.-14.3 to -21.2 m: Alteration of sandy clay and fine sand, 0<N<5

(iv) G.L.-21.1~-25.0 m: Silty Sand, 10<N<20.

(v) G.L.-25.0~-31.3 m: Sandy Lean Clay, N≈5 to 15.

(vi) From G.L.-31.3 m: Highly weathered rhyolite, TCR=5~30%, RQD=0~10%.

3.16 High weathered granite has enough strength of the pile foundation.


3.17 Grain size distribution, the result of Atterberg limit test and consolidation test are shown in Table 3.2.13 and Table 3.2.14.

(i) Average of Liquid Index value of clay layer lying from G.L.-1.8~14.3m is iL=0.88 and classified as sensitive clay. However, iL values decrease with the sampling depth as iL=0.98 (-2.0~-2.5 m), 0.89 (-5.0~5.5 m), 0.81 (10.0~10.5 m).

(ii) iL of silty sand at the depth of G.L.-22.5~-22.95 m shows iL=1.21 and this value is same as quick clay. However, as percentage of fine sand is higher than silt and clay, silty sand shall not be classified as the quick clay.

(iii) Result of consolidation test of lean clay from G.L.-2.0~-2.5 m shows 16% of the thickness of strata.


BH No. Layers Soil Name

Depth (m)

W (%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL

Direct Shear Test Unconfined

Compression Test

c (kg/cm2)

φ (deg)

qu (kg/cm2)

strain (%)

BH.9 1a Clay with Sand 2.0~2.5 42.1 1.7 2.69 42.50 23.90 0.9785 0.069 6.85 0.24 15 5.0~5.5 44.1 1.76 2.68 46.40 26.00 0.8873 0.062 5.97 0.3 15

10.0~10.5 50.1 1.69 2.7 55.40 26.80 0.8147 0.107 7.03 1b Sandy lean Clay 15.0~15.45 37.6 2.72 34.90 22.20 1.2126 3 Sandy lean Clay 27.0~27.45 23.9 2.73 33.90 16.90 0.4118



Br. No. Depth

(m) Load (kg/cm2)

ΔP d0 d100 Δd

(cm) Cv (x10-3)

cm2/s Pc

(kg/cm2) ΔH

(cm) Hi

(cm) mv

mv*Hi *ΔP

Settle- ment From to

BH.9 H=2.0cm

2.0~2.5 0 0.125 0.125 0.006 0.0417 0.0357 0.592 0.95 0.047 1.953 0.1462 0.0357

0.125 0.25 0.125 0.049 0.074 0.025 0.385

0.0795 1.9205 0.1041 0.025

0.25 0.5 0.25 0.0821 0.1167 0.0346 0.513

0.122 1.878 0.0737 0.0346

0.5 1 0.5 0.125 0.174 0.049 0.496

0.1825 1.8175 0.0539 0.049

1 2 1 0.1841 0.2334 0.0493 0.581

0.2435 1.7565 0.0281 0.0493

2 4 2 0.2425 0.3057 0.0632 0.816

0.315 1.685 0.0188 0.0632

4 8 4 0.3135 0.383 0.0695 1.099



3-30


3.18 Nha Trang Station of HSR is planned elevated structure with Island Platform.

3.19 Foundation strata of rhyolite in this area exist at the depth of G.L.-31.3 m and soft clay layer of N<10 is deposited above the rhyolite. Especially, N value of lean clay lying from G.L.-1.8 m to G.L.-21.2 m is nearly equal N≈0 and ground improvement work shall be required.

(13) Boring No.10

3.20 Nha Trang Depot Area is planned by the embankment foundation on the rice field along the National Highway No.1 and soft soil layer covers ground surface (Figure 3.2.17). Boring No.10 is carried out to confirm the physical properties of strata in this area.


Figure 3.2.17 Boring Location in HCMC Depot Location

(a) Result of Boring Inspection of B.H.10

3.21 Borehole log is described as follows;

(i) Thickness of filling soil is 0.4 m and the ground water level is same as the bottom of surface soil.

(ii) Fat clay and coarse-grained sand with N≈5 is deposited from G.L.-0.4~-2.4 m, G.L.-2.4~3.5 m, respectively.

(iii) Soft fat clay with N≈0 is lying from G.L.-3.5 m to G.L.-9.7m.

(iv) Clay with garbled thin layer estimated as the base layer of rice field is deposited until G.L.-10.2 m.

(v) Weathered rhyolite is distributed from G.L.-10.2m to G.L.-20 m. Contact zone of upper layer and rhyolite is completely weathered and fragile. Weathered rhyolite facies changes associated with the depth.

(vi) TCR and R.Q.D of rhyolite from G.L.-11 m to G.L.-17.5 m shows TCR=40~50% and R.Q.D.=0. Those values from G.L.-17.5 m to G.L.-20 m show TCR=80%n R.Q.D.=25~30%.



3-31 3-31

(b) Result of Soil Tests of B.H.10

3.22 Physical properties and result of consolidation are shown in Table 3.2.15 and Table 3.2.16.

(i) Liquid index of fat clay deposited from G.L.-2.0~-2.5m and G.L.-8.0~-8.5 m are iL≈0.6, iL≈0.84, respectively. Lower layer of fat clay is more sensitive than the upper one.

(ii) As result of consolidation test, settlement of fat clay layer with depth from G.L.-2.0~-2.5 m is calculated as 30.1% of the thickness of strata.

(iii) Uniaxial strength of rhyolite is widely distributed from �c≈260kg/cm2 to �c≈970 kg/cm2.


BH No.

Layers Soil Name Depth (m)

W (%)

Wet Density γw

(g/cm3)

Specific Gravity Gs

(g/cm3)

Liquid Limit LL

Plastic Limit PL

Liqiud Index

iL

Direct Shear Test

Unconfined Compression Test

c (kg/cm2)

φ (deg)

qu (kg/cm2)

strain (%)

BH. 10

Layer K Fat Clay Firm

2.0~2.5 43 1.75 2.72 55.70 24.90 0.5877 0.173 6.12 0.43 10 44.5 1.74 2.72 55.30 26.00 0.6314 0.34 9.5

Layer 1 Fat Clay Very Soft

8.0~8.5 61.4 1.62 2.69 67.50 32.10 0.8277 0.113 5.38 62.1 1.63 2.7 67.60 32.30 0.8442



Br. No. Depth

(m) load (kg/cm2)

ΔP d0 d100 Δd

(cm) Cv (x10-3)

cm2/s Pc

(kg/cm2) ΔH

(cm) Hi

(cm) mv

mv*Hi *ΔP

Settle- ment From to

BH.10 H= 2.0cm

2.0~2.5 0 0.25 0.25 0.0075 0.0271 0.0196 0.463 1.61 0.0305 1.9695 0.0398 0.0196

0.25 0.5 0.25 0.0314 0.0468 0.0154 0.341

0.049 1.951 0.0316 0.0154

0.5 1 0.5 0.0506 0.0742 0.0236 0.29

0.0785 1.9215 0.0246 0.0236

1 2 1 0.0789 0.1172 0.0383 0.314

0.124 1.876 0.0204 0.0383

2 4 2 0.1245 0.1754 0.0509 0.401

0.185 1.815 0.0140 0.0509

4 8 4 0.1867 0.2576 0.0709 0.343

0.274 1.726 0.0103 0.0709

8 16 8 0.2717 0.3543 0.0826 0.249



3.23 Results of soil test indicate that the weak clay is deposited at the depth of G.L.-3.5~9.7 m. N value and settlement of these strata are N≈0, S≈30%, respectively. These values mean that the ground improvement is required to prevent ground settlement.

3) Detail data of Boring investigation in South Section

3.24 Herein the boring logs, standard penetration test diagram for each boring location and the detail soil testing results are detail described.

3.25 In the field, soil is classified in accordance with N value of SPT as follows:


3-32

Table 3.2.17 Classification for Cohesive Soil

No SPT value (blows) Composition

1 0 – 4 Very soft to soft 2 4 – 8 Firm 3 8 - 15 Stiff 4 16 – 30 Very stiff 5 > 30 Hard


Table 3.2.18 Classification for Cohesionless Soil

No SPT value (blows) Structure

1 0–10 Loose 2 10– 30 Medium dense 3 30–50 Dense 4 >50 Very dense


3.26 Based on the laboratory results, Soil is classified in accordance with ASTM designation D2487. This soil classification System based on laboratory determination of particle-size characteristics, liquid limit, and plasticity index.

3.27 This classification system identifies three major soil divisions: coarse-grained soils, fine-grained soils, and highly organic soils. These three divisions are further subdivided into a total 15 basic soil groups, as shown in the following table.



3-33 3-33

Table 3.2.19 Basic Soil Groups Used in Boring Investigation

MAJOR DIVISIONS

GROUP SYMBOLS

TYPICAL NAMES

CLASSIFICATION CRITERIA

CO

ARSE

-GR

AIN

ED S

OIL

S M

OR

E TH

AN 5

0%

RET

AIN

ON

No.

200

SIE

VE G

RAV

ELS

50%

OR

MO

RE

OF

CO

ARSE

FR

ACTI

ON

RET

AIN

ED O

N N

o.4

SIEV

E

CLE

AN

GR

AVEL

S GW Well-graded gravels and gravel- sand mixtures, littled, little or no fines

CLA

SSIF

ICA

TIO

N O

N B

ASI

S O

F PE

RC

ENTA

GE

OF

FIN

ES

LES

S TH

AN 5

% P

ASS

No.

200

SEI

VE

GM

, GP,

SM

, SP

MO

RE

THAN

12%

PAS

S N

o. 2

00 S

EIVE

G

M, G

C, S

M, S

C

5%

TO

12%

PAS

S N

o. 2

00 S

EIVE

BO

RED

ERLI

NE

CLA

SSIF

ICAT

ION

REQ

UIR

ING

USE

O

F D

UAL

SYM

BOLS

Cu= D60/D10 Greater than 4 Cz= Between 1 and 3

GP Poorly-graded gravels and gravel- sand mixtures, little or no fines

Not meeting both criteria for GW

GR

AVEL

S W

ITH

FIN

ES GM

Silty gravels, gravel-sand-silt mixtures

Atterberg limits plot below "A" line or plasticity index less than 4

Atterberg limits plotting in hatched area are borderline classifications requiring use of dual symbols GC

Clayey gravels, gravel-sand-clay mixtures

Atterberg limits plot above "A" line or plasticity index less than 7

GR

AVEL

S 50

% O

R M

OR

E O

F C

OAR

SE F

RAC

TIO

N P

ASSE

D N

o.4

SIEV

E

CLE

AN

SAN

DS

SW Well-graded sand and gravelly- sand mixtures, littled, little or no fines

Cu= D60/D10 Greater than 6 Cz= Between 1 and 3

SP Poorly-graded sand and gravelly-

sand mixtures, littled, little or no fines Not meeting both criteria for SW

SAN

D

WIT

H F

INES

SM Silty sands, sand-silts mixrures

Atterberg limits plot below "A" line or plasticity index less than 4

Atterberg limits plotting in hatched area are borderline classifications requiring use of dual symbols SC

Clayey sands, sand-clay mixtures

Atterberg limits plot above "A" line or plasticity index less than 7

FIN

E-G

RAI

NED

SO

ILS

50%

O

R M

OR

E PA

SS N

o. 2

00 S

IEVE

SILT

S AN

D C

LAY

LIQ

UID

LIM

IT 5

0% O

R L

ESS

ML Inorganic silts, very fine sands, rock

flour, silty or clayey fine sands

CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clay, silty

clays, lean clays

OL Organic silts and organic silty clays of low plasticity

SILT

S AN

D C

LAY

LIQ

UID

LIM

IT G

REA

TER

TH

AN

50%

MH Inorganic silts, micaceous or diatoma-

ceous fine sand or silts, elastic silts

CH Inorganic clays of high plasticity.

fat clays

OH Organic clays of medium to high plasticity

HIGHLY ORGANIC SOILS PT

Peat, muck, and other highly organic soils

6010

230 )(

xDD

D

6010

230 )(

xDD

D


(1) Boring Logs and Standard Penetration Test Diagram

3.28 The boring logs and standard penetration test diagram for all boring locations are shown as follows.


3-34


Figure 3.2.18 Boring No 1



3-35 3-35




3-36


Figure 3.2.20 Boring No 2A



3-37 3-37




3-38





3-39 3-39




3-40





3-41 3-41




3-42


Figure 3.2.26 Boring No 5B



3-43 3-43




3-44





3-45 3-45




3-46





3-47 3-47




3-48



(2) Boring Logs and Standard Penetration Test Diagram

3.29 Summary of soil testing results are shown in the following tables.


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

3-49

3-49

Tab

le 3.2.20 So

il Testin

g R

esults in

So

uth

Sectio

n (H

CM

C–N

ha T

rang

Sectio

n) (1/4)

Source: JIC

A Study Team

Study for the Formulation of High Speed Railway Projects on Hanoi–Vinh and Ho Chi Minh–Nha Trang Sections DRAFT FINAL REPORT


4-1

4 CONSIDERATIONS FOR TUNNELS ALONG HSR ALIGNMENT

4.1 General

4.1 Tunnels will be planned to satisfy the social requirements, law, legal regulations and necessary infrastructure assessing at the natural condition of the tunnel route including topography, geology and hydrology, environmental impact to the nature, accessibility in the maintenance stage for safety control and economical efficiency, etc.

4.2 Advantage and disadvantage of tunnels are listed in Table 4.1.1.

Table 4.1.1 Advantage and Disadvantage of Tunnels

Advantage Possible to connect two points with minimum time and minimum distance.

To reduce land acquisition cost. Stable to the natural disasters such as typhoon, flood,

slope collapse, land slide, etc. Easy and economical for maintenance. Impact zone of vibration and noise caused of travel

pass shall decrease. No disturbance of the ground surface. Total construction cost shall be cheaper than detouring

route. Small impact to the destruction of forest and natural

environment and to be easier to sustain the ecological system.

Less damage to the landscape. Disadvantage Construction period shall be longer than the ground

works because the accessible points are limited. Shortage of groundwater is anticipated. Generally, tunnel construction shall be more expensive

than the ground surface works. Major issue is to ensure the safety of passengers

against fire accident. Source: JICA Study Team

4.3 Planning, design and construction of tunnel projects have their own difficulties because details of natural conditions such as geology, hydrology, environmental impact, and so on, are uncertain before and during the tunnel construction.

4.4 Tunnels in the HSR route are designed by the NATM because most of tunnels will be constructed in the soft to hard rocks. Primary design of the NATM tunnels will be modified appropriately during the tunnel construction by feeding back the result of monitoring.


4-2

4.2 Design for Tunnel

1) Necessity of Tunnels

4.5 Tunnel is a very effective way to connect two places between which it is difficult to access directly due to some constraints such as mountain, strait, and so on. Tunnel also helps shortening the travel time and the route length to reduce the construction and maintenance cost. However, alignment and section area of tunnels are restricted by not only natural conditions but also the purpose of tunnel, types of traffics, types of vehicles, etc. Therefore, tunnel should be planned to appreciate the intended use.

2) Tunnel Alignment

4.6 Railway alignments are usually regulated in the railway specifications. Vertical and horizontal alignment of tunnel are designed to satisfy the function and the purpose of the tunnel as a part of the railway considering the topography, geology, land use, environmental conditions which are obtained from the results of the field survey.

4.7 In case two or more tunnels already existed close near to the planned tunnel, disturbances of those tunnels should be taken into account.

4.8 Additional adit and ventilation shaft shall be considered for the construction of tunnel.

4.9 The grading of the tunnel for the vertical alignment is planned more than +/-0.3 % to keep natural dewatering during construction.

4.10 Up-graded from both portals should be designed for the long tunnel more than 1,000 m to avoid wastewater concentration to the one side of the tunnel. This will also help reducing the construction time by excavating from both sides of tunnel portals.

3) Tunnel Cross Section

4.11 The tunnel gauge and inner section of the tunnel shall be designed according to the type and purpose of the tunnel. Inner section shall be determined from the tunnel gauge, ventilation facilities, electric facilities, emergency facilities, railway signs, etc. and the allowable tolerance for the construction error.

4.12 Following items shall be considered when designing railway tunnels.

(i) Estimated Traffic Volume

(ii) Design Speed

(iii) Nos. of Tracks

(iv) Width of Tracks

(v) Width of Shoulder

(vi) Inspection Gallery

(vii) Width of Inspection Gallery

(viii) Vertical Clearance

4.13 Generally, railway tunnel cross section is designed empirically by the design standard regulated by the railway authority considering a purpose and usage of the tunnel. Tunnel support system is designed by the empirical method based on the experiences of huge numbers of railway tunnels. Numerical analysis using FEM, DEM and so on, shall be applied for the design of the special sections and/or the tunnel planned under the special



4-3

conditions, such as large section more than 100 m2 to 120 m2, intersection of two tunnels, swelling & squeezing rocks, soft ground, etc.

4.14 Figure 4.2.1 and Table 4.2.1 show the standard cross section assumed for HSR and the Japanese Bullet Express Railway (Shinkansen) tunnels constructed in 2010, respectively.

with invert without invert


Figure 4.2.1 Standard Cross Section of Tunnel for HSR

Table 4.2.1 Shinkansen (Bullet Railway) Tunnels Completed in 2010 (Length > 2,000 m)

Tunnel Name Length (m) Section Area (m2)

Geology Driving Method Support

Axially Support Excavation Inner Area

Shin Moheji 3,255.0 79.6 62.0 C.S.SR BR R.C.S. FC Toshia Toubetu 8,080.0 73.2 65.5 S.SR BR R.C.S. FC Tsugaru Hasuda 6,250.0 100.3 54.6 S.G.SR AS O Iiyama (Itakura) 3,669.0 82~105 63.0 SP BR.DO R.C.S. FP.PP Matsunoki 6,720.0 63.5 63.5 G.S.SP MR.BR R.C.S. FR.FB. Tawarazaka (E) 2,470.0 74.0 64.0 S.SR MR.BR R.C.S. FP Tawarazaka (W) 3,030.0 74.0 64.7 SR.HR MR R.C.S. PP Sonogi 3,520.0 74.0 64.0 SR.HR MB.MR R.C.S. FP Misaka (E) 3,025.0 95.0 85.0 HR BB R.C.S. Misaka (Middle) 2,225.0 89.4 83.6 G.HR FB R.C.S. Misaka (W) 2,860.0 91.4~95.8 80.0 HR MB.BB R.C.S. FP.FC.PP Akiyama 2,890.0 30~150 80.0 SR.HR MB.BB R.C.S. Akiyama 3,805.0 99.0 82.0 SR.HR BB R.C.S.

Source: Annual Report of Tunnels, JTA (Japan Tunneling Association) Notes: Abbreviations described above are as followings:

Geology Driving Method Support Type Axially Support

C: Clayey Soil BR: Bench cut R: Rock bolt FC: Face shotcrete S: Sandy Soil AS: Shield C: Shotcrete FP: Fore poling SR: Soft Rock (swelling) DO: Heading S: Steel support PP: Fore Piling G: Grabel MR: Mini bench O: Others SP: Soft Rock BB: Bench cut HR: Hard Rock FB: Full face



4-4

4.3 Rock Classification of Tunnels

4.15 Rock classification applied for tunnels is inevitable for the decision of the tunnel driving method and the excavation method of tunnels, selection of the suitable tunnel support pattern and cost estimation of the project.

4.16 Rock mass classification schemes have been developed for over 100 years since Ritter (1879) attempted to formalize an empirical approach to tunnel design, in particular for determining support requirements.

4.17 The multi-parameter classification schemes commonly referred for the rock classification of the NATM are the Q-System (1989, and Barton et al.) and RMR (Bieniawski, 1989). Rock classification of the Hai Van pass tunnel construction project was defined based on the RMR.

1) Q-System

4.18 The traditional application of the six parameters Q-value regarding the types of joints of rock mass has advantage to select suitable support members of jointed rocks, such as shotcrete, rock bolt, etc. However, traditional Q-System is too complicated to apply for the judgment of daily tunnel work. Revised Q-System has been developed including RMR, seismic velocity of rock mass, etc.

4.19 Figure 4.3.1 shows the revised Q-System issued in 2002.

Reference: Some Q-Value correlations to assist in site characterization and tunnel design (N. Barton 2002, Int. Journal of Rock Mech. And Mining Sci.)

Figure 4.3.1 System (Revised in 2002)

2) Rock Mass Rating (RMR)

4.20 RMR value is calculated by the six parameters written in Figure 4.3.1. One parameter “Orientation of Discontinuities” is correlated with the dip and strike of joints available for selecting the support members.

4.21 Figure 4.3.2 shows the RMR issued in 1989.



4-5

A. CLASSIFICATION PARAMETERS AND THEIR RATINGParameter Range of value

1 Strength of Point-load >10 MPa 4-10 MPa 2-4 MPa 1-2 MPaintact rock strength indexmaterial Uniaxial comp. strength >250 MPa 100-250 MPa 50-100 MPa 25-50 MPa 5-25 MPa 1-5 MPa <1 MPa

15 12 7 4 2 1 02 90-100 % 75-90 % 50-75 % 25-50 %

20 17 13 83 > 2 m 0,6-2 m 200-600 mm 60-200 mm

20 15 10 84 Very rough surfaces Slightly rough sur- Slightly rough sur- Slickensided surfaces Soft gouge >5mm

Not continuous. No faces. Separation faces. Separation or Gouge <5 mm thick thick or Separa-separation. Unweath- <1mm. Slightly <1mm. Highly or Separation 1-5 mm. tion >5 mm.

red wall rock weathered walls. weathered walls. Continuous.30 25 20 10

5 Ground water Inflow per 10 m tunnel length (l/m) None <10 10.0-25.0 25-125(Joint water press.) / (Major principal 0 <0.1 0.1 - 0.2 0,2 - 0,5

General condition Completely dry Damp Wet Dripping15 10 7 4

B. RATING ADJUSTMENT FOR DISCONTINUITY ORIENTATIONS (See D)Strike and dip orientation Very favourable Favorable Fair Unfavourable

Tunnels & mines 0 -2 -5 -10Foundation 0 -2 -7 -15

Slopes 0 -5 -25 -50

C. GUIDELINES FOR CLASSIFICATION OF DISCONTINUITY CONDITIONSDiscontinuity length (persistence) <1 m 1-3 m 3-10 m 10-20 mRating 6 4 2 1Separation (aperture) None <0.1 mm 0.1-1.0 mm 1-5 mmRating 6 5 4 1Roughness Very rough Rough Slightly rough SmoothRating 6 5 3 1Infilling (gouge) None Hard filling<5 mm Hard filling>5mm Soft filling <5 mmRating 6 4 2 2Weathering Unweathered Slightly weathered Moderately weathered Highly weatheredRatings 6 5 3 1

D. EFFECT OF DISCONTINUITY STRIKE AND DIP ORIENTATION IN TUNNELING

For this low range - uniaxial compressive test is preferred

Rating Drill core Quality RQD < 25 %

Rating 3Spacing of discontinuities <60 mm

Rating 5Condition of discontinuities

(see C)

ContinuousRating 0

>125>0.5

FlowingRating 0

>20 m

Very Unfavourable-12

Ratings -25

0>5 mm

0Slickensided

0Soft filling >5 mm

0Decomposed

0

Strike perpendicular to tunnel axis Strike parallel to tunnel axisDrive with dip-Dip 45-90o Drive with dip-Dip 20-45o Dip 45-90o Dip 20-45o

Very favourable Favourable Very unfavourable FairDrive against dip-Dip 45-90o Drive with dip-Dip 45-90o Dip 0-20 - Irrespective of strike

Fair Unfavourable Fair Source: Z.T. Bieniawski, “Engineering Rock Mass Classification, Join Wiley & Sons, Inc, 1989)

Figure 4.3.2 Rock Mass Rating

3) Rock Classification of the Hai Van Pass Tunnel Construction Project

4.22 Geology of Hai Van Pass Tunnel is composed of highly to completely weathered granite distributed in the portal area and fresh and hard granite (Triassic Period of Mesozoic Era).

4.23 Before commencement of tunnel construction, rock classification of the project was defined by the geotechnical engineer of the consultant and submitted to the client (PUM-85) for approval.

4.24 Rock classification of the Hai Van Pass Tunnel Project includes the following items correlating with the RMR.

(i) Description of Geological Condition

(ii) Rate of weathering of rock surface

(iii) Numbers of systematic joints

(iv) Joint spacing and persistence of joint

(v) Condition of joint

(vi) Blow of geological hammer

4.25 Table 4.3.1 shows the “Rock classification of the Hai Van Pass Tunnel Project” while Table 4.3.2 shows the rock type and classification of Japan Railway Construction, Transportation and Technology Agency for reference.


4-6

Table 4.3.1 Rock Classification in Hai Van Pass Tunnel

Rock Class

Geological Condition Color of Rock Surface

(Granite) Correspond RMR Value

Support Type

A Rock face is completely Fresh to fresh. Minerals and matrix of rock are non-altered or rarely altered. Small amount of non-systematic joint and/or fracture due to blasting is observed. Spacing of joins is more than 2 m. Persistence of joints is less than 1 m. Rock is hard to break under heavy blow of geological hammer.

Original Color (white and black dotted) or gray.

100 to 70 I

B Rock face is fresh to comparatively fresh. Minerals and matrix of rock slightly weathered, but it's original color have never changed. One to two set of systematic joints are observed. Spacing joint is 0.6 m to 2 m and persistence of joints is 1 m to 3 m. Rock will break along to the joint plane under heavy blow of geological hammer.

Original Color (white and black dotted) or gray.

80 to 60 II

CI Rock face is comparatively fresh to moderately weathered. Color minerals, such as mica, hornblende, etc., are slightly weathered along to joint plane. One to two set of systematic joint and several numbers of non-systematic joints are distributed. Sometime, thin layer of sandy or clayey material is coating on the surface of joint plane. Spacing of systematic joint is 200 mm to 600 mm. Rock will break along to joint under moderately blow of geological hammer.

Mainly white color. Pale brown color is observed along to joint.

70 to 40 III

CII Rock face is moderately weathered and highly weathered zone is observed along to discontinuities. Rock mass become blocky, however, each blocks are still contacted. Colored minerals is moderately weathered and original color of minerals are altered. Sometimes, feldspars are altered to clay minerals. Less then three set of systematic joint set and random joints are existing. Spacing of systematic joints is 60 mm to 200 mm. Joints are open in several widths (less than 5 cm) and filled with filling materials. Rock is easily to break along to joint. Rock block remaining is still hard and break under moderately blow of geological hammer.

Mainly white to white brown. Brown to reddish brown color is observed around joints.

30 to 60 IV

DI Rock face is highly weathered and sandy to clayey material is coating on the surface of remaining blocky rock. Colored minerals are highly weathered and altered to clayey materials. Each rock blocks are separated due to joints. Original texture of rock is still remaining in each rock block. Decomposed zone, such as fractured zone or crush zone, may be distributed. Less than four sets of systematic joins and random joins are observed. Joint plane is opening 5 cm to 10 cm and filled with filling materials. Predominant spacing of joints is 20 mm to 60mm. Rock is easily to break under weak blow of geological hammer.

Pale yellow to yellow brown. Brown to reddish brown color is observed around discontinuities.

25 to 50 V

DII Highly weathered and/or decomposed. Rock surface is covered with thick sandy to clayey materials. Colored minerals are altered to sandy materials and feldspars are altered to clay. Distribution of joints becomes not clear and apparent spacing of joints to be wide. Joint is filled with filling materials. Ease to break, and sometimes hammerhead will penetrate under week blow of geological hammer.

Yellow brown to reddish brown.

20 to 40 VI-A

E Decomposed and/or disintegrated to soil. Joints and discontinuities are hard to observe. Easy to collapse or hammerhead penetrates under light blow of geological hammer.

Reddish brown to red.

less than 20 VI-B

Source: Hai Van Pass Tunnel construction project



4-7

Table 4.3.2 Rock Type and Classification for Railway in Japan

(a) Rock Classification by the Seismic Wave Velosity Type of

Rock Rock Class

Rock Type A

Rock Type B

Rock Type C

Rock Type D

Rock Type E

Rock Type F & G

Clayey Soil Sandy Soil

VN Vp≥5.2 null Vp≥5.0 Vp≥4.2 null null null IVN 5.2>Vp≥4.6 null 5.0>Vp≥4.4 4.2>Vp≥3.4 null null null

IIIN 4.6>Vp≥3.8 Vp≥4.4 4.4>Vp≥3.6 3.4>Vp≥2.6 & Gn≥5

2.6>Vp≥1.5 & Gn≥6

null null

IIN 3.8>Vp≥3.2 4.4>Vp≥3.8 3.6>Vp≥3.0 2.6>Vp≥2.0 & 5>Gn≥4

2.6>Vp≥1.5 & 6>Gn≥4

null null

IN-2 3.2>Vp≥2.5 null 3.0>Vp≥2.5

2.6>Vp≥2.0 & 4>Gp≥2, or 2.0>Vp≥1.5

& Gn≥2

2.6>Vp≥1.5 & 4>Gn≥3

null null

IN-1 null 3.8>Vp≥2.9 null Null 2.6>Vp≥1.5 & 3>Gn≥2

Gn≥2 Dr≥80 & Fc≥10

IS

2.5>Vp 2.9>Vp 2.5>Vp

1.5>Vp or 2>Gn≥1.5

1.5>Vp or 2>Gn≥1.5

2>Gn≥1.5 null IL null Dr≥80 & 10>Fc

Special Type S 1.5>Gn 1.5>Gn

1.5>Gn null Special Type L null 80>Dr

Vp:Seismic Wave Velosity (km/sec) Gn: Competence Factor Dr: Relative Density

Fc: Fine Fraction Content

(b) Rock Type

Rock Type

Geological Age, Rock Type and Name of Rocks Classification by the Uni-axial Strength

A

1. Sedimentary Rocks in Paleozoic & Mesozoic Era. (Slate, Sand stone, Conglomerate, Chart, Limestone, etc.) 2. Plutonic Rocks (Granite Group 3. Hypabyssal Alteration Rocks (Phophyrite, Grano-Phophyry, etc.) 4. Some types of Volcanic Rocks (Intact Basult, Andesite, Rhyorite, etc.) 5. Metamorphic Rocks (Schist, Gneiss, Phyllite, Hornfels, etc.)

Uni-axial Strength is roughly estimated as a following value.

50N/mm2≤qu

Massive Hard Rock (Non-fissility from Discontinuities)

B

1. Fissility dominated Metamorphic Rocks (Schist, Phyllite, Gneiss) 2. Fissility dominated thin bedded Sedimentary Rocks of Paleozoic & Mesozoic Era. (Slate, Shale, etc.) 3. Volcanic Rocks with many discontinuities. Cracky and Fissility Hard Rocks.

C 1. Sedimentary Rocks in Mesozoic Era (Shale, Slate, etc.) 2. Volcanic Rocks (Rhyorite, Andesite, Basalt, etc.) 3. Sedimentary Rocks in Paleogene Period (Shale, Mudstone, Sandstone, etc.)

D

1. Sedimentary Rocks in Neogene Period (Shale, Mudstone, Sandstone, Conglomerate, Tuff, etc.) 2. Some Sedimentary Rocks in Paleogene Period 3. Weathered Volcanic Rocks.

15N/mm2≤qu ≤50N/mm2

E

1. Sedimentary Rocks in Neogene Period (Shale, Mudstone, Sandstone, Conglomerate, Tuff, etc.) 2. Weathered Rocks, Hydrothermal Alteration Rocks and Crushed Rocks (Volcanic Rocks, Metamorphic Rocks, Sedimentary Rocks (older than Neogene Period)

2N/mm2≤qu≤15N/mm2

F

1. Sediments in Pleistocene Period (Low to Unconsolidated Sediments composed of Grable, Sand, Silt, Mud and Tuff) 2. A part of Sediments in Neogene Epoch (Low to Unconsolidated Deposits, Hard Clay, Sand, etc.) 3. Highly to Completely Weathered Granite.

qu<2N/mm2

G Surface Soil, Talus Deposits, Collapsed Deposits.

Source: Japan Railway Construction, Transportation and Technology Agency


4-8

4.4 Tunnel Construction Method

1) Concept of the Tunnel Construction

4.26 Driving method and excavation method of tunnel should be planned considering the following items: 1) Safety; 2) Faster; 3) Low Cost; 4) No Environmental Pollution

2) Tunnel Driving Method

4.27 Drill and Blast, Mechanical Excavation and Tunnel Boring Machine are typical methods for tunnel driving method as explained in Table 4.4.1.

Table 4.4.1 Tunnel Driving Method

Blasting Method Mechanical Excavation Tunnel Boring Machine (TBM)

Scheme

Sato Kogyo Co., Ltd.

Sato Kogyo Co., Ltd.

Sato Kogyo Co., Ltd. (Hida Tunnel)

Abstract Insert blaster into blasting hole and blast using detonator.

Tunnel face and sidewall is excavated mechanically using universal and/or special type machine.

Fully mechanized Full Face and/or Heading Section type machine.

Shield Type, Half and/or Semi Shield Type, Open Type TBM are applied.

Equipment & Materials

Dynamite, ANFO, Surry Explosives, etc.

Electric Detonator and Non-Electric Detonator etc.

Road Header, Breaker, Boom Header, special types of Excavator are available to use for excavation

Tunnel Boring Machine, Control Unit, Electric Unit, etc.

Feasible Geology

Hard Rocks to Medium Hard Rocks Medium Hard Rocks to Soft Ground.

Hard Rocks to Medium Hard Rocks

Advantage Applicable to every type of tunnel. Suppliers have developed many

types of blasters and detonators. Advance of one cycle and support

system is changeable by the inspection of tunnel face after excavation.

Smooth excavated surface shall be got by the smooth blasting.

Almost applicable to the every types of tunnel where machine is accessible.

Possible to minimize over break. Useful for the construction in urban

area.

Rapid excavation advance. Smooth excavated surface effective

to reduce stress concentration around tunnel.

Almost all works and activities shall be done under the shield.

Disadvantage

Tunnel advance is highly affected by the skillfulness of worker.

Over break shall be larger than the other method.

High level noise, dust, vibration.

High level noise, dust and vibration. Excavation speed depends on the

skillfulness of the operator. Machine shall work under

unsupported surface.

No flexibility against the change of geology.

Size of facilities shall be deep.

Cost Cheaper than the TBM excavation. Cheap Expensive Source: JICA Study Team

3) Tunnel Excavation Method

4.28 Various types of excavation are applied for the hard rock to unfavorable ground as listed in Table 4.2.2. Some of those methods are not available in present day due to the development of the new support system and lack of well-trained skillful worker.



4-9

Table 4.4.2 Tunnel Excavation Method

Excavation Method

Scheme Applicable Ground Condition Advantage Disadvantage

Full Face Excavation

Hai Van Pass Tunnel

Almost all ground for small section tunnels.

Very stable ground for large section tunnels (A>60m2)

Fairly stable ground for medium section tunnels (A>30m2)

Mixed ground of good rock and bad rock where change of the excavation method is required.

Labor saving by mechanization

Construction management including safety control is easy because of the single face excavation

Sometimes it shall be difficult to excavate whole tunnel length only by the full face and alternative excavation shall be required.

Unstable stone may fall down from tunnel crown and additional safety measures are required to protect small collapse.

Full Face Excavation with Auxiliary Bench Cut

Sato Kogyo Co.,Ltd.

Fairly stable ground, but difficult for the full face excavation.

This method shall apply instead full face excavation when the stability of tunnel face could not be obtained in the full face excavation.

Relatively good ground even mixed with bad rocks.

Labor saving by mechanization and parallel excavation with top heading and bench.

Construction management with safety control is easy due to the single face excavation.

In case tunnel face becomes unstable, alternative excavation method shall be required.

Change of the excavation method shall take time and cost.

Bench Cut Excavation

Long Bench Cut Method

Fairly stable ground, but difficult for the full face excavation.

Ring cut method shall be used when the face became unstable.

Alternate excavation of top heading and bench reduces equipment and manpower.

Alternate excavation shall elongate the construction time.

Short Bench Cut Method

Ring cut method shall be applied when the tunnel face became unstable.

Adjustable to the sudden change of ground condition.

Alternate excavation of top heading and bench reduces equipment and manpower.

Parallel excavation of top heading and bench shall be unfavorable due to the difficulty to control cycle time.

Length of bench is easily changed to suit the ground condition.

Mini Bench Cut Method

Applicable to the unstable ground.

Possible to make stabilize tunnel face by dividing small heading excavation.

Easy to change to the ring cut excavation remaining center part of face.

Unsupported ground is immediately covered by the preliminary support.

Possible to minimize deformation of ground installing support members to complete closed tunnel structure.

Temporary invert is easy to construct.

Large and usual equipment shall be difficult to use due to the narrow space.

Machine excavation is prevailing and cycle time shall be longer.

Bench Cut Excavation

Multiple Bench Cut Method

Available to use to the fairly good ground and large section.

Small section is required to the unfavorable ground.

Easy to stabilize the face. Deformation of tunnel shall be large due to the delay of support installation.

Large and usual equipment shall be difficult to use due to the limited bench space.

Cycle time is highly affected by the excavation and mucking system.


4-10

Excavation Method

Scheme Applicable Ground Condition Advantage Disadvantage

Center Dia- phragm Method

Usually applied to shallow overburden with soft ground to minimize ground settlement.

Relatively large section area.

Stability of tunnel face shall get to divide full face.

Centre diaphragm is effective to prevent ground settlement.

Cd in upper section and full section is applicable to fit ground condition.

Deformation of tunnel should be measured carefully during removal of center diaphragm.

Additional support member shall be required to stabilize tunnel face.

Drift and heading Method

Side Drift Method with Side Wall

Applied to the large section tunnel with good rock condition.

Ground condition such as geology, water seepage should be inspected before and during tunnel construction.

Relatively massive concrete wall for side drift improve the bearing capacity.

Effective against to the unsymmetrical load acting from the inclines ground surface.

Excavation equipment is limited by the section of side drift.

Construction schedule will be longer than the bench cut etc.

Side Drift Method without Sidewall

Usually applied to the soft ground and/or difficult ground such as swelling, squeezing

Tunnel portal excavation under the unfavorable ground condition.

Effective to protect ground settlement and large deformation of the tunnel.

Section of drift shall be changed to fit the ground condition.

Excavation equipment is limited by the section of side drift.

Construction schedule will be longer than the bench cut etc.

Top Heading and Centre Drift, Bottom Drift Advance

Difficult geological condition such as soft ground, some amount of water seepage.

Effective to stabilize tunnel face and installation of primary support.

Available to predict ground condition in front or tunnel face.

Possible to dewater existing in front of tunnel face.

Large and generalized equipment is difficult to apply as the section of drift is not enough.

Some special equipments or manpower excavation are required.

Those methods shall take long time and shall increase excavation cost.

Top Heading using Tunnel Boring Machine (TBM)

Hamamatsu East Tunnel 2nd Tomei Express Way

Applied to the large section tunnel with good rock condition.

Ground condition such as geology, water seepage should be inspected before and during tunnel construction.

Very effective to shortening construction period.

Difficult to change excavation method when ground conditions become worse.

TBM excavation and enlargement of the tunnel section shall be separated.




4-11

4.5 Tunnel Portal Design

1) Location of Tunnel Portal

4.29 Study of the location of tunnel portal should be taken care of the following factors;

(i) Topology, geology of the portal area

(ii) Overburden thickness around the tunnel portal

(iii) Environmental conditions around the tunnel portal.

(1) Topography and Geology

4.30 Generally, tunnel portal area is characterized by the following conditions.

(i) “Ground Arch” important for the self-support effect of the ground shall not formed due to thin overburden.

(ii) Many disasters such as slope collapse, landslide, ground settlement, uneven load, etc. are anticipated during construction.

(iii) Natural disasters such as rock fall, mudflow, earthquake, flood and heavy rain may happen even in operation stage of railway.

(iv) Change the acting load to tunnel due to land development.

4.31 Topography and geology required special care is listed in Table 4.5.1.

Table 4.5.1 Remarkable Points for Determination of the Tunnel Portal

Topographic Character

Portal at the mountain ridge

Thickness of weathered zone shall be longer than the others. Heavy load shall act on the support at the horseback shape

mountain ridge. Portal at valley Surface water shall concentrate to the valley.

Talus deposit and rock debris shall cover ground surface. Flood and mud flow are anticipated in rainy season. Geomorphologic analysis (summit level map) is recommended

to examine the old topography. Portal almost right angle to slope

Stable type of portal. Spall and loose stone should be removed.

Portal parallel to counter line

Uneven rock load shall act to the tunnel support. Countermeasures shall be placed against to the uneven load.

Geology and Environments

Slope Failure or Landslide

Slope collapse or landslide may occur above tunnel portal due to insufficient way of slope cut.

Slope collapse or landslide is anticipated before tunnel excavation, monitoring of the slope should be planned.

Insufficient bearing capacity of ground

Settlement of tunnel structure shall happen when the bearing capacity of the ground at the toe of supports is less.

Steel plate, foot bolt, bearing concrete should be placed to reinforce the bearing capacity of the ground.

Face collapse Tunnel face shall not be stable due to unfavorable ground conditions such as weathering, water seepage, etc.

Fore poling, face bolt, steel ribs shall be required. Settlement of ground surface

Ground settlement shall be anticipated if sufficient support is not installed.

Reinforcing of support members should be considered. Monitoring of the tunnel deformation and ground settlement

should be done. Neighboring structure Tunnel construction will affect the neighboring structures such as

buildings, roads, railways, electric power line and tower, etc. Source: JICA Study Team


4-12

(2) Overburden of the Tunnel Portal Area

4.32 Desirable thickness of overburden at the tunnel portal is commonly considered more than 1.5D to 2.0D (D: tunnel diameter) to have a “Ground Arch Effect” available to reduce the support members as shown in Figure 4.5.1. However, location of tunnel portal should be selected considering topography and geology of each tunnel.


Figure 4.5.1 Area of Standard Portal Zone (Highway Tunnel)

4.33 Collapse of tunnel crown/arch may happen when the tension stresses occur at the tunnel crown and the magnitude of redistributed stress exceeds the tension strength of surrounding rocks. Result of numerical analysis of tunnel indicates that the tension zone gradually disappear when the overburden thickness increases.

(3) Environment around Tunnel Portal

4.34 Tunnel portal is the only point connecting the underground and the open air. Location of tunnel portal should be taken account of the following environmental impacts.

(i) Blasting noise and noise by the machine operation.

(ii) Low frequency vibration caused by blasting.

(iii) Polluted air blown out from exhaust duct.

(iv) Air burst due to railway.

2) Tunnel Entrance

4.35 Tunnel entrance should be designed in order to

(i) Protect the tunnel portal against rock fall, slope collapse and other disasters.

(ii) Avoid the settlement and the deformation of entrance structures.

(iii) Harmonize with surrounding nature landscape.

4.36 Ordinary types of entrance structures for railway tunnel are shown in Table 4.5.2.



4-13

Table 4.5.2 Tunnel Entrance Structure

Retaining Wall Type Wall Type Limb Type

Scheme

Shiromaru T Tokyo

Funaba T Chugoku Ex. Way.

Kuraki T Chugoku Ex. Way

Applicability Moderately to steeply inclined slope where retain wall for the slope protection is required.

Large amount of rock fall is anticipated.

This type is not popular in present stage.

Moderately to steeply inclined slope where slope cut need for the tunnel portal construction.

In case of tunnel route is intersecting with slope in shallow angle, protecting countermeasures is required against the uneven load.

Applied to the moderately inclined slope.

Bank for countermeasure of slope collapse is constructed.

In case of the slope work around tunnel portal has no difficulty.

Remarks Installation of pillar or improvement of foundation is required in bad geology.

Entrance wall should be combined with tunnel lining structure.

Length of tunnel shall be long. Countermeasures should be

considered. Source: JICA Study Team


4-14

4.6 Standard Support System for the HSR Tunnels

1) Standard Support Pattern

4.37 Tunnel standard support pattern is assumed by the empirical method referencing the “Hai Van Pass Tunnel” which is the only one long tunnel in Viet Nam constructed for NH1. As section area of Hai Van Pass Tunnel is nearly 25% larger than the HSR tunnels, this standard support pattern is applicable to HSR tunnels. The more appropriate support system for HSR tunnels shall be designed in the detail design stage.

4.38 Table 4.6.1 shows the standard support pattern for HSR tunnels considering the standard support pattern of Hai Van Pass Tunnel. Table 4.6.2 shows the support system for Shinkansen tunnels of Japan for reference.

Table 4.6.1 Standard Support Pattern of HSR Tunnel

Support Type

Correspond RMR Value

Round Advance

Excavation Section (m2)

Shotcrete (mm)

Rock Bolt Wire Mesh (per 1.0m)

Steel Rib Fore poling

I 100 to 70 ; 92.66

SN Type L=3 m Temporally

II 80 to 60 2 m 92.66 50 SN Type L=3 m Spacing 2 m 13.5nos.

CQS6 25.59 m

III 70 to 40 1.5 m 93.95 100 SN & Swell xL=3 m L. Spacing 1.5 m 15.5nos.

CQS6 25.59 m

IV 30 to 60 1.2 m 93.95 100 SN & Swell xL=3 m L. Spacing 1.2m 15.5nos.

CQS6 25.59 m

H-125 x 125

V 25 to 50 1.0 m 95.25 150 SN & IBO L=4 m L. Spacing 1 m 19.5nos.

CQS7 25.59 m

H-125 x 125

IBO L=3 m 16.5 nos

VIA 20 to 40 1.0 m 117.74 20 SN & IBO L=4 m L. Spacing 1 m 19.5nos.

CQS7 25.59 m Double layers

H-150 x 150

IBO L=3 16.5 nos

VIB less than 20 Special support pattern Source: JICA Study Team based on the basic principle of NATM by N.N.Lan, Ho Thanh Son.

Table 4.6.2 Support System for Shikansen Tunnels

Double track rail tunnel for Shinkansen: excavation diameter about 10, to 11m Support

Members Standard Support Type

Rock Bolt Thickness of Shotcrete Steel Support

Arrangement Length (m)

Quantity (Numbers)

Longitudinal Spacing (m)

Arch Sidewall Invert Type

IVNP null null null null 5 (average) null null IIINP Arch 2 0~6 Optional 10 (average) null null ＩＩNP Arch 3 10 1.5 10 (average) null null

INP Arch,

Sidewall 3 14 1 15 (minimum) null 125H(*2)

ISP Arch,

Sidewall 3 8

1 15 (minimum) 15

(minimum) 150H 4 (*1) 12 (*1)

ILP Arch, Sidewall 3 12 1 20 (minimum) null 125H

Note:(*1) 4m rockbolt re-arranged around the spring line (arch foot & sidewall (*2) When steel support is adopted, the type given parentheses is used. Suffix P in standard

support pattern represent "Pattern" in order to avoid confusion with class of ground Source: Japan Railway Construction, Transportation and Technology Agency (Translated by JSCE)



4-15

2) Support Pattern for Each Tunnel

4.39 Geology of HSR tunnels are roughly estimated based on the result of geology map in Viet Nam, result of geological inspection and survey borings. Geology and length of support patterns at the tunnel portal area and the inside of tunnel are assumed as shown in Table 4.6.3 and Table 4.6.4.

4.40 Details of support pattern for each tunnel should be decided in the detail design stage.

Table 4.6.3 Tunnel Location from Hanoi to Vinh

No Location Kilo Post Length

(m) Overburden (m)

Length (m) of Support Pattern Estimated Geology

From To max min II to III V

1 Tam Diep 110,760 114,390 3,630 63 12 1,000 2,630 *Upper subformation :massive limestone, dolomitized limestone 300-450 m thick *Lower subformation: limestone, marl,cherty limestone, 300-450 m thick *Dong Giao formation: Upper subformation light-colored massive limestone marl. Major fault is crossing at the center part nearly right angle.

2 Ha Trung 124,010 124,810 800 34 0 0 800 *Dong Son formation : quartzitic sandstone ,siltstone ,calcareous sandstone,360 m thick *Ham Rong formation: sandstone, siltstone, sandy limestone, colithic limestone, cherty. No major fault is written in geology map.

3 Hoang Khanh 1

134,960 135,280 320 29 - 0 320 Ham Rong formation: sandstone, siltstone, sandy limestone, colithic limestone, cherty limestone 500-600 m thick. No major fault.

4 Hoang Khanh 2

136,510 138,150 1,640 245 16 950 690 Dong Son formation: quartzitic sandstone, siltstone, calcareous sandstone, 360 m thick. No major fault is written in geology map.

5 Thanh Ky 1 188,640 190,490 1,850 154 20 1,610 240 Dong Do formation: Upper subformation: red-colored sandstone, conglomerate, gritstone, 500-900 m thick. No major fault is written in geology map.

6 Thanh Ky 2 191,230 192,670 1,440 171 - 960 480 Dong Do formation: Upper subformation: red-colored sandstone, conglomerate, gritstone, 500-900 m thick. No major fault is written in geology map.

7 Quynh Vinh 208,730 210,860 2,130 95 12 1,380 750 Dong Trau formation: Upper subformation: limestone, marl.600 m thick. No major fault is written in geology map.

8 North Vinh 261,200 264,790 3,590 294 12 3,290 300 Upper subformation; sandstone, silt stone, intercalated with shale, about 1000m thick. Unconformity of Palepzoic and Mesozoic Rocks.

Total 15,400 - - 9,190 6,210



4-16

Table 4.6.4 Tunnel location from HCMC to Nha Trang

No Location Kilo Post Length

(m) Overburden (m)

Length (m) of Support Pattern Estimated Geology

From To max min II to III V

1 Ca Na 247,940 261,550 13,610 744 - 13,090 520 Talus deposit is distributed at South Portal. Tunnel passes through along the mountain ridge. Geology in both portals may compose of the weathered rock of granitedan and porphyrite on Mesozoic Era.

2 Co Lo Mountain

309,350 313,060 3,710 300 36 3,610 100 Rhyrite and decite are mainly distributed and granodiorite observed at north portal. Talus in both portals seems not thick.

3 Cam Ranh Bay 1

321,905 322,196 291 59 - 191 100 Composed of rhyrite, dacite. Short tunnel with thin overburden. Thickness of weathered zone is more than 50m from both portals.

4 Cam Ranh Bay 2

324,927 325,342 415 48 - 0 415 Granite intruded to rhyorite and dacite. Thermal alteration observed at contact zone. Weathered zone may spread trough whole length of tunnel.

5 Hon Rong Mountain

326,680 331,625 4,945 553 - 4,445 500 Mainly composed with granite intruded into grano diorite of same period. Talus deposit spreading at both portals.

6 Hon The Mountain

342,585 344,737 2,152 128 8.6 1,602 550 Composed of medium to coarse granite. Shallow overburden area exist at south portal and at centre part of tunnel and total length will be 550m

7 Hon Nhon 348,046 355,644 7,598 800 - 7,398 200 Mainly composed of rhyrite and dacite of Nha Trang Formation and granite intruded to them. Talus deposit is anticipated at both portals.

8 Nha Trang 355,945 356,395 450 60 24 0 450 Composed of rhyrite, dacite of Nha Trang Formation. Thickness of weathered zone is less than 10m form ground surface. Tunnel is passing parallel to the counterline and uneven load is predicted.

9 Hon Ngang Mountain

359,650 360,758 1,108 60 0 608 500 Granite intruded to Nha Trang Formation and thermal alteration zone is spreading along the contact zone. Land development is under construction near the center part of tunnel.

Total 34,279 - - 30,944 3,335 Source: JICA Study Team



4-17

4.7 Monitoring

4.41 During tunnel excavation, surrounding ground of tunnel will move toward the inside of the tunnel as the existing ground disappears and, sometimes, the deformation shall bring about the collapse of the tunnel.

4.42 Fundamental concepts for the construction management of the NATM are;

(i) To analyze and to feed back daily monitoring results to the next cycle of excavation.

(ii) Support pattern for newly excavated area is determined based on the observation of the geology of tunnel face and the displacement around tunnel face.

(iii) Support pattern will be designed appropriately to bring out the self-standing effect of ground, to minimize loosening zone around tunnel, and to reduce construction cost effectively.

(iv) Instruments of monitoring will be available to use for the tunnel maintenance during operation.

4.43 A sample of the daily observation chart for tunnel face applied in Hai Van Pass Tunnel Construction Project is shown in Table 4.7.1.


igh Speed Railw


o Chi M


FINAL R

EPOR

T Technical R


ap

4-18

Tab

le 4.7.1 Daily O

bservatio

n C

hart

Source: Hai Van Pass Tunnel construction project

Contractor: Tunnel Engineer:

Inspector: Geotechnical Engineer:

Development

Present Face

Behind Face

A B C D E

Photo

Face observation

Face Sta. Numbe

PHOTO

SketchJoint D

1234

5

A E

C

B D

Part 1 Package:

Station: Date: RMR point(a+b+c+d+e+f):

Distance from Portal: m Rock class: Support type:

Auxiliary method: Additional support: Overburden: m

Part 2

A. CLASSIFICATION PARAMETERS AND THEIR RATING

Parameter Range of v alue

1 Strength of Point-load >10 MPa 4-10 MPa 2-4 MPa 1-2 MPa

intact rock strength index

material Uniaxial comp. >250 MPa 100-250 MPa 50-100 MPa 25-50 MPa 5 to 25 1 to 5 <1

strength MPa MPa MPa

a 15 12 7 4 2 1 0

2 90-100 % 75-90 % 50-75 % 25-50 %

b 20 17 13 8

3 > 2 m 0,6-2 m 200-600 mm 60-200 mm

c 20 15 10 8

Very rough Slightly rough Slightly rough Slickensided

surf aces. Not surf aces. surf aces. surf aces or Sof t gouge >5mm

4 continuous. No Separation <1mm. Separation <1mm. Gouge <5 mm thick or

separation. Slightly Highly thick or Separation >5 mm.

Unweathred weathered weathered Separation 1-5 mm.

wall rock walls. walls. Continuous.

d 30 25 20 10

Inf low

per 10 m length None <10 10.0-25.0 25-125

5 Ground of tunnel (l/m)

water (Joint water

press.) / (Major 0 <0.1 0.1 - 0.2 0,2 - 0,5

principal � General Completely Damp Wet Dripping

condition dry

e 15 10 7 4

B. RATING ADJUSTMENT FOR DISCONTINUITY ORIENTATIONS (See D)

Strike and dip orientation Very f av orable Fav orable Fair Unf av orable

Tunnels & mines 0 -2 -5 -10

f Rating Foundation 0 -2 -7 -15Slopes 0 -5 -25 -50

C. GUIDELINES FOR CLASSIFICATION OF DISCONTINUITY CONDITIONS

Discontinuity length (persistence) <1 m 1-3 m 3-10 m 10-20 m

Rating 6 4 2 1

Separation (aperture) None <0.1 mm 0.1-1.0 mm 1-5 mm

Rating 6 5 4 1

Roughness Very rough Rough Slightly Smooth

rough

Rating 6 5 3 1

Inf illing (gouge) None Hard f illing Hard f illing Sof t f illing

<5 mm >5mm <5 mm

Rating 6 4 2 2

Weathering Unweathered Slightly Moderately Highly

weathered weathered weathered

Ratings 6 5 3 1

D. EFFECT OF DISCONTINUITY STRIKE AND DIP ORIENTATION IN TUNNELLING

Part 3: Deformation of Tunnel (Check Following Items)

Rock Fall Hollow Sound Fault or Crushed Water Seepage Sidewall Water

Crack Collapse Rock Bolt Bolt Head Def orm Nut Fall Out Water

Def orm Yield Water

Other Description:

compressiv e test is pref erred

Rating

Drill core Quality RQD < 25 %

TUNNEL DAILY REPORT FOR FACE OBSERVATION (Main Tunnel)

Cross section No:

For this low range - uniaxial

Rating 5

Condition of discontinuities

Rating 3

Spacing of discontinuities <60 mm

(see C)

Total Value f rom C = Continuous

Rating 0

Rating 0

>125

>0.5

Very Unf av orable

-12

-25

Flowing

0

Slickensided

0

>20 m

0

>5 mm

0

Strike perpendicular to tunnel axis Strike parallel to tunnel axis

Sof t f illing >5 mm

0

Decomposed

Very f av orable Fav orable Very unf av orable Fair

Driv e with dip-Dip 45-90o Driv e with dip-Dip 20-45o Dip 45-90o Dip 20-45o

Driv e against dip-Dip 45-90o Driv e against dip-Dip 20-45o Dip 0-20 - Irrespectiv e of strike

Tunnel Face Rock Fall or Fault

Shotcrete Plate Def ormed

Steel Rib Additional Support

Fair Unf av orable Fair



5-1

5 PREPARATION FOR TOPOGRAPHIC MAP

5.1 General

6.1 Topographic survey intends to develop the comprehensive topographic database with a view to updating existing information and Advanced Land Observing Satellite Data (ALOS), specifically, ALOS PRISM (resolution: about 2.5 m) and ALOS AVNIR-2 (resolution: about 10m) of the survey area. Topographic database is updated by using these data. Thus, plans with 1/10,000 scale is able to be developed. Furthermore, elevation data covering the area shall also be procured to enhance existing elevation data for the study area. Thus, it is possible to develop 1/10,000 to 1/25,000 scales of cross-section and profile drawings.

5.2 Methodology

1) Satellite Image Processing

6.2 The following ALOS data shall be purchased and provided to the consultant by the Study Team. A sufficient number of well-distributed map and ground control points shall be used to improve geo-referencing of the ALOS PRISM imagery. The map control points shall be picked using all available topographic map data on the mapping area. Ground controls shall be established with GPS centerline surveys along the selected existing railway and roadway locations in the mapping area. Satellite image processing shall be done using ENVI software.

Table 5.2.1 List of ALOS Purchased

ALOS AVNIR-2 (70 km * 70 km) ALOS PRISM (70 km * 35 km) 1 ALAV2A269723380 1 ALPSMW269723385 2 ALAV2A267243380 2 ALPSMW269723380 3 ALAV2A246383370 3 ALPSMW268993380 4 ALAV2A246383360 4 ALPSMW268993375 5 ALAV2A246383350 5 ALPSMW268993370 6 ALAV2A237633220 6 ALPSMW268993365 7 ALAV2A237633210 7 ALPSMW268993360 8 ALAV2A237633200 8 ALPSMW267243385 9 ALAV2A211083380 9 ALPSMW267243380 10 ALAV2A204083190 10 ALPSMW246383370 11 ALAV2A204083180 11 ALPSMW246383365 12 ALAV2A201893380 12 ALPSMW246383360 13 ALAV2A201893370 13 ALPSMW246383355 14 ALAV2A201893360 14 ALPSMW217793375

15 ALPSMW211083385

16 ALPSMW211083380

17 ALPSMW204083225

18 ALPSMW204083220

19 ALPSMW204083215

20 ALPSMW204083210

21 ALPSMW204083190

22 ALPSMW204083185

23 ALPSMW204083180

24 ALPSMW204083175

25 ALPSMW197373205

26 ALPSMW197373200

27 ALPSMW197373195

Source:


5-2

(1) ALOS PRISM Specifications

Scene Size: 70 km x 35 km

Processing Level: Level 1B2 (Georeferenced)

File Format: Geotiff, 1 band (Panchromatic)

Pixel Depth: 8-bit

Ground Sample Distance (Resolution): 2.5 m

Coordinate System: WGS 84, UTM Zone 48N

(2) ALOS AVNIR-2 Specifications

Scene Size: 70 km x 70 km

Processing Level: Level 1B2 (Georeferenced)

File Format: Geotiff, 4 bands

Pixel Depth: 8-bit

Ground Sample Distance (Resolution): 10 m

Coordinate System: WGS 84, UTM Zone 48N

(3) DEM Data Acquisition

6.3 ASTER 30-m resolution DEM and 2.5m DEM (for possible area) are acquired. The entire project area is covered with approximately 12 tiles of ASTER GDEM data with the following specifications:

(4) ASTER 30-m resolution DEM Specifications

Tile Size: 1º x 1º (110 km x 111 km)

File Format: Geotiff, 1 band

Pixel Depth: 16-bit

Ground Sample Distance (Resolution): 30 m

Vertical Accuracy: ±20 m

Coordinate System: WGS 84

(5) DEM Data Calibration

6.4 The ASTER GDEM is calibrated using all available topographic map data on the mapping area to improve its vertical accuracy.

(6) Digitizing of Planimetry

6.5 Objects that are clearly identifiable on the satellite imagery are digitized and classified according to the following layers:

(i) Roads/Railways

(ii) Settlements or Built Up Areas

(iii) Lakes, Rivers, Streams, Creeks and Ponds

(iv) Irrigation Canals

(v) Vegetation/Crop Lines and other visible landcover types

2) Mapping Area

6.6 The mapping area is shown in followed figures



5-3


Figure 5.2.1 Mapping Area (North) (The Shaded Portion)


5-4


Figure 5.2.2 Mapping Area (South) (The Shaded Portion)

Documents

JICA報告書PDF版(JICA Report PDF) - JAPAN ...Reflecting on the history of railway development in Japan, it is noted that Japan has indeed a great deal of experience in the planning,