NICMAR

CONSTRUCTION OF SEGMENTAL BLOCK REINFORCED EARTHEN

WALL USING GEOGRIDS

“A case study on reinforced earthen walls in outer ring road Hyderabad”

Submitted by:

K.NAVEEN CHAKRAVARTHY Roll No. 233049

V.VIDYASAGAR Roll No. 233090

K.SRINIVAS Roll No. 233093

A Thesis submitted in partial fulfillment of academic requirements for the award of

Post-Graduate Program in Advanced Construction Management

PGPACM XXIII BATCH 2009-11

NATIONAL INSTITUTE OF CONSTRUCTION MANAGEMENT AND

RESEARCH

HYDERABAD

CERTIFICATE

This is to certify that the thesis titled “CONSTRUCTION OF SEGMENTAL

BLOCK REINFORCED EARTHEN WALL USING GEOGRIDS-A CASE STUDY ON

REINFORCED EARTHEN WALLS IN OUTER RING ROAD, HYDERABAD” is the

bonafide work of: K.NAVEEN CHAKRAVARTHY (Roll No. 233049),

V.VIDYASAGAR (Roll No. 233090) and K.SRINIVAS (Roll No. 233093) in partial

fulfillment of academic requirements for the award of Post-Graduate Program in Advanced

Construction Management. This work is carried out by them under my guidance and

supervision.

Date: Signature of the Guide

Hyderabad Prof. R. SATISH KUMAR,

NICMAR, Hyderabad.

Prof. K.R.RAMANA,

Dean-In-Charge

NICMAR’s-CISC

DECLARATION

We declare that the thesis titled “CONSTRUCTION OF SEGMENTAL BLOCK

REINFORCED EARTHEN WALL USING GEOGRIDS-A CASE STUDY ON

REINFORCED EARTHEN WALLS IN OUTER RING ROAD,HYDERABAD” is a

bonafide work carried out by us under the guidance of Prof. R.SATHISH KUMAR. Further,

we declare that this has not formed the basis of award of any degree, diploma, associate ship

or other similar degree or diploma and has not been submitted anywhere else.

Signature Name: K.NAVEEN CHAKRAVARTHY Roll No.233049

Signature Name: V.VIDYASAGAR Roll No.233090

Signature Name: K.SRININVAS Roll No.233093

Date:

Place: Hyderabad

ACKNOWLEDGEMENT

The research thesis is a team work and the satisfaction that accompanies the successful completion

of this task would be incomplete without the mention of the people who made it possible. Though it is

possible to thank them personally, we take this opportunity to express our gratitude to them.

We are deeply indebted and highly obliged to our thesis guide

Prof.R.SATHISH KUMAR, NICMAR, Hyderabad, without whose help we couldn’t have started

the thesis and would not have got any lead for whom to approach and the methodology to be

followed and for guiding and correcting us on the right track.

We also extend our deep gratitude to Mr.K.LAKSHMAN RAO, Project Manager,

Mr.M.SIVA PRASAD, Deputy Project Manager, RAMKY INFRASTRUCTURE, Hyderabad, for

their valuable suggestions and support in carrying out the thesis work in the right path.

We would also thank Prof. K. R. RAMANA, Dean-In-Charge, NICMAR’s-CISC,

Prof.SRI HARI, Deputy Dean, NICMAR’s-CISC for their supporting nature.

We would like to thank our friends studying in various institutes all over

the country in providing us with the relevant data and the references required for the successful

completion of the thesis

Last but not the least we would like to thank our parents for reposing so much faith

and care in us, giving us the financial and mental support to strive through and complete the

thesis.

Their constant encouragement and guidance provided us infinite motivation throughout

the thesis work.

Regards,

NAVEEN CHAKRAVARTHY

VIDYASAGAR

SRINIVAS KARNATI

ABSTRACT

For construction of approaches to flyovers and Road Over Bridge’s, Reinforced earth

technology has almost completely replaced conventional retaining structures. Geogrid

Reinforced earth wall retaining structures have gained wide acceptance in India as a

technically proven and cost effective alternative to conventional concrete retaining wall. The

ongoing and planned initiatives of central and state governments for improving the road

infrastructures in the country are likely to give a major boost for the demand for Geogrid

reinforced wall systems. Geosynthetics have become well established construction materials

for geotechnical and environmental applications in most parts of the world. Because they

constitute manufactured materials, new products and applications are developed on a routine

basis to provide solutions to routine and critical problems alike. Results from recent research

and from monitoring of instrumented structures throughout the years have led to new design

methods for different applications of geosynthetics.

Because of the significance of geosynthetic applications in segmental block reinforced

earthen wall construction, this paper focuses on the material specifications required for the

RE (reinforced earthen) wall, construction methodology adopted for construction of RE wall

and finally concluded with cost and time comparison between reinforced earthen wall and

retaining wall, taking a case study on reinforced earthen wall construction in outer ring road,

Hyderabad.

CONTENTS

SL.NO PARTICULARS PAGE NO

1. INTRODUCTION 1-7

1.1 General 1

1.2 Types of retaining structures 2

1.2.1 Gravity wall 2

1.2.2 Cantilevered wall 2

1.2.3 Sheet piling wall 3

1.2.4 Anchored wall 3

1.3 alternative retaining techniques 3

1.3.1 Soil nailing 3

1.3.2 Soil-strengthened 4

1.3.3 Gabion meshes 4

1.3.4 Mechanical stabilization 4

1.4 Objective of the study 5

1.5 Study area 6

1.5.1 Study area details 6

1.5.1.1 Site information 6

1.5.1.2 General climatic conditions 6

1.5.1.3 Seismic zone 6

1.6 Organization of the project report 7

2. LITERATURE REVIEW 8-15

3. MATERIAL SPECIFICATIONS 16-18

3.1 Materials used 16 3.1.1 Material specifications 16

3.1.2 Pre-cast concrete segmental block 16 3.1.3 Drainage aggregate 16

3.1.4 Drainage pipe 17

3.1.5 Geo grids 17

3.1.6 Geo textile 18

4. METHODOLOGY 19-24

4.1 construction methodology 19

4.1.1 Excavation and foundation preparation 19

4.1.2 Foundation levelling pad 19

4.1.3 Placement of first course of segmental blocks 20

4.1.4 Soil fill placement behind first course of blocks 20

4.1.5 Placement of first layer of geogrid reinforcement 20

4.1.6 Placement of soil fill above the geogrid 21

4.1.7 Placement of subsequent courses of blocks 21

4.1.8 Placement of geogrid reinforcement 21

4.2 Compaction of soil fill 22

4.2.1 Specifications 22

4.2.1.1 Reinforced soil fill 22

4.2.1.2 Retained soil fill 22

4.2.2 Procedure 23

4.2.3 Equipment used for compaction 23 4.3 placement of drainage system 24

4.4 coping beam 24

5. COST AND TIME ANALYSIS 25-30

5.1 Cost analysis of re wall & retaining wall 25

5.1.1 Retaining wall 25

5.1.1.1 Pcc cost 25

5.1.1.2 Raft cost 25

5.1.1.3 Wall cost 26

5.1.1.4 Steel cost 26

5.1.1.5 Total cost of retaining wall 26

5.1.2 Reinforced earthen wall 27

5.1.2.1 Reinforced earthen wall cost 27

5.2. Cost comparison of re wall & retaining wall 27

5.3 Chainages and locations of re walls in the site 28

5.4 Construction time cycle of 8m height re wall 30 5.5 Construction time cycle of 8m retaining wall 30

6. CONCLUSION 31

7. PHOTOS 32-39

8. REFERENCES 40

LIST OF TABLES

PARTICULARS PAGE NO

Table 3.1 Geogrid specifications 17

Table 3.2 Geogrid reinforcement properties 18

Table 3.3 Geotextile properties 18

Table 5.1 retaining wall pcc cost 25

Table 5.2 retaining wall raft cost 25

Table 5.3 retaining wall cost 26

Table 5.4 retaining wall steel cost 26

Table 5.5 retaining wall total cost 26

Table 5.6 reinforced earthen wall total cost 27

Table 5.7 cost comparison of re wall & retaining wall 27

LIST OF PHOTOS AND FIGURES

PARTICULARS PAGE NO

7.1. Concrete segmental block 32

7.2. Geo grid 33

7.3. Geo textile 34

7.4. Foundation and levelling pad 35

7.5. Blocks erection 35

7.6. Drainage material filling 36

7.7. Compaction of soil 36

7.8. Block dimensions 37

7.9. Levelling pad details 38

7.10. Connection between geogrid and blocks 38

7.11. Reinforcement details 39

7.12. Re wall sector wise details 39

1. INTRODUCTION

1.1 GENERAL

A retaining structure is used for maintaining the ground surface at different elevations on

either side of it. The material retained or supported by the structure is called backfill which

may have its top surface horizontal or inclined. The position of the back fill laying above a

horizontal plane at the elevation of the top of a wall is called the surcharge, and its

inclination to the horizontal is called surcharge angle “β”. Typically retaining walls are

cantilevered from a footing extending up beyond the grade on one side and retaining a higher

level grade on the opposite side. The walls must resist the lateral pressures generated by loose

soils or, in some cases, water pressures.

The most important consideration in proper design and installation of retaining walls is to

recognize and counteract the fact that the retained material is attempting to move forward and

down slope due to gravity. This creates lateral earth pressure behind the wall which depends

on the angle of internal friction (phi) and the cohesive strength (c) of the retained material, as

well as the direction and magnitude of movement the retaining structure undergoes.

Lateral earth pressures are typically smallest at the top of the wall and increase toward the

bottom. Earth pressures will push the wall forward or overturn it if not properly addressed.

Also, any groundwater behind the wall that is not dissipated by a drainage system causes an

additional horizontal hydrostatic pressure on the wall.

It is very important to have proper drainage behind the wall as it is critical to the

performance of retaining walls. Drainage materials will reduce or eliminate the hydrostatic

pressure and will therefore greatly improve the stability of the material behind the wall,

assuming that this is not a retaining wall for water.

1.2 TYPES OF RETAINING STRUCTURES:

1.2.1 GRAVITY WALL

Gravity walls depend on the weight of their mass (stone, concrete or other heavy material) to

resist pressures from behind and will often have a slight 'batter' setback, to improve stability

by leaning back into the retained soil. For short landscaping walls, they are often made from

mortar less stone or segmental concrete units (masonry units).

Earlier in the 20th century, taller retaining walls were often gravity walls made from large

masses of concrete or stone. Today, taller retaining walls are increasingly built as composite

gravity walls such as:

geo synthetic or with precast facing;

Gabions (stacked steel wire baskets filled with rocks);

Crib walls (cells built up log cabin style from precast concrete or timber and filled

with soil);

Soil-nailed walls (soil reinforced in place with steel and concrete rods).

1.2.2 CANTILEVERED WALL

Cantilevered retaining walls are made from an internal stem of steel-reinforced, cast-in-

place concrete or mortared masonry (often in the shape of an inverted T). These walls

cantilever loads (like a beam) to a large, structural footing, converting horizontal pressures

from behind the wall to vertical pressures on the ground below. Sometimes cantilevered walls

are buttressed on the front, or include a counter fort on the back, to improve their strength

resisting high loads. Buttresses are short wing walls at right angles to the main trend of the

wall. These walls require rigid concrete footings below seasonal frost depth. This type of wall

uses much less material than a traditional gravity wall.

1.2.3 SHEET PILING WALL

Sheet pile retaining walls are usually used in soft soils and tight spaces. Sheet pile walls are

made out of steel, vinyl or wood planks which are driven into the ground. For a quick

estimate the material is usually driven 1/3 above ground, 2/3 below ground, but this may be

altered depending on the environment. Taller sheet pile walls will need a tie-back anchor, or

"dead-man" placed in the soil a distance behind the face of the wall, that is tied to the wall,

usually by a cable or a rod. Anchors are placed behind the potential failure plane in the soil.

1.2.4 ANCHORED WALL

An anchored retaining wall can be constructed in any of the aforementioned styles but also

includes additional strength using cables or other stays anchored in the rock or soil behind it.

Usually driven into the material with boring, anchors are then expanded at the end of the

cable, either by mechanical means or often by injecting pressurized concrete, which expands

to form a bulb in the soil. Technically complex, this method is very useful where high loads

are expected, or where the wall itself has to be slender and would otherwise be too weak.

1.3 ALTERNATIVE RETAINING TECHNIQUES

1.3.1 SOIL NAILING

Soil nailing is a technique in which soil slopes, excavations or retaining walls are reinforced

by the insertion of relatively slender elements - normally steel reinforcing bars. The bars are

usually installed into a pre-drilled hole and then grouted into place or drilled and grouted

simultaneously. They are usually installed untensioned at a slight downward inclination. A

rigid or flexible facing (often sprayed concrete) or isolated soil nail heads may be used at the

surface.

1.3.2 SOIL-STRENGTHENED

A number of systems exist that do not simply consist of the wall itself, but reduce the earth

pressure acting on the wall itself. These are usually used in combination with one of the other

wall types, though some may only use it as facing (i.e. for visual purposes).

1.3.3 GABION MESHES

This type of soil strengthening, often also used without an outside wall, consists of wire mesh

'boxes' into which roughly cut stone or other material is filled. The mesh cages reduce some

internal movement/forces, and also reduce erosive forces.

1.3.4 MECHANICAL STABILIZATION

Mechanically stabilized earth, also called MSE, is soil constructed with artificial reinforcing

via layered horizontal mats (geosynthetics) fixed at their ends. These mats provide added

internal shear resistance beyond that of simple gravity wall structures. Other options include

steel straps, also layered. This type of soil strengthening usually needs outer facing walls

(S.R.W.'s - Segmental Retaining Walls) to affix the layers to and vice versa. The wall face is

often of precast concrete units that can tolerate some differential movement. The reinforced

soil's mass, along with the facing, then acts as an improved gravity wall. The reinforced mass

must be built large enough to retain the pressures from the soil behind it. Gravity walls

usually must be a minimum of 50 to 60 percent as deep or thick as the height of the wall, and

may have to be larger if there is a slope or surcharge on the wall.

1.4 OBJECTIVE OF THE STUDY

The main objective of the project is to study:

The material used for the reinforced earthen walls like segmental concrete blocks

geogrids, geopolmers, filter media, soil fill ,drainage fill, drainage pipes and its properties

as well as specification and equipments used for the constructional activities.

The construction methodology of the reinforced earthen wall.

Evaluation of the cost and time analysis for the retaining walls and re walls by

considering the present market prices of concrete, steel, formwork, labour, and comparing

the same.

Finally the study will be concluded by comparing RE wall and Reinforced earthen wall,

considering the factors like:

Time required for the construction

Cost of the work

Quality of work.

1.5 STUDY AREA

Hyderabad outer ring road, an 8lane express way was proposed to construct 162km.The main

purpose of the outer ring are as follows:

To reduce the traffic intensity in the city.

To develop the satellite townships by connecting the lands to the outer ring road

The four lane & two lane inner ring roads could not add up to resolve these problems. The

outer ring road construction included construction of carriage way of design speed of

120km/hr. it also included construction of vehicle underpass, pedestal under pass, minor

bridges, and box culverts, rotary junctions to avoid interruption of national highways, state

highway, and other state highway roads intersecting the express way.

HGC has adopted BOT & BOQ type of contract for different stretches based on the

feasibility. The study area of this thesis is a stretch between, Patancheru – Shamirpet from

km.23.700 to km.61.700 (Northern Arc) Package-I from Km 23.700 to Km 35.000

Patancheru-Mallampet on Build, Operate and Transfer (BOT) (Annuity) Basis. This BOT

contract was taken up by Ramky infrastructures.

1.5.1 STUDY AREA DETAILS

1.5.1.1 Site Information

The area in which the works are located is mostly plain to rolling terrain. The Project area is

located between 170 11/ 39

// - 17

0 36

/ 27.13

// N latitude and 78

0 14

/ 15

// - 78

0 41

/ 21

// E

longitude.

1.5.1.2 General Climatic Conditions

The variation in temperature in this region is between 100 C and 46

0 C.

The annual rainfall in the area is in the range of 790 mm to 1000 mm.

1.5.1.3 Seismic Zone

The works are located in seismic zone II as defined in IRC-6-2000

1.6 ORGANIZATION OF THE PROJECT REPORT

The first chapter deals with the importance of retaining structures, types of retaining

structures, and retaining techniques. It also covers the study area details, and the objective

of the study.

The second chapter covers review of literature, which focuses on the earlier works carried

out in the construction of RE wall using geogrids.

The third chapter deals with material specifications given for the construction of RE wall

using geopolymers and the photographs of the materials are also included in this chapter.

The fourth chapter contains the detailed construction methodology adopted for the

construction of RE wall using geogrids and the photographs of the approved drawings are

also included in this chapter.

In the fifth chapter contains the time and cost analysis between RE wall and retaining wall

construction.

The last chapter covers the results and conclusions drawn from the study carried out.

2. LITERATURE REVIEW

R.D. Nalawade and D.R. Nalawade (2008) in their paper “Stability and Cost Aspects of

Geogrid Reinforced Earth Wall of Flyover” made an attempt to compute the cost and

stability aspects of the reinforced earthen walls. For construction of approaches to flyovers

and Road Over Bridge’s, Reinforced earth technology has almost completely replaced

conventional retaining structures. Geogrid Reinforced earth wall retaining structures have

gained wide acceptance in India as a technically proven and cost effective alternative to

conventional concrete retaining wall. The ongoing and planned initiatives of central and state

governments for improving the road infrastructures in the country are likely to give a major

boost for the demand for Geogrid reinforced wall systems. In this paper methodological

design of retaining wall structure using geogrid for flyover near Agriculture College, Pune is

tackled through external, internal, wedge and seismic stability. Finally design by metallic

strips and Reinforced cement concrete cantilever retaining wall is carried out and the cost

comparison is made which shows Geogrid RE wall reduces the cost and time required for

construction.

SEIICHI ONODERA et al (2001) in their paper “Long-term durability of geogrids laid in

Reinforced soil wall” made an study on two types of 5m high geogrid reinforced soil walls

(gradient V:H=1:0.1) with two kinds of wall facing (wrapping type and L-shaped concrete

block type) trial soil walls were constructed in 1990, and an 8m high vertical reinforced soil

wall with concrete block wall facing and a 4.5m high reinforced soil wall (gradient

V:H=1:0.5) with a steel mesh frame as its wall facing trial soil walls were constructed in

1995. From the beginning of the construction stage, wall displacement or strain of the

geogrid, the earth pressure, etc. were measured for a long period of time. In 2002, when the

first walls were about 12 years old and the second walls were about 7 years old, parts of the

four kinds of geogrids that were used as the reinforcement of the embankment and as the wall

facing were sampled and underwent tensile tests to study their long-term durability. They

were also immersed in various chemicals for a long period time then underwent tensile test to

study their chemical degradation. The results confirmed that the geogrids buried in the soil

for 12 years or for 7 years retained their original tensile strength.

Xiao-jing Feng et al (2008) in their paper “The Influence of Facing Stiffness on the

Performance of Geogrid Reinforced Retaining Walls” stated that as pointed out by various

researchers, consideration of the influence of the facing type on reinforcement loads is

lacking in current limit equilibrium-based design methods for the internal stability design of

geosynthetic reinforced soil walls. Also the displacement of walls and the strain of

reinforcement are also related to the facing type. This paper reports the results of the three

instrumented model walls. The walls were nominally identical except one wall was

constructed with a rigid concrete block face, the other with a hinge joint wood face, and

another with a flexible wrapped face. The displacement of wall face added with the increase

of the stiffness of wall face under the same surcharge. The strain of the reinforcement was

influenced by the facing stiffness, while the relation between them also effected by the

loading type, backfill type etc. Under the strip load , the reinforcement strain in stiff-face wall

was higher. The ductile of the wall failure was reduced with the increasing of facing stiffness.

PETER JANOPAUL et al (1991) in their paper “Retaining Wall Construction And Block

Therefor” stated that in general, a block and retaining wall formed by a number of such

blocks are interconnected between courses by a plurality of Z shaped anchored elements

having an upper and lower body part of substantially rectangular cross-section.the upper body

part is offset from the lower body part. The offset of one course of blocks relative to the

course beneath will be a predetermined fixed amount determined by the offset of the body

parts of the interlocking Z-shaped anchor elements. A tie-back arrangement includes means

for attaching a sheet of geosynthetic material to the embedded end of a block so as to leave

the open cells within and those formed between the blocks unobstructed from the above and

available for filling with pea gravel or other drainage fill material.

Ennio M. Palmeira et al (2008) in their paper “Advances in Geo synthetics Materials and

Applications for Soil Reinforcement and Environmental Protection Works” explained

about the usage of geo synthetics materials in construction elements. Geosynthetics have been

increasingly used in geotechnical and environmental engineering for the last 4 decades. Over

the years, these products have helped designers and contractors to solve several types of

engineering problems where the use of conventional construction materials would be

restricted or considerably more expensive. There are a significant number of geosynthetic

types and geosynthetic applications in geotechnical and environmental engineering. Common

types of geosynthetics used for soil reinforcement include geotextiles (particularly woven

geotextiles), geogrids and geocells.

The sheets are flexible and permeable and generally have the appearance of a fabric.

Geogrids have a uniformly distributed array of apertures between their longitudinal and

transverse elements. These apertures allow direct contact between soil particles on either side

of the sheet. Geocells are relatively thick, three-dimensional networks constructed from strips

of polymeric sheet. The strips are joined together to form interconnected cells that are infilled

with soil and sometimes concrete. In some cases 0.5 m to 1 m wide strips of polyolefin

geogrids have been linked together with vertical polymeric rods used to form deep geocell

layers called geomattresses. soil confinement

(a) Geotextiles (b) Geogrids (c) Geocells

Geosynthetics commonly used for soil reinforcement (Bathurst 2007) A wide variety of

geosynthetics products can be used in environmental protection projects, including

geomembranes, geosynthetic clay liners (GCL), geonets, geocomposites and geopipes.

Geomembranes are continuous flexible sheets manufactured from one or more synthetic

materials. They are relatively impermeable and are used as liners for fluid or gas containment

and as vapour barriers. Geosynthetic clay liners (GCLs) are geocomposites that are

prefabricated with a bentonite clay layer typically incorporated between a top and bottom

geotextile layer or bonded to a geomembrane or single layer of geotextile. When hydrated

they are effective as a barrier for liquid or gas and are commonly used in landfill liner

applications often in conjunction with a geomembrane.

Geonets are open grid-like materials formed by two sets of coarse, parallel, extruded

polymeric strands intersecting at a constant acute angle. The network forms a sheet with in-

plane porosity that is used to carry relatively large fluid or gas flows. Geocomposites are

geosynthetics made from a combination of two or more geosynthetic types. Examples

include: geotextile-geonet; geotextile-geogrid; geonetgeomembrane; or a geosynthetic clay

liner (GCL). Geopipes are perforated or solid-wall polymeric pipes used for drainage of

liquids or gas (including leachate or gas collection in landfill applications). In some cases, the

perforated pipe is wrapped with a geotextile filter. Figure 2 presents schematically these

products. Because geosynthetics are manufactured materials, technological developments of

the polymer and engineering plastics industries have been continuously incorporated in

geosynthetics products, enhancing relevant engineering properties of these materials.

Research results have also lead to the development of new and more powerful design and

construction methods using geosynthetics. The combination of improved materials and design

methods has made possible engineers to face challenges and to build structures under

conditions that would be unthinkable in the past. This paper describes recent advances on

geosynthetics and on the applications of these materials in soil reinforcement and in

environmental protection projects.

DWIGHT A. BERANEK, P.E. (2002) in their paper “Use Of Geogrids In Pavement

Construction” focused how Engineers are continually faced with maintaining and

developing pavement infrastructure with limited financial resources. Traditional pavement

design and construction practices require high-quality materials for fulfillment of construction

standards. In many areas of the world, quality materials are unavailable or in short supply.

Due to these constraints, engineers are often forced to seek alternative designs using

substandard materials, commercial construction aids, and innovative design practices. One

category of commercial construction aids is geosynthetics. Geosynthetics include a large

variety of products composed of polymers and are designed to enhance geotechnical and

transportation projects. Geosynthetics perform at least one of five functions: separation,

reinforcement, filtration, drainage, and containment. One category of geosynthetics in

particular, geogrids, has gained increasing acceptance in road construction. Extensive

research programs have been conducted by the U.S. Army Engineer Research and

Development Center (ERDC) and non-military agencies to develop design and construction

guidance for the inclusion of geogrids in pavement systems.

A geogrid is defined as a geosynthetic material consisting of connected parallel sets of tensile

ribs with apertures of sufficient size to allow strike-through of surrounding soil, stone, or

other geotechnical material (Koerner 1998). Existing commercial geogrid products include

extruded geogrids, woven geogrids, welded geogrids, and geogrid composites. Extruded

geogrids are formed using a polymer sheet that is punched and drawn in either one or two

directions for improvement of engineering properties. Woven geogrids are manufactured by

weaving polymer fibers, typically polypropylene or polyester, that can be coated for increased

abrasion resistance (Berg et al. 2000). Welded geogrids are manufactured by welding the

junctions of woven segments of extruded polymers. Geogrid composites are formed when

geogrids are combined with other products to form a composite system capable of addressing

a particular application. Extruded geogrids have shown good performance when compared to

other types for pavement reinforcement applications (Cancelli et al. 1996, Miura et al. 1990,

and Webster 1993). Extruded geogrids can be divided into two broad categories based upon

their formation and principle application, uniaxial and biaxial. Extruded geogrids that are pre-

tensioned in one direction are called uniaxial geogrids and are typically used in geotechnical

engineering projects concerning reinforced earth and retaining walls. Extruded geogrids that

are pre-tensioned in two directions are referred to as biaxial geogrids and are typically used in

pavement applications where the direction of principle stress is uncertain. Most geogrids are

made from polymers, but some products have been manufactured from natural fibers, glass,

and metal strips. This document, however, will focus exclusively on polymer-based geogrids.

Ragui F. Wilson-Fahmy et al (1994) in their paper “Experimental Behavior of Polymeric

Geogrids in Pullout” stated that the increasing use of polymeric geogrids in reinforced soil

walls and steep slopes warrants special attention to all details including their

anchorage

behavior. Because of the open structural nature of geogrids, their performance is different

from other sheet-like reinforcing materials such as metallic strips and geotextiles. They derive

their anchorage capacity through both friction and bearing resistances. This paper focuses on

the structural behavior of geogrids under a pullout loading condition. An experimental

investigation is conducted using three different geogrids tested at three different lengths. The

load-displacement response at different locations along the geogrid is monitored during

pullout. The experimental results are compared with predictions using a previously published

finite-element model

simulating soil-geogrid interaction and taking into account the

deformation of the geogrid structure. Tension in the geogrid, as well as

friction and bearing

components of resistance, are presented in relation to geogrid length, pullout load magnitude,

and distance from the clamped end of the geogrid. Factors such as the load-extension

behavior

of ribs in the pullout load direction and the flexibility of ribs in the perpendicular direction as

well as their ability to transfer the load through the rib junctions

are shown to greatly

influence the overall behavior. The results emphasize the fact that the success of a geogrid in

fulfilling its anchorage role is directly related to its structural composition and material

specific characteristics.

Han Yong Jeon et al (2002) in their paper “Assessment of long-term performances of

polyester geogrids by accelerated creep test “ viewed that Geogrids are widely used as the

reinforcement materials in geotechnical and civil engineering fields. In this study,

accelerated-creep tests at elevated temperatures to predict longer-term creep behavior of

polyester fabric geogrids were examined using the time–temperature superposition principle.

Creep tests were generally performed to calculate the partial factor of safety during the

service time of polyester geogrids and two types of geogrids, having different design

strengths ranging from 8 to 15 t/m, were used in this study. The creep tests were carried out at

various temperatures and loading levels of 40, 50, and 60% of short-term design strengths.

Also, the creep tests were made at temperatures between 20 and 50°C to take into

consideration the real environmental conditions of geogrids. The results indicated the

applicability of the conventional procedures in prediction of longer time creep strain and

material dependency of creep strains.

P. Bataille et al (2004) et al in their paper “Mechanical properties and permeability of

polypropylene and poly (ethylene terephthalate) mixtures” studied that the synthetic

membranes currently used for soil stabilization and road construction are mainly made of

polypropylene and of polyesters. They are used separately for each application. The polymer

used has an effect on the wettability and, the permeability of the membrane. The

polypropylene membranes, for instance, have a zero wettability, whereas it is high for

polyester membranes. This paper reports on the mechanical properties and the permeability of

mixtures of polypropylene (PP) and poly(ethylene terephthalate) (PET). The elastic modulus

of the mixture was at a minimum for a 50/50 mixture. For the other compositions, the moduli

gave a positive deviation as compared with the additivity equation results. This is probably

due to the fact that pure PET has a fragile behavior at the temperature at which the

mechanical tests were run. This 50/50 composition corresponds to the domain where a phase

inversion occurs. The permeability to water vapor gave an S-shape curve that is typical of a

“mixture” of immiscible polymers. The diffusion of the water molecules is controlled by the

continuous phase. To compatibilize the two homopolymers, a 94/6 copolymer of PP and of

polyacrylic acid was added, at various levels, to a 60/40 mixture of PET and PP: This did not

affect markedly the elastic modulus. The yield stress increased, however, indicating that we

had a better adhesion and that the copolymer seems to have a certain emulsifier effect,

increasing the quality of the dispersion.

J. Engrg. Mech.(2004) in his paper “Analyzing Dynamic Behavior of Geosynthetic-

Reinforced Soil Retaining Walls” stated that an advanced generalized plasticity soil model

and bounding surface geosynthetic model, in conjunction with a dynamic finite element

procedure, are used to analyze the behavior of geosynthetic-reinforced soil retaining walls.

The construction behavior of a full-scale wall is first analyzed followed

by a series of five

shaking table tests conducted in a centrifuge. The parameters for the sandy backfill soils are

calibrated through the results of monotonic and cyclic triaxial tests.

The wall facing

deformations, strains in the geogrid reinforcement layers, lateral earth pressures acting at the

facing blocks, and vertical stresses at the foundation are presented. In the centrifugal shaking

table tests, the response of the walls subject to 20 cycles of sinusoidal wave having a

frequency of 2 Hz and of acceleration amplitude of 0.2g are compared with the

results of

analysis. The acceleration in the backfill, strain in the geogrid layers, and facing deformation

are computed and compared to the test results. The results of analysis for both

static and

dynamic tests compared reasonably well with the experimental results.

3. MATERIAL SPECIFICATIONS

3.1 MATERIALS USED:

SEGMENTAL BLOCKS

DRAINAGE AGGREGATE

DRAINAGE PIPE

GEOGRIDS

GEOTEXTILE

3.1.1 MATERIAL SPECIFICATIONS

3.1.2 PRE-CAST CONCRETE SEGMENTAL BLOCKS

The dimensions of segmental units are shown on the approved drawings

(fig 1,pg no;32)

The units have a minimum 28 days compressive strength of 35MPa. .

The blocks are manufactured by automatic block –making machine ensuring

consistent quality of concrete, accuracy of dimensions and good finish.

The blocks are cured for a sufficient length of time as approved by the engineer using

potable water. Sufficient care was taken to ensure that blocks are not damaged during

handling, storage and transportation.

One sample of six cubes is taken from each lot of 5 cum or part thereof produced per

day.

Of these 3 cubes are cured and the blocks are tested to determine when the units are to

be placed in the structure.

Units are acceptable for placement in the structure if the strength at 7 days or before

exceeds 75% of the 28 days requirement.

3.1.3 DRAINAGE AGGREGATE

The drainage material is a cleaned crushed stone or gravel with particle size in the

range of 9.5-19.1mm and % fines <5% or a suitable material.

3.1.4 DRAINAGE PIPE

The drainage collection pipe is perforated or slotted PVC of 150mm diameter.

3.1.5 GEO GRIDS

Geogrids used as soil reinforcement should be GX polyester geogrids of style GX 40/40,GX 60/30,

GX 80/30, GX 100/30, GX130/30, and GX 160/50 with the following specifications.

Polymer High strength polymers yarns

Coating Black PVC

Property Test methods Unit GX40 GX60 GX 80 GX100 GX 130 GX 160

Ultimate

tensile

strength(MD)

ASTM

D4595

kN/m

40

60

80

100

130

160

Ultimate

tensile

strength(TD)

kN/m

40

30

30

30

30

30

Elongation at

break(MD)

%

<11%

<11%

<11%

<11%

<11%

<11%

Creep reduced

strength 120

years

kN/m

27

41

55

68

89

110

Long term

design

strength(LTSD)

21

34

46

58

75

92

-

Table 3.1 Geogrid Specifications

The type, length and placement location for the geogrid is as shown on approved construction

drawings

Table 3.2 Geogrid Reinforcement Properties

REINFORCEMENT PROPERTIES

GEOGRID

TYPE

TULT(KN) FCR Fext. Finst Fenv Ftot TD(KN)

GX 40 40 145 1 1.21 1.1 1.936 20.7

GX 60 60 145 1 1.19 1.1 1.898 31.6

GX 80 80 145 1 1.17 1.1 1.866 42.9

GX 100 100 145 1 1.14 1.1 1.818 55.8

GX 130 130 145 1 1.11 1.1 1.770 73.4

GX 160 160 145 1 1.11 1.1 1.770 90.4

GX 200 200 145 1 1.11 1.1 1.770 113.0

3.1.6 GEOTEXTILE

The geotextile used as filter for the granular drainage bay is meeting the requirements of

MORTH specifications for Road and Bridge works, Clause 702.2.3.

The geotextile used are meeting the following minimum requirements in terms of minimum

average roll values.

Roll width m 5 5 5 5 5 5

Roll length m 50 50 50 50 50 50

Table 3.3 Geotextile Properties

Property Test method MARV Value

Mass per unit area ASTM D 5261 155 g/ sq.m

Thickness 2k Pa ASTM D 5199 1.5mm

Grab tensile strength md ASTM D 4632 690 N

Elongation at break md 75 %

Wide width tensile strength. (ave) ASTM D 4595 11.5 kN/m

Elongation at break. md ASTM D 4595 75%

CBR Puncture strength ISO 12236 1750

Apparent opening size (095) ASTM D 4751 0.25 mm

Rod Puncture strength ASTM D 4833 310 N

Permittivity ASTM D 4491 2.71/s

4. METHODOLOGY

4.1 CONSTRUCTION METHODOLOGY

4.1.1 EXCAVATION AND FOUNDATION PREPARATION

The site is excavated to the lines, width and grades as shown in the approved

construction drawings.

The trench for the leveling pad is excavated to the correct depth and width.

In the reinforced soil zone the ground is excavated to a depth of 200mm (minimum)

below the first layer of geogrid reinforcement.

Any unsuitable soils if present is removed and replaced by compacted fill, similarly

pits, depressions etc. is filled by compacted fill of approved quality.

4.1.2 FOUNDATION LEVELLING PAD

The centerline for the leveling pad is marked on the bottom of the trench ensuring

required setback to accommodate the facing batter as shown on the construction

drawings (fig 4 pg no:35)and the side forms are fixed for the leveling pad.

The leveling pad consists of a plain cement concrete strip footing of 600 mm width

and 200 mm thickness.

Concrete has a minimum grade of M 15 and maximum size of aggregates limited to

20 mm.

Concrete is poured (minimum grade of M15), and compacted using needle vibrators,

and screed to the correct level and finished using a wooden floats to flat and smooth

finish.

The leveling pad is casted with a level tolerance of a 5mm and the surface is finished

using a smooth wood float.

The leveling pad is cured for a minimum period of 48 hours before erection of

segmental units is commenced.

4.1.3 PLACEMENT OF FIRST COURSE OF SEGMENTAL BOLCKS

The first course of segmental block is placed to the correct line as marked on the

leveling pad as shown in (fig 4,pg no:35)

A thin layer of stiff cement mortar is provided on top of leveling pad, to ensure

accurate placing of leveling blocks.

The next extremely important step is to place the first course of blocks to the correct

line and level.

Drainage aggregate is then placed and lightly compacted to fill openings between

segmental units.

4.1.4 SOIL FILL PLACEMENT BEHIND FIRST COURSE OF SEGMENTAL

BLOCKS

Soil fill is Placed and compacted behind the segmental units and drainage material is

in filled up to the height of the block as shown in (fig 5, pg no35)

4.1.5 PLACEMENT OF FIRST LAYER OF GEOGRID REINFORCEMENT

After ensuring the drainage infill between the blocks and soil fill is level with or

slightly above the top of the segmental unit, the debris is cleaned off from the top of

the segmental units as shown in( fig 5, pg no;35).

Position geogrid of the required type and length is positioned as shown on drawings

with the longitudinal direction perpendicular to wall face.

Adjacent roll of geogrid is placed such that they are butting each other.

Next course of segmental unit is placed in a running bond configuration.

Segmental unit is moved forward to engage shear key and ensuring proper alignment

and set back of the segmental units

4.1.6 PLACEMENT OF SOIL FILL ABOVE THE GEOGRID

Geogrid is pulled taut using uniform tension, hold or stake to maintain tension

throughout the soil fill placement process as shown in (fig7,pg no:.36)

Drainage infill and soil fill is placed on the openings between segmental units and

then the soil fill and drainage in-fill is compacted.

4.1.7 PLACEMENT OF SUBSEQUENT COURSES OF SEGMENTAL BLOCK

UNITS

Segmental blocks are placed in a running bond configuration. (fig 5,pg no:35)

Care is taken to clean the top surface of the blocks with a stiff brush or broom to

remove any soil fill, drainage aggregate etc., before placing the subsequent course of

blocks.

At each level, blocks are properly aligned and pushed forward to engage the shear key

to ensure proper set back.

Drainage aggregate is placed and lightly compacted to fill openings between

segmental units.

4.1.8 PLACEMENT OF GEOGRID REINFORCEMENT

Geogrid of the required type and length is placed at elevations as shown on the

drawings (fig5 in pg no:35)

Geogrid is placed with the machine direction perpendicular to the wall face.

Adjacent rolls is placed butting against each other.

No joints are permitted in the geogrid in the longitudinal direction.

Geogrid is placed in between the segmental units with the required embedment to

develop required connection strength.

Soil fill and drainage placed behind the facing is ensured that there is no a void or

cavities below the geogrid.

The geogrid is pulled taught and held with small tension during soil fill placement

until the weight of soil fill is adequate to keep the geogrid taught.

At the same time it is ensured that, excessive tension is not applied to geogrid, which

may lead to misalignment of blocks.

4.2 COMPACTION OF SOIL FILL

4.2.1 SPECIFICATIONS

4.2.1.1 REINFORCED SOIL FILL

The reinforced soil fill selected is a granular fill with the following properties.

Peak effective angle of shearing resistance 320

% fines (passing 75 micron sieve) 15%

The dry density of the compacted fill is at least equal to the following minimum

requirements:

The soil fill (except in the following case) shall be compacted to 95% of the maximum

laboratory density measured as per IS 2720(part 8).

Fill within 1 m depth below the road crust should be compacted to 97% of maximum

laboratory density.

4.2.1.2 RETAINED SOIL FILL

The retained soil fill is having a minimum peak effective angle of shearing resistance of 320.

The dry density of the compacted fill is at least equal to the following minimum

requirements.

The soil fill (except in the following case) shall be compacted to 95% of the maximum

laboratory density measured as per IS 2720(part 8).

Fill within 1 m depth below the road crust should be compacted to 97% of maximum

laboratory density

4.2.2 PROCEDURE

The deposition, spreading, leveling and compaction of the soil fill is carried out in a

direction parallel to the facing.

No plant or equipment with a weight exceeding 1500 kg is allowed to operate within

1.5m from the facing.

Construction equipment is allowed to move directly over the geogrid, ensuring that

there is a minimum soil cover of 100 mm over the strips.

Abrupt stopping, turning etc. of the equipment is avoided to minimize misalignment

of geogrids.

Care is taken during the deposition, spreading, leveling and compaction of the soil fill

to avoid damage, disturbance or misalignment of segmental blocks, geotextile filter

and geogrid reinforcement.

Soil fill placed near the facing is ensured, that no voids exist directly below the

geogrid reinforcement. As shown in (fig 7, pg no:36)

Soil fill is placed and compacted in lifts. Thickness of lift is consistent with the

compaction equipment used and the degree of compaction to be achieved.

If necessary water is sprinkled to bring the water content close to the OMC.

4.2.3 EQUIPMENT USED FOR COMPACTION

Compaction of the soil fill is carried out using appropriate equipment, which will not induce

excessive loads on the facing and at the same time achieves the required compaction.

Towards this the following equipments are recommended for different zones:

Within 300 mm of the facing, the soil fill/drainage material is compacted by a light-

weight plate compactor or by hand tamping.

Beyond 300 mm and within 1.5 m from the facing the soil fill is compacted using a

walk behind vibratory roller or plate compactor with a total weight less than 1500 kg.

Beyond a distance of 1.5 m from the facing, the soil fill is compacted using

appropriate rollers of 8-10 MT weight.

Movement of compaction equipment is in a direction parallel to the wall face, starting

near the face and gradually moving away from the wall face.

4.3 PLACEMENT OF DRAINAGE SYSTEM

Drainage material is placed to the minimum finished thickness as shown on the

construction drawings.

During placement and compaction of drainage material, care is taken to ensure that

there is no contamination with undesirable materials.

Vertical layers of drainage layer material are brought up at the same rate as the

adjoining fill material.

Geotextile filter is provided behind the drainage bay and is wrapped back into the soil

fill with a minimum wrap length of 200 mm.

Perforated collection pipe wrapped with geotextile filter is installed at the location as

shown on the drawings. Discharge exits are provided at required intervals.

4.4 COPING BEAM

On the topmost segmental unit, erect form work and cast coping beam to get the required

longitudinal profile of the wall.

5. COST AND TIME ANALYSIS

5.1 COST ANALYSIS OF RE WALL & RETAINING WALL:

5.1.1 RETAINING WALL:

Pcc cost per cubic meter is 2600 Rs. (pcc cost includes cost of m15 concrete, labour,

shuttering.)

Raft cost per cubic meter is 2150 Rs. (Raft cost includes cost of m30 concrete, labour,

shuttering, and equipment.)

Wall cost per cubic meter is 3900 Rs. (Wall cost includes cost of m30 concrete, labour,

shuttering, and equipment.)

Steel binding cost per metric ton is 3500 Rs. (Steel cost includes cost of labour, cutting and

binding.)

Steel cost per metric ton is 38000 Rs.

5.1.1.1 PCC COST:

Table 5.1 retaining wall pcc cost

5.1.1.2 RAFT COST:

Table 5.2 retaining wall raft cost

HEIGHT OF WALL

WIDTH LENGTH THICKNESS QUANTITY COST TOTALCOST

4 6.250 20 0.450 56.250 2150.000 120937.500

5 7.813 20 0.563 87.891 2150.000 188964.844

6 9.375 20 0.675 2150.000 2150.000 272109.375

HEIGHT OF WALL(M)

WIDTH (M)

LENGTH (M)

THICKNESS (M)

QUANTITY (CUM)

COST (RS)

TOTALCOST (RS)

4 6.250 20 0.150 18.750 2600.000 48750.000

5 7.813 20 0.150 23.438 2600.000 60937.500

6 9.375 20 0.150 28.125 2600.000 73125.000

7 10.938 20 0.150 32.813 2600.000 85312.500

8 12.500 20 0.150 37.500 2600.000 97500.000

7 10.938 20 0.788 172.266 2150.000 370371.094

8 12.500 20 0.900 225.000

483750.000

5.1.1.3 WALL COST:

Table 5.3 retaining wall cost

HEIGHT OF WALL HIGHT LEGTH THICKNESS QUANTITY COST

TOTAL COST

4 4 20 0.475 38.000 3900.000 148200.00

5 5 20 0.594 59.375 3900.000 231562.50

6 6 20 0.713 85.500 3900.000 333450.00

7 7 20 0.831 116.375 3900.000 453862.50

8 8 20 0.950 152.000 3900.000 592800.00

5.1.1.4 STEEL COST:

Table 5.4 retaining wall steel cost

HEIGHT

OF WALL(M)

LENGTH

OF WALL(M)

COST OF CONCRETE (RS) STEEL COST

(RS)

(4)

TOTAL

COST(RS)

(1+2+3+4)

PCC

(1)

RAFT

(2)

WALL

(3)

4 20 48750.000 120937.500 148200.000 379725.000 697612.500

5 20 60937.500 188964.844 231562.500 474656.250 529121.094

6 20 73125.000 272109.375 333450.000 569587.500 1248271.875

7 20 85312.500 370371.094 453862.500 664518.750 1574064.844

8 20 97500.000 483750.000 592800.000 759450.000 1933500.000

5.1.1.5 TOTAL COST OF RETAINING WALL:

Table 5.5 retaining wall total cost

5.1.2 REINFORCED EARTHEN WALL: ERECTION COST INCLUDES COST OF GEO GRID, GEO TEXTILE, AGREGATE, LABOUR & EQUIPMENT COST. SEGMENTAL BLOCK COST IS 150 RS.INCLUDES DRAINAGE MATERIAL.

5.1.2.1 REINFORCED EARTHN WALL COST:

HEIGHT OF WALL(M) STEEL REQUIRED(MT) COST/TON(RS) TOTAL COST(RS)

4 9.150 41500 379725.000

5 11.438 41500 474656.250

6 13.725 41500 569587.500

7 16.013 41500 664518.750

8 18.300 41500 759450.000

HEIGHT OF WALL(M)

ERECTION COST/SQM(RS)

UP TO 6 1928

7 2014

8 2185

HEIGHT OF WALL(M) LENGTH(M) SQM BLOCKS/SQM(N) TOTAL BLOCKS(N)

4 20 80 11.11 888.800

5 20 100 11.11 1111.000

6 20 120 11.11 1333.200

7 20 140 11.11 1555.400

8 20 160 11.11 1777.600

Table 5.6 reinforced earthen wall total cost

5.2. COST COMPARISON OF RE WALL & RETAINING WALL:

HEIGHT OF WALL(M)

COST OF BLOCK (RS)

TOTAL BLOCKS

COST(RS)(1) SQM

ERECTION COST/SQM

TOTAL ERECTION

COST(RS)(2)

COST OF RE WALL(RS)

(1+2)

4 150 133320.000 80 1928 154240 287560.000

5 150 166650.000 100 1928 192800 359450.000

6 150 199980.000 120 1928 231360 431340.000

7 150 233310.000 140 2014 281960 515270.000

8 150 266640.000 160 2185 349600 616240.000

HEIGHT OF RE WALL & RETAININGWALL(M)

LENGTH OF RE WALL & RETAININGWALL(M)

RETAINING WALL COST(RS)

RE WALL COST(RS)

4 20 697612.500 287560.000

5 20 529121.094 359450.000

6 20 1248271.875 431340.000

7 20 1574064.844 515270.000

8 20 1933500.000 616240.000

5.3 CHAINAGES AND LOCATIONS OF RE WALLS IN THE SITE:

RETAINING WALL TOTAL LENGTH = 4154.9M

REINFORCED EARTH WALL TOTAL LENGTH = 1997.505M

SI.NO CHAINAGE LENGTH DECRIPTION REMARKS

FROME TO

1 24.240 25.325 1085.00 RETENING WALL

2 25.325 25.409 84.00 RE WALL VUP LOCATIONS

3 25.409 25.570 161.00 RE WALL

4 25.570 25.680 110.00 RE WALL

5 25.699 25.750 50.50 RE WALL

6 25.750 25.850 100.00 RETENING WALL

7 26.600 26.850 250.00 RETENING WALL

8 26.850 26.858 8.00 RETENING WALL

9 26.858 26.942 84.00 RE WALL VUP LOCATIONS

10 26.942 27.220 278.00 RETENING WALL

11 28.560 28.820 260.00 RETENING WALL

12 28.820 28.930 110.00 RE WALL

13 28.949 29.088 139.00 RE WALL

14 29.088 29.172 84.00 RE WALL VUP LOCATIONS

15 29.172 29.670 498.00 RE WALL

16 29.920 30.420 500.65 RETENING WALL

17 30.420 31.410 990.00 DECISION PENDING

18 30.439 30.900 460.38 RE WALL

19 31.460 31.680 220.00 RETENING WALL

20 32.070 32.480 410.00 RETENING WALL

21 32.480 32.488 8.00 RETENING WALL

22 32.488 32.572 84.00 RE WALL VUP LOCATIONS

23 32.572 32.580 8.00 RETENING WALL

24 32.580 32.760 180.00 RETENING WALL

25 33.020 33.430 410.00 DECISION PENDING

26 34.170 34.390 220.625 RETENING WALL

27 34.409 34.458 48.625 RE WALL VUP LOCATIONS

28 34.458 34.542 84.00 RE WALL

6. CONCLUSION

Materials used for construction of reinforced earthen walls were geogrids, geotextile,

drainage aggregate, drainage pipe, and segmental blocks

For the construction of reinforced earthen walls there is no need of deep foundations (pcc,

reinforcement, raft,).It involves the process like casting of foundation leveling pad, erection

of facing units, placement and compaction of soil fill to the first layer of reinforcement,

placement of the first layer of geogrid reinforcements, placement of next and subsequent lifts

of soil fill, erection of subsequent rows of facing units and reinforcements, coping.

The cost for the construction of reinforced earthen walls is nearly 30% of the cost of retaining

wall.

The time required for construction of reinforced earthen walls is more when compared to the

construction of retaining walls. We can construct a retaining wall of height 1.2m in a day, and

the entire process like (deshutteing, reinforcement binding, shuttering for additional height)

takes 3-4 days, where as for the reinforced earthen wall, the construction is done in layers,

and each layer of 200mm was filled and compacted up to 98% MDD, so on an average it

takes a week days for 0.6 m height. So we can conclude that, the retaining wall can be

preferred if the height of the wall is less than 4m, and if the height is more than 4m reinforced

earthen walls can be preferred due to their stability, and also its capacity to reduce the future

settlement of pavement by controlling the erosion of soil fill with the help of geotextile

placed between the soil fill and drainage aggregate.

The workers/ labor required for the construction of retaining wall is more compared to

reinforced earthen wall , 7-9 workers are required for the construction of retaining wall,

where as for the construction of reinforced earthen wall, the blocks are casted by the machine

and only 2 or 3 workers are required for the placing and finishing of blocks

7. PHOTOS

7.1. Concrete segmental block:

Figure 1

7.2. Geo grid:

Figure 2

7.3. Geo textile:

Figure 3

7.4. Foundation and levelling pad:

Figure 4

7.5. Blocks Erection:

Figure 5

7.6. Drainage material filling:

Figure 6

7.7. Compaction of soil:

Figure 7

7.8. Block dimensions:

Figure 8

7.9. Levelling pad details:

Figure 9

7.10. Connection between geogrid and segmental blocks:

7.11. Reinforcement details:

Figure 11

7.12. Re wall sector wise details:

8. REFERENCES

1. R.D. Nalawade and D.R. Nalawade (2008): “Stability and Cost Aspects of Geogrid

Reinforced Earth Wall of Flyover”

2. SEIICHI ONODERA et al (2001): “Long-term durability of geogrids laid in

Reinforced soil wall”

3. Xiao-jing Feng et al (2008): “The Influence of Facing Stiffness on the Performance of

Geogrid Reinforced Retaining Walls” stated that as pointed out by

4. PETER JANOPAUL et al (1991): “Retaining Wall Construction And Block

There for”

5. Ennio M. Palmeira et al (2008): “Advances in Geo synthetics Materials and

Applications for Soil Reinforcement and Environmental Protection Works”

6. DWIGHT A. BERANEK, P.E. (2002): “Use of Geogrids In Pavement Construction”

7. Ragui F. Wilson-Fahmy et al (1994): “Experimental Behavior of Polymeric

Geogrids in Pullout”

8. Han Yong Jeon et al (2002): “Assessment of long-term performances of

polyester geogrids by accelerated creep test”

9. P. Bataille et al (2004): “Mechanical properties and permeability of polypropylene and

poly (ethylene terephthalate) mixtures”

10. J. Engrg. Mech. (2004): “Analyzing Dynamic Behavior of Geosynthetic-

Reinforced Soil Retaining Walls”

11. “Design and Construction of reinforced earthen wall”- GEOSOL ASSOCIATES.