Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
1
G&P Geotechnics Sdn Bhd (G&P Geotechnics Sdn Bhd (www.gnpgroup.com.mywww.gnpgroup.com.my))
By Ir. Dr. Gue See Sew & Ir. Chow Chee Menghttp://www.gnpgeo.com.my
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
CONTENTSCONTENTS• INTRODUCTION• OBJECTIVES• DESK STUDY• SITE RECONNAISSANCE• METHODS OF GROUND INVESTIGATION• FIELD TEST AND SAMPLING• PLANNING OF GROUND INVESTIGATION• SPECIFICATIONS• SUPERVISION
2
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
INTRODUCTIONINTRODUCTION
Guidance notes to engineers on the practical aspect of site investigation
3
4
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
OBJECTIVESOBJECTIVESProvide adequate information for
- Site assessment, safe and economical designs of temporary and permanent works.
- Planning and assessment of construction method.
- Foresee construction difficulties.- Choice of site and layout
arrangement.
5
DESK STUDYDESK STUDY
Topographic Maps
Geological Maps & MemoirsSite Histories &
Landuse
Results of Adjacent &
Nearby Ground Investigation
Aerial Photographs
Details of Adjacent
Structures & Foundation
Topographic Map
6
Geological MapGeological Map
Aerial PhotographsAerial Photographs
7
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
1981..
Proposed Development
Aerial Photograph (22 years ago)Aerial Photograph (22 years ago)
8
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Proposed Development
1985..
Aerial Photograph (18 years ago)Aerial Photograph (18 years ago)
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Aerial Photograph (4 years ago)Aerial Photograph (4 years ago)
Proposed Development
1999..Residential
Residential
Residential
9
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Aerial Photo Aerial Photo (2006)(2006)
60% of the site were located at sea
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Aerial Photo Aerial Photo (2008)(2008)
Earthworks in progress to form the site profile.
10
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Aerial Photo Aerial Photo (2009)(2009)
Reclamation Done
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Aerial Photo Aerial Photo (2011)(2011)
Current Site Profile Formed
11
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
SITE RECONNAISSANCESITE RECONNAISSANCE• Confirm and obtain additional
information.• Examine adjacent and nearby
development.• Compare the surface features and
topography with data obtainable in the desk study.
• Locate and study the outcrops, previous slips.
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Exposed Pile
Settlement
Settling Platform Detached from Building
12
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
13
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Vegetation
14
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Vegetation
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Vegetation at Site (Wall Failure Area)
15
G&P Geotechnics Sdn Bhd (G&P Geotechnics Sdn Bhd (www.gnpgroup.com.mywww.gnpgroup.com.my))
METHODS OF GROUND METHODS OF GROUND INVESTIGATIONINVESTIGATION
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
• Light Dynamic Penetrometer and Hand Auger
• Excavation and Borehole- Trial Pits- Sampling of soil and rock- Groundwater monitoring via Piezometer- SPT - Vane shear test
• Piezocone• Geophysical
16
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
LIGHT DYNAMIC PENETROMETERLIGHT DYNAMIC PENETROMETER
• JKR or Mackintosh probe- to obtain preliminary subsoil information.- limit to shallow depth.- drop of hammer should be free fall and
consistent drop height.
17
JKR OR MACKINTOSH PROBES
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
HAND AUGERHAND AUGER
- To determine soil type and ground water.- Depth ≤ 5m
18
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
EXCAVATIONEXCAVATION• To prospect fill materials or exposing
materials.• Only apply to shallow depth (≤ 5m)
- Safety Precautions
• Stability of sides / slopes• Barricades if the pit is needed for further
testing• Backfill and compact properly after use.
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
BOREHOLESBOREHOLES• Refer to BS 5930• Includes boring, sampling, in-situ testing
and water table observation.• Drill through soils and core through
rocks.• Two commonly used methods:
a) Rotary drilling methodb) Wash boring
• Rock Coring
19
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Care in Boreholes
- levels and coordinates
- Samplers in good condition, clean & greased
- Samplers sealed, labelled & stored
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
20
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Sizes of commonlySizes of commonly--used Core barrels, Casings and Drill used Core barrels, Casings and Drill Rods UsedRods Used
21
Typical Rotary Drilling RigTypical Rotary Drilling Rig
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Sampling in BoreholesSampling in Boreholes• Wash Samples
- soil strata description
• Disturbed Samples- Split spoon samples from SPT
• Undisturbed Samples- Piston Sampler- Thin wall sampler- Continuous Sampler- Mazier Sampler
22
Piston SamplerPiston Sampler
- for very soft to soft cohesive soils with (SPT’ N’ < 2)
Thin Wall SamplerThin Wall Sampler
- for cohesive soils up to firm consistency (SPT’N’ < 10)
23
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Continuous SamplerContinuous Sampler
• To identify sand lenses, description and classification tests.
• Usually for soft marine deposits.
MazierMazier SamplerSampler- Three-tube core-barrels containing detachable liners within the inner barrel.
- Suitable for stiffer soil stratum.
24
Care in SamplingCare in Sampling
Staging for Borehole at Mud Flats
25
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Sg. Kelang
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Groundwater Groundwater • Water level should be taken daily during SI
(particularly in the morning).
• Piezometer should be used for accurate and longer time measurement.
• Good practice :1. Lower down water level in borehole 2. Allow the ground water rise to original
level 3. Collect the water samples.
26
Boreholes with Standpipe
Piezometers Lockable Cap to prevent vandalism
Bright Color (Red + White) to prevent vehicle knocking into it.
Borehole Number Clearly Marked on
Concrete
27
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Standard Penetration Test (SPT)Standard Penetration Test (SPT)
• According to BS 1377
- Hammer weight = 63.5kg- Drop height = 760mm- Total penetration is 450mm and the
number of blows for the last 300mm is the SPT’ N’ value.
Care - depth of test vs casing L
*site supervision
Equipment for SPT
28
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
ERRORS CONSEQUENCE
Inadequate cleaning of borehole (X) N, sludge trapped in sampler Casing driven bottom of the borehole )(↑ N in sand & )(↓ N in clay Damaged tip of sampling spoons )(↑ N Loose joints on connecting rods )(↑ N Not using guide rod )(↑ N, eccentric blows Water level in borehole below ground water level
)(↓ N especially sand at bottom of borehole, piping effect
Note : Where N = SPT’N’ values, )(↓ = Giving misleading lower value, )(↑ = Giving misleading higher value, (X) = Wrong Results
Factors Affecting SPT (N) Factors Affecting SPT (N) ValuesValues
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Field Vane Shear TestField Vane Shear Test
• To obtain in-situ undrained shear strength of very soft to firm clay (clay only).
• Standard rate of rotation:- 6 degrees or 12 degree per minute
• Sensitivity of the soil can be determined
• Correct calibration chart for the torque shall be used.
• Influence of rootlets and coarse particles may lead to misleading results.
29
Field Vane Shear DevicesField Vane Shear Devices
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
PiezoconePiezocone (CPTU)(CPTU)• Advanced static cone penetration
test.• Rapid and continuous measures of
soil profile ,strength and pore water pressure.
• Allow dissipation test and obtain consolidation parameters.
• Data are captured electronically on computer.
30
Detailed Terminology of Piezocone Typical Piezocone Rig
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
31
PiezoconePiezocone
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
PLANNING OF GROUND PLANNING OF GROUND INVESTIGATIONINVESTIGATION
32
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Stage 1 Stage 1 -- PreliminaryPreliminary• General subsoil profile
- Estimate earthwork and rock excavation- Typical soft areas, cut or fill.
• Preliminary confirmation of layout and formation levels.
• Preliminary soil parameters and water table.
• Conceptual design and preliminary cost estimation.
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
?
?
?
?
?
??
?? ?
?
Ground Conditions?
SHIFT
Limestone
33
S.I. In Grid PatternS.I. In Grid Pattern
(Total = 32 nos)
Not Recommended
Proposed SIProposed SI
(Total = 32 nos)
34
Typical CrossTypical Cross--SectionSection
Ground Level
Bedrock LevelVery Hard Material Level
Hard Material Level
Groundwater Level
EXISTING GROUND
LEVEL
Water Table
C’2, ø’2
Clayey Layer
C’3, ø’3
C’1, ø’1
BH
BH
BH Perched WT
Seepage
CROSS SECTION
35
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Stage 2 Stage 2 –– Detailed InvestigationDetailed Investigation• Carry out after optimum building
layout is confirmed.• Refine subsoil profile and obtain soil
parameters.• Soft soil fill area• Major cut and slope• Structures
- Retaining wall- Loading areas
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Selection of Ground Investigation Selection of Ground Investigation MethodsMethods
• Slope and cut area- use Boreholes- SPT and Mazier samples for triaxial tests- Piezometer
• Fill area / soft ground- use Boreholes and Piezocones- Vane shear tests for soft cohesive soil and
Mackintosh probe.- Undisturbed soil sampling for laboratory
strength and consolidation test
36
Staging for Borehole at Mud Flats
37
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
38
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Extent of Ground InvestigationExtent of Ground InvestigationIt depends on:
– Available information.– Geological formation and features.– Variability of subsoil and
groundwater.– Proposed structures and platforms.– Adjacent property.
39
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Preliminary Ground InvestigationPreliminary Ground Investigation• Number/ Spacing (Minimum)• Depth
- Fill area (Compressible with SPT N≈ 30)- Cut Area (Depth of potential slips)
• Structures- up to depth of soil where the pressure
induced by structure has little influence (theoretically)
• Geophysical survey for large area and to determine bedrock profile and characteristics.
Depth of Investigation
Stability Analysis
Foundation Design
40
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Detailed Ground InvestigationDetailed Ground Investigation• Spacing
- Generally 10m to 30m for structures.- Intensified investigation for problem areas.- one at every pier and abutment for bridge.
• Depth of Rock CoringRock Type Minimum core length
Igneous rock 3m - 6m (expected boulders)Sedimentary ( x limestone) 3mLimestone ( x cavity) 10mLimestone with cavity 10m cavities free
41
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Depth of Rock CoringDepth of Rock Coring
• Boulder sizes (Granite formation):– Typically not exceeding 3m but cannot be
ruled out
G&P Geotechnics Sdn Bhd (G&P Geotechnics Sdn Bhd (www.gnpgroup.com.mywww.gnpgroup.com.my))G&P Geotechnics Sdn Bhd
Preboring through boulders
Boulders exposed
after preboring
42
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Depth of Rock CoringDepth of Rock Coring
• In tropical region such as Malaysia with high rainfall, possible cave widths of up to 10m possible (Waltham & Fookes, 2003)
• General guideline on stability of natural rock roof– Stable if the thickness of rock is equal to or
greater than its span
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn BhdCAVERN/CAVITY EXPOSED AFTER EXCAVATION
43
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Laboratory Test
a) Classification- Sieve Analysis- Clay/Silt- Atterberg Limits- Moisture Content- Unit Weight- Specific Gravity
b) Compressibility- Consolidation- Swelling
c) Shear Strength
- Laboratory Vane- UCT- UU- Shear Box
Total
- CIU- CID
Effective
e) Chemical- SO4- CI- Ph- Resistivity- Redox Potential
d) Compaction Fill
44
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
G&P-Form6 (Rev3) G&P GEOTECHNICS SDN. BHD.
(Geotechnical Consultants)
LABORATORY TEST SCHEDULE Project No : ……………………………….. Lab. Schedule No. ……………….. Requested by : …………………………………………… Date : ………………….. Project : ……………………………………………………………………………………..………………… Reviewed by : …………………………………………... Date : ……………………
BOREHOLE SAMPLE NO.
DEPTH m M/C A.L. B.D. S.G.
Direct Shear Box
SIEVE ANALYSIS CONSOLIDATION TRIAXIAL UCT
CHEMICAL ANALYSIS
Mech. Hydro. Std. Rapid S.S. CIU UU OR GANIC CONTENT PH SULPH ATE
CONTENT CHLORIDE CONTENT
TOTAL Requested
Performed
Note : 1) CIU - Isotropic Consolidated Undrained Triaxial Test with pore pressure measurements
- Use 70mm diameter sample (i.e. untrimmed Mazier sample) - Sample should not have side filter during consolidation - Shearing strain should be calculated using Cv values calculated during consolidation stage. - Multi-stage testing not allowed - P-Q Stress Path Plotting shall be submitted.
2) For CIU Tests, stress path and other relevant data shall be submitted in Hard Copy (Plots and Tabulated Data) and Soft Copy (Computer files data). Cell confining pressure of 0.5 σv, 1.0σv, 2.0σv shall be adopted
for the CIU test, where σv is the total vert ical in-situ stress. 3) UU - Unconsolidated Undrained Test (at total overburden pressure of the sample) 4) UCT - Unconfined Compression Test (untrimmed sample)
5) To determine Cv from Consolidation Tests :-
- Use Square-Root Time Method to determine d0.
- Then use Log-Time Method to determine d100
6) Direct shear box test - Three (3) reconstituted specimens (60mm x 60mm x 20mm thick) shall be used. - Applied normal stress pressure of 0.5 σv, 1.0σv, 2.0σv shall be adopted for the shear box test, where σv is the total vertical in-situ stress. 7) All specimens for triaxial or consolidation tests shall be obtained from center of the recovered samples in
UD sampler. 8) 2 moisture content tests shall be carried out on soil immediately besides the specimens retained for triaxial or consolidation tests. 9) Bulk density, particle size distribution and Atterberg Limit tests shall be carried out on every specimen after the triaxial or consolidation tests.
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
Special AttentionSpecial Attention
Triaxial Compression Test
- No/Minimum Trimming
- No Side Drains
- No Multistage
45
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
SITE SUPERVISIONSITE SUPERVISION
• Full time Engineering Geologists, Engineers or experienced Technicians
• Briefing (Supervision Checklist)• Communication• Checklist (http://www.gnpgeo.com.my/RnD_spec_checklist_checklist.asp)
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
CONCLUSIONSCONCLUSIONS1. You pay for soil investigation whether
you carry out or not. In fact you eventually pay more without a soil investigation.
46
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
CONCLUSIONSCONCLUSIONSPrincipal conclusions:1. Delay and escalating
construction costs are due to inadequate site investigation
2. Consequences of inadequate SI is not only severe during design and construction stage but even more serious for full-life costing
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
CONCLUSIONS (CONCLUSIONS (concon’’tt))
2. You must know- why you wanted them- where they are to be carried out- how they should be done
47
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
CONCLUSIONS (CONCLUSIONS (concon’’tt))
3. Use proper specifications
4. Full time supervision
5. Ensure QA/QC system.
48
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
YOU PAY FOR SOIL YOU PAY FOR SOIL INVESTIGATION INVESTIGATION WHETHER YOU WHETHER YOU CARRY OUT OR CARRY OUT OR
NOTNOT
49
Quality Services Quality Services -- Our CommitmentOur Commitment©© G&P Geotechnics Sdn BhdG&P Geotechnics Sdn Bhd
ReferenceReferenceMS 2038: 2006 – Code of Practice for Site Investigations MS 1754: 2004 – Code of Practice for EarthworksMS 1756: 2004 – Code of Practice for FoundationMS 1056: 2005 – Method of Test for Soils for Civil Engineering PurposesClayton, C.R.I. Simons, N.e. & Mathews, M. C. (1982) Site Investigation, A
Handbook for Engineers, Grenada London, 424PEuropean Group Subcommittee (1968)
“Recommended method of Static and Dynamic Penetration Tests 1965”Geotechnique Vol. 1 No. 1
Head, K. H. (1984)Manual of Soil Laboratory testing
GCO (1984) : Geotechnical Manual for Slopes, Geotechnical Control Office, Hong Kong
50
References (contReferences (cont’’d)d)GCO (1980) : Geoguide 2 : Guide to Site Investigation, Geotechnical Control
Office, Hong Kong
Gue, S. S. (1985)
“Geotechnical Assessment for Hillside Development”Proceedings of the Symposium on Hillside Development; Engineering Practice and Local By-Laws, The Institution of Engineers, Malaysia
Neoh, C. A. (1995)
“Guidelines for Planning Scope of Site Investigation for Road Projects”, Public Works Department, Malaysia
Ooi, T.A. and Ting, W.H. (1975)
“The Use of a Light Dynamic Cone Penetrometer in Malaysia”. Proceeding of 4th Southeast Asian Conference on Soil Engineering, Kuala Lumpur, pp. 3-62, 3-79
Ting, W.H. (1972)
“Subsurface Exploration and Foundation Problems in the Kuala Lumpur Area”, Journal of Institution of Engineers, Malaysia, Vol. 13, pp. 19-25
G&P Geotechnics Sdn Bhd
byby Ir. Dr. Gue See Sew & Ir. Chow Chee MengIr. Dr. Gue See Sew & Ir. Chow Chee Meng
INTERPRETATION OF INTERPRETATION OF LABORATORY AND LABORATORY AND
FIELD TEST RESULTS FIELD TEST RESULTS FOR DESIGNFOR DESIGN
http://www.gnpgroup.com.myhttp://www.gnpgroup.com.my
CONTENTSCONTENTS1. INTRODUCTION2. OBJECTIVE3. SCOPE4. INTERPRETATION
5. DESIGN PARAMETER
6. LABORATORY TEST
JKR PROBEJKR PROBESPTSPT
G&P Geotechnics Sdn Bhd
INTRODUCTIONINTRODUCTIONNEED
Neglected topic; only briefly covered in universities
Danger of using results directly without interpretation
Decision on choice of values for soil parameters
SCOPECommon tests only
PROCESSESSpecifications, Supervision, Presentation & Interpretation
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Proton Iswara
G&P Geotechnics Sdn Bhd
Ferrari
OBJECTIVESOBJECTIVES
1) Illustrate the importance of interpretation
2) Show methods of compiling results and recognising errors
G&P Geotechnics Sdn Bhd
SCOPESCOPECommon field and laboratory tests
FIELD TESTSFIELD TESTSJKR/ Mackintosh probe
SPT (Standard Penetration Test)
Piezocone
Field Vane Shear
LABORATORY TESTSLABORATORY TESTSUnconfined compression
Triaxial Test (UU, CIU with pore pressure measurement & CD)
Consolidation
Geonor vane
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
JKR ProbesJKR ProbesPrimitive tool
Limited useShallow bedrock profile (limestone with slump zone)
Weak zone at shallow depth
Shallow foundation• No recent fill and future settlement
• Structure of low risk
• If in doubt – use borehole
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Cased hardened steel pointer of Cased hardened steel pointer of 25mm dia. and 6025mm dia. and 60oo cone.cone.
12mm dia. HY 12mm dia. HY 55C steel rod55C steel rod
Prevent buckling during driving
5kg drop 5kg drop hammerhammer
22mm outer 22mm outer dia. couplingdia. coupling
28
•• ApparatusApparatus
G&P Geotechnics Sdn Bhd
CONE PENETROMETER
G&P Geotechnics Sdn Bhd
For practical application:
- Results of JKR Probe and Mackintosh Probe can be taken as equivalent
- JKR Probe created as equivalent to Mackintosh Probe as Mackintosh Probe is patented in the early days
G&P Geotechnics Sdn Bhd
•• Precautionary measuresPrecautionary measuresFree fall and consistent drop heightFree fall and consistent drop height
Components and apparatus properly Components and apparatus properly washed and oiledwashed and oiled
•• Termination criteriaTermination criteriaBlows/300mmBlows/300mm(maximum 400 blows/300mm)(maximum 400 blows/300mm)
Max 15m depthMax 15m depth
G&P Geotechnics Sdn Bhd
•• Typical test resultsTypical test results
G&P Geotechnics Sdn Bhd
Identifying localised soft/weak or slip plane.Identifying localised soft/weak or slip plane.
•• ApplicationsApplications
G&P Geotechnics Sdn Bhd
Identifying localised soft/weak or slip plane.Identifying localised soft/weak or slip plane.
•• ApplicationsApplications
G&P Geotechnics Sdn Bhd
Identifying nonIdentifying non--compliance fill.compliance fill.
TT
T = compaction lift
G&P Geotechnics Sdn Bhd
Allowable Bearing Capacity V.S. J.K.R. Dynamic Cone Penetration Resistance (After Ooi & Ting, 1975) ** Conditions applied
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
•• Comparison between JKR probe and SPTComparison between JKR probe and SPT
G&P Geotechnics Sdn Bhd
0 100 200 300 400JKR Blows
12
8
4
0
Dep
th (m
)
JKR Plot
0 10 20 30 40 50SPT'N'
12
8
4
0
SPT'N' Plot
G&P Geotechnics Sdn Bhd
0 10 20 30 40SPT'N'
16
12
8
4
0
14
10
6
2
Dep
th (m
)
SPT'N' Plot
0 100 200 300 400JKR Blows
16
12
8
4
0
14
10
6
2
JKR Plot
Number of Blows per 300 mm
Dep
th F
rom
Gro
und
Sur
face
In M
eter
(m)
G&P Geotechnics Sdn Bhd
Shear Strength In kPa
Dep
th F
rom
Gro
und
Sur
face
In M
eter
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Shallow depthShallow depth
Not for gravelly groundNot for gravelly ground
Human errors Human errors (e.g. wrong counting, non(e.g. wrong counting, non--consistent consistent drop height, exerting force to the drop hammerdrop height, exerting force to the drop hammer
Misleading results at greater depthMisleading results at greater depth
•• LimitationsLimitations
A popular testA popular testuseful for pile foundation design
Common errorsCommon errors
G&P Geotechnics Sdn Bhd
Standard Penetration Test (SPT)Standard Penetration Test (SPT)
G&P Geotechnics Sdn Bhd
63.5kg Hammer
760mmFree Fall
450mm
Split-Spoon Sampler
AW Rod
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Driving Shoe
Split Barrel
•• OD = 50mm OD = 50mm •• ID = 35mm ID = 35mm •• Length ~ 650mmLength ~ 650mm
Split-Spoon Sampler
G&P Geotechnics Sdn Bhd
Seating drive
Test drive
SPTSPT--N ValueN Value
G&P Geotechnics Sdn Bhd
SPTSPT--N = x 300 = 143N = x 300 = 143
5 5 -- 10 10 -- 30 30 -- 20/30cm20/30cmSeating drive
Test drive
(30 + 20)(30 + 20)(75 + 30)(75 + 30)
G&P Geotechnics Sdn Bhd
Maximum blows to be applied In seating drive In test drive Soil 25 50 ‘Soft rock’ 25 100
BS1377: Part 9
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Formation Level
G&P Geotechnics Sdn Bhd
CLAY
SAND
SILTY CLAY
G&P Geotechnics Sdn Bhd
Red
uced
Lev
el (f
t)
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
New Technology New Technology ……automaticautomatic
1)1)To obtain soil profile and stiffness To obtain soil profile and stiffness (strength) profile of the subsoil(strength) profile of the subsoil
2)2) To determine coefficient of To determine coefficient of consolidation of soilconsolidation of soil
3)3) Results can also be used directly Results can also be used directly for design (e.g. pile design)for design (e.g. pile design)
G&P Geotechnics Sdn Bhd
Piezocone (CPTu)Piezocone (CPTu)
Piezocone ResultsPiezocone Results
G&P Geotechnics Sdn Bhd
Piezocone ResultsPiezocone Results
G&P Geotechnics Sdn Bhd
Nk = 11-19
Lunne & Kleven (1981)
Nkt = 15
Gue & Tan (2000)
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Cone factors related to plasticity index of the clays (After Dobie & Wong, 1990)
G&P Geotechnics Sdn Bhd
1. Sensitive, fine grained2. Organic soils – peats3. Clays – clay to silty clay4. Silt mixtures – clayey silt to silty clay5. Sand mixtures – silty sand to sandy silt6. Sands – clean sand to silty sand7. Gravelly sand to sand8. Very stiff sand to clayey sand (heavily overconsolidated or cemented)9. Very stiff fine grained (heavily overconsolidated or cemented)
Soil Behaviour Type Classification Charts for CPT(after Robertson, 1990)
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
1)1)Vane test in boreholeVane test in borehole
2)2) Geonor vaneGeonor vane
3)3) Lab vaneLab vaneUseUse-- To determine inTo determine in--situ undrained situ undrained
shear strength (Sshear strength (Suvuv) of soft clayey ) of soft clayey soilssoils
G&P Geotechnics Sdn Bhd
Vane Shear TestVane Shear Test
G&P Geotechnics Sdn Bhd
Most common errorsMost common errors-- Computation Computation –– spring factorspring factor-- Clay with organic materialsClay with organic materialsRecognise errorsRecognise errorsSummarise results with SSummarise results with Suu from from unconfined compression, UU and lab unconfined compression, UU and lab vane superimposedvane superimposedPlot Plot SSuvuv against PIagainst PI
PPoo’’Or SOr Suvuv against Pagainst Poo’’ then find then find
PPoo’’SSuvuv
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Dep
th (f
t)
Shear Strength (lb/ft2)
G&P Geotechnics Sdn Bhd
Foundation DesignFoundation Design• Stability / Bearing Capacity• Settlement Prediction
Bearing CapacityBearing Capacity• Su• C’ and Φ’
Settlement PredictionSettlement Prediction• e vs Log10 p’ (mv, Cc)• cv (k)
G&P Geotechnics Sdn Bhd
Design ParametersDesign Parameters
G&P Geotechnics Sdn Bhd
LABORATORY TESTSLABORATORY TESTS
-- Why?Why?
-- Types of Tests!Types of Tests!
-- How?How?
-- Specifications?Specifications?(Load, Pressure, Time)(Load, Pressure, Time)
G&P Geotechnics Sdn Bhd
SPECIFICATIONSSPECIFICATIONS
A) Consolidation TestA) Consolidation Test1) Which samples are appropriate and suitable for the test?2) For consolidation test
- Load increment
- Pressure
} 0.5Po’ – 8Po’} or to} e 0.42eo~~
B) Triaxial testB) Triaxial test1) For triaxial tests
- Strain rate- Back pressure
Ref: Head, K. H (1984) Ref: Head, K. H (1984) -- Manual of soil Laboratory testingManual of soil Laboratory testingG&P Geotechnics Sdn Bhd
Special AttentionSpecial Attention
Triaxial Compression Test
- No/Minimum Trimming
- No Side Drains
- No Multistage
G&P Geotechnics Sdn Bhd
G&P-Form6 (Rev3) G&P GEOTECHNICS SDN. BHD.
(Geotechnical Consultants)
LABORATORY TEST SCHEDULE Project No : ……………………………….. Lab. Schedule No. ……………….. Requested by : …………………………………………… Date : ………………….. Project : ……………………………………………………………………………………..………………… Reviewed by : …………………………………………... Date : ……………………
BOREHOLE SAMPLE NO.
DEPTH m M/C A.L. B.D. S.G.
Direct Shear Box
SIEVE ANALYSIS CONSOLIDATION TRIAXIAL UCT
CHEMICAL ANALYSIS
Mech. Hydro. Std. Rapid S.S. CIU UU OR GANIC CONTENT PH SULPH ATE
CONTENT CHLORIDE CONTENT
TOTAL Requested
Performed
Note : 1) CIU - Isotropic Consolidated Undrained Triaxial Test with pore pressure measurements
- Use 70mm diameter sample (i.e. untrimmed Mazier sample) - Sample should not have side filter during consolidation - Shearing strain should be calculated using Cv values calculated during consolidation stage. - Multi-stage testing not allowed - P-Q Stress Path Plotting shall be submitted.
2) For CIU Tests, stress path and other relevant data shall be submitted in Hard Copy (Plots and Tabulated Data) and Soft Copy (Computer files data). Cell confining pressure of 0.5 σv, 1.0σv, 2.0σv shall be adopted
for the CIU test, where σv is the total vert ical in-situ stress. 3) UU - Unconsolidated Undrained Test (at total overburden pressure of the sample) 4) UCT - Unconfined Compression Test (untrimmed sample)
5) To determine Cv from Consolidation Tests :-
- Use Square-Root Time Method to determine d0.
- Then use Log-Time Method to determine d100
6) Direct shear box test - Three (3) reconstituted specimens (60mm x 60mm x 20mm thick) shall be used. - Applied normal stress pressure of 0.5 σv, 1.0σv, 2.0σv shall be adopted for the shear box test, where σv is the total vertical in-situ stress. 7) All specimens for triaxial or consolidation tests shall be obtained from center of the recovered samples in
UD sampler. 8) 2 moisture content tests shall be carried out on soil immediately besides the specimens retained for triaxial or consolidation tests. 9) Bulk density, particle size distribution and Atterberg Limit tests shall be carried out on every specimen after the triaxial or consolidation tests.
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Consolidation SettlementConsolidation Settlement
CONSOLIDATION TEST RESULTS
Void Ratio
Cv m²/year
Coefficient of Volume Change
Mv X 10ˉ³ m² / KN
G&P Geotechnics Sdn Bhd
Dep
th (m
)
G&P Geotechnics Sdn Bhd
Compression Index
Coefficient of Consolidation, Ch m²/yr
Dep
th (m
)
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
NAVFAC DM7.1
Log time methodRoot time method
G&P Geotechnics Sdn Bhd
Compression index, CCompression index, Ccc and and Recompression index, CRecompression index, Crr
a) a) CCcc = 0.009 (LL = 0.009 (LL –– 10%)10%) For inorganic soils,For inorganic soils,with sensitivity less with sensitivity less than 4than 4
b) b) CCcc = 0.007 (LL = 0.007 (LL –– 10%)10%) For normally For normally consolidated clayconsolidated clay
c) c) CCcc = 0.0115 W= 0.0115 Wnn For organic soils, peatFor organic soils, peat
d) d) CCcc = 1.15 (e= 1.15 (eoo –– 0.35)0.35) For all claysFor all clays
e) e) CCcc = (1 + e= (1 + eoo) [0.1 + (W) [0.1 + (Wnn –– 25)0.006]25)0.006] For varved claysFor varved clays
f) f) CCcc = 0.5*PI*G= 0.5*PI*Gss For OC claysFor OC clays
Compression index, CCompression index, Ccc and and Recompression index, CRecompression index, Crr
•• For inorganic normally For inorganic normally --consolidated Klang Clay (Tan et consolidated Klang Clay (Tan et al., 2004):al., 2004):–– CCcc = 0.02LL = 0.02LL –– 0.870.87–– CCcc = 0.61e= 0.61eoo –– 0.170.17–– CCcc = 0.02 W= 0.02 Wnn –– 0.370.37
•• CCrr ≈≈ (0.1 to 0.2)*C(0.1 to 0.2)*Ccc
Coefficient of secondary compression, CCoefficient of secondary compression, Cαα
•• CCαα / C/ Ccc = 0.04 = 0.04 ±± 0.010.01 For inorganic soft claysFor inorganic soft clays
•• CCαα / C/ Ccc = 0.02 = 0.02 ±± 0.010.01 For granular soils including For granular soils including rockfillrockfill
•• CCαα / C/ Ccc = 0.03 = 0.03 ±± 0.010.01 For shale and mudstoneFor shale and mudstone
•• CCαα / C/ Ccc = 0.05 = 0.05 ±± 0.010.01 For organic clays and siltsFor organic clays and silts
•• CCαα / C/ Ccc = 0.06 = 0.06 ±± 0.010.01 For peat and muskegFor peat and muskeg
TWO Major Categories :
(1)(1) Strength Parameters :Strength Parameters :
-- Stability Analyses of Slopes & Embankment.Stability Analyses of Slopes & Embankment.
-- Bearing Capacity Analyses for Foundation.Bearing Capacity Analyses for Foundation.
(2)(2) Stiffness & Deformation Parameters :Stiffness & Deformation Parameters :Prediction & evaluation of :Prediction & evaluation of :--Settlement, Heave, Lateral deformation, Settlement, Heave, Lateral deformation, Volume Change.Volume Change.
Interpretation of Laboratory TestsInterpretation of Laboratory Tests
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Conventional Foundation for Low Rise Buildings
G&P Geotechnics Sdn Bhd
Conventional Foundation for Low Rise Buildings (Soil Settlement)
G&P Geotechnics Sdn Bhd
Exposed Pile
Settlement
Settling Platform Detached from Building
G&P Geotechnics Sdn Bhd
TWO Conditions :
(A)(A) Total Stress :Total Stress :
-- For Short Term Conditions in Cohesive Soils.For Short Term Conditions in Cohesive Soils.
-- Little of no drainage. Little of no drainage.
(B)(B) Effective Stress :Effective Stress :-- For Long Term & Permanent Conditions.For Long Term & Permanent Conditions.
-- Fully Fully ““DrainedDrained”” Conditions.Conditions.
Strength ParametersStrength Parameters
G&P Geotechnics Sdn Bhd
Simple CheckSimple Check
qqallowallow = (N= (Ncc..ssuu / FOS)/ FOS)qqallowallow == allowable bearing pressure allowable bearing pressure
= = ((γγfillfill.H + 10) .H + 10) (( in kPain kPa))
NNcc == 55
HHfailurefailure = (5 x Su) / = (5 x Su) / γγfillfille.g. :e.g. :When When Su = 10 kPa ; Su = 10 kPa ; γγfill fill = 18 kN/m= 18 kN/m33
HHfailurefailure = (5 x 10)/ 18 = 2.8 m= (5 x 10)/ 18 = 2.8 mG&P Geotechnics Sdn Bhd
Clough et al. (1989)
Excavation: Check Depth of ExcavationExcavation: Check Depth of Excavation
G&P Geotechnics Sdn Bhd
Undrained Shear Strength, su from :
(i)(i) Unconfined Compression Test, UCTUCT
(ii)(ii) Unconsolidated Undrained Triaxial Test, UUUU
(iii)(iii) Laboratory Vane Shear TestLaboratory Vane Shear Test
Total Stress Strength, Total Stress Strength, ssuu
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
Typical Set-up of Triaxial Test
a)Base
b)Removable cylinder and top cap
c)Loading ram
d)Rubber membrane
Equipment for Triaxial TestEquipment for Triaxial Test
Effective Stress StrengthEffective Stress StrengthParameters c’ & φ’ Interpretation from
(i)(i) Isotropic Consolidated Undrained Triaxial Test, CIU + CIU + ΔΔUU
(ii)(ii) Isotropic Consolidated Drained Triaxial Test, CIDCID
(iii)(iii) Laboratory Shear Box Test Laboratory Shear Box Test (at v. slow (at v. slow rate)rate)
Note : Advantage to use Stress PathNote : Advantage to use Stress PathG&P Geotechnics Sdn Bhd
Mohr-Coulomb
G&P Geotechnics Sdn Bhd
Stress Path InterpretationStress Path InterpretationTwo types of Plot
(i)(i) MIT MIT Stress Path Plot Stress Path Plot (T.W. Lambe of MIT, 1967)
(ii)(ii) Cambridge Cambridge Stress Path Plot Stress Path Plot
The vertical axis : t = (σ1 - σ3)/2 = (σ’1 - σ’3)/2The horizontal axis :s = (σ1 + σ3)/2 & s’ = (σ’1 + σ’3)/2
(Roscoe, Schofield and Wroth (1958) at the Cambridge, England)The vertical axis :
q = σ1 - σ3 = σ’1 - σ’3The horizontal axis :p = (σ1 + σ2 + σ3)/3 & p’ = (σ’1+ σ’2+σ’3)/3
G&P Geotechnics Sdn BhdTerminology & Interpretation
MIT & Cambridge Stress Path PlotMIT & Cambridge Stress Path Plot
MIT & Cambridge Stress Path PlotMIT & Cambridge Stress Path Plot
Tan θ = t’ / sTan θ = Sin φ’K = c’ Cos φ’
C’ = KCos φ’
Tan η = q / p’Sin φ’ = (3 η) / ( 6 + η )r = c’ (6 Cos φ’) / (3 – Sin φ’)
C’ =r (3 – Sin φ‘)
6 Cos φ’
G&P Geotechnics Sdn Bhd
For Slopes & Walls AnalysesFor Slopes & Walls AnalysesParameter cParameter c’’ and and φφ’’ shall be shall be Interpreted fromInterpreted from
i)i) Isotropically Consolidated Undrained Isotropically Consolidated Undrained Triaxial Test, CIU + Triaxial Test, CIU + ΔΔuu
ii)ii)Isotropically Consolidated Drained Isotropically Consolidated Drained Triaxial Test, CIDTriaxial Test, CID
iii)iii)Laboratory Shear Box Test (at very Laboratory Shear Box Test (at very slow rate)slow rate)
Note: Advantage to use Stress PathNote: Advantage to use Stress Path
G&P Geotechnics Sdn Bhd
Large Strain
G&P Geotechnics Sdn Bhd
Scattered CIU Results
0 50 100 150 200 250 300 350 400 450 500s' = (σ1'+σ3')/2
0
50
100
150
200
250
300
350
400
450
500
t' =
(σ1'
- σ3')
/2
BH1 UD2BH2 UD1BH2 M1BH3 UD2BH4 UD1BH5 M1BH6 M1BH6 M2BH9 M1BH10 UD1BH10 UD3
0 50 100 150 200 250 300 350 400 450 500
0
50
100
150
200
250
300
350
400
450
500
Upper Boundc’ = 5 kPa, φ’ = 39º
Lower Boundc’ = 0 kPa, φ’ = 29º
Proposed Design Linec’ = 3.5 kPa, φ’ = 32º
φ’ = sin-1 mc’ = a / (cos φ’)
a
1m
G&P Geotechnics Sdn Bhd
Correlations for Preliminary Assessment of φ’
G&P Geotechnics Sdn Bhd
φφ’’ Values vs Plasticity IndexValues vs Plasticity Index (after Terzaghi)(after Terzaghi)
Typical PI = 30% to 70%(Malaysia Soft Clay)G&P Geotechnics Sdn Bhd
ΦΦ’’ Values vs Clay ContentValues vs Clay Content (Skempton, 1964)(Skempton, 1964)
G&P Geotechnics Sdn Bhd
ΦΦ’’ vs % of Finesvs % of Fines
Figure 3 : φ’peak versus Percentage of Fines in Residual Soils
30
35
25
G&P Geotechnics Sdn Bhd
cc’’ vs % of Finesvs % of Fines
Figure 4 : c’ versus Percentage of Fines in Residual SoilsG&P Geotechnics Sdn Bhd
Correct InterpretationCorrect Interpretation
Undrained Shear StrengthUndrained Shear Strength
•• Limitations of UU Tests:Limitations of UU Tests:–– Sample disturbanceSample disturbance–– Negative pore pressures generated during Negative pore pressures generated during
removal of sample from tuberemoval of sample from tube
•• Undrained shear strength is best Undrained shear strength is best obtained from inobtained from in--situ testing such as situ testing such as field vane, piezocone, etc.field vane, piezocone, etc.
YOU PAY FOR YOU PAY FOR SOIL SOIL INVESTIGATIONINVESTIGATIONWHETHER YOU WHETHER YOU CARRY OUT OR CARRY OUT OR
NOTNOT
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
REFERENCESREFERENCESASTM, (1986)
Standard Test Method for Deep Quasi-static, Cone and Friction Cone Penetration Tests of Soil, D3441-86, ASTM Committee D-18 on Soil and Rock, USA
Dobie, M.J.D., & Wong, J.T.F. (1990)“Piezocone testing; Interpretation in Malaysia Alluvial Clays” Geotechnical Aspects of the North-South Expressway, PLUS & PL, Kuala Lumpur
Fleming, W.G.K. et al (1985)Piling Engineering Survey University Press, Glasgow
International Society for Soil Mechanics and Foundation (1988)International Reference Test Procedure, ISSMFE Technical Committee on Penetration Testing, Proposal to ISSMFE, Orlando, USA
Head, K. H (1984)Manual of Soil Laboratory Testing
G&P Geotechnics Sdn Bhd
REFERENCESREFERENCES
Proceedings of 1st InternationalSymposium on Penetration Testing/ ISOPT – I/Florida, USA, 1988
Proceedings of 2nd EuropeanSymposium on Penetration Testing/ ESOPT – II/ Amsterdam/ May 1982
Robertson, P.K. and Campanella, R.G. (1988)Guidelines for using the CPT, CPTU and Marchetti DMT for Geotechnical Design, U.S. Department of Transportation, Federal Highway Administration, Office of Research and Special Studies, Report No. FHWA-PA-87-023+84-24
Meigh, A.C. (1987)Cone Penetration Testing: Methods and Interpretation, Construction Industry Research and Information Association, CIRIA Ground Engineering Report: In-site Testing, London
G&P Geotechnics Sdn Bhd
Sanglerat, G, (1972)The Penetrometer and Soil Exploration, Elsevier Publishing Company, Amsterdam, Netherlands
Teh, C.I. and Houlsby, G.T. (1991)An Analytical Study of the Cone Penetration Test in Clay, Geotechnique, Vol. 41, No. 1, pp: 17-34
REFERENCESREFERENCES
Gue, S.S. & Tan, Y.C. (2003)Current Status & Future Development of Geotechnical Engineering Practice in Malaysia, 12th ARC on Soil Mechanics & Geotechnical Engineering, Singapore
Gue, S.S. & Tan, Y.C. (2006)
Landslides: Abuses of the Prescriptive Method, International Conference on Slopes, Malaysia
G&P Geotechnics Sdn Bhd
PILED FOUNDATION PILED FOUNDATION DESIGN & CONSTRUCTIONDESIGN & CONSTRUCTION
By Ir. Dr. Gue See Sew & Ir. Chow Chee Menghttp://www.gnpgeo.com.my
ContentsContents
Overview
Preliminary Study
Site Visit & SI Planning
Pile Design
Pile Installation Methods
Types of Piles
Contents (ContContents (Cont’’d)d)Piling Supervision
Pile Damage
Piling Problems
Typical Design and Construction Issues
Myths in Piling
Case Histories
Conclusions
Overview
What is a Pile Foundation
It is a foundation system that transfers loads to a deeper and competent soil layer.
When To Use Pile Foundations
• Inadequate Bearing Capacity of Shallow
Foundations
• To Prevent Uplift Forces
• To Reduce Excessive Settlement
PILE CLASSIFICATIONPILE CLASSIFICATION
Friction Pile– Load Bearing Resistance derived mainly
from skin friction
End Bearing Pile– Load Bearing Resistance derived mainly
from base
Friction Pile
Overburden Soil Layer
End Bearing Pile
Rock / Hard Layer
Overburden Soil
Preliminary Study
Preliminary StudyPreliminary Study
Type & Requirements of Superstructure
Proposed Platform Level (ie CUT or FILL)
Geology of Area
Previous Data or Case Histories
Subsurface Investigation Planning
Selection of Types & Size of Piles
Previous Data & Case Previous Data & Case HistoriesHistories
Bedrock Profile
Existing Development
A
Existing Development
BProposed
Development
Only Need Minimal Number of Boreholes
Challenge The Norm Thru Innovation To Excel
SELECTION OF PILESSELECTION OF PILES
Factors Influencing Pile Selection– Types of Piles Available in Market (see Fig. 1)– Installation Method– Contractual Requirements– Ground Conditions (eg Limestone, etc)
– Site Conditions & Constraints (eg Accessibility)
– Type and Magnitude of Loading– Development Program & Cost– etc
TYPE OF PILES
DISPLACEMENT PILES NON-DISPLACEMENT PILES
TOTALLY PREFORMED PILES(A ready-made pile is driven or jacked
into the ground)
DRIVEN CAST IN-PLACE PILES(a tube is driven into ground to
form void)
Bored piles Micro piles
HollowSmall displacement
Solid
Steel Pipe Concrete Spun Piles
Concrete Tube
Closed ended tube concreted with tube left in position
Closed ended tube
Steel Tube
Open ended tube extracted while concreting (Franki)
Concrete Steel H-piles(small displacement)
Bakau pilesTreated timber pile
Precast R.C. piles
Precast prestressedpiles
FIG 1: CLASSIFICATION OF PILES
Restricted use due to environmental considerations
Caisson piles
BA
KA
U P
ILE
S
TIM
PE
R P
ILE
S
RC
PIL
ES
PS
C P
ILE
S
SP
UN
PIL
ES
STE
EL
H P
ILE
S
STE
EL
PIP
E P
ILE
S
JAC
KE
D P
ILE
S
<100 KN a a a ? ? ? ? a x ? a
100-300 a a a ? ? a a a x a a
300-600 ? a a a a a a a a a a
600-1100 x ? a a a a a ? a a ?
1100-2000 x ? a a a a a ? a a ?
2000-5000 x x a a a a a ? a a ?
5000-10000 x x a a a a a x a a x
>10000 x x ? a a a a x a ? x
<5m ? ? ? ? ? ? ? x a a ?
5-10m a a a a a a a ? a a a
10-20m ? ? a a a a a a a a a
20-30m x x a a a a a a a a a
30-60m x x a a a a a a a ? a
a a a a a ? a a a ? a
a a a a a a a a a ? a
? ? ? ? ? a a a ? a a
x x a a a a a ? a a ?x x ? ? ? a a ? a a ?x ? a a a a a a a a a
a a a a a a a a a ? a
a a a a a a a a a a a
? a a a a a a a a a a
x ? a a a a a a a a a
a a a a a a a a a a a
? a a a a a a a a a a
x ? a a a a a a a a a
V. DENSE SPT > 50 x x a a a a a ? a a ?
S < 100 mm x ? a a a a a a a a ?
100-1000mm x x ? ? ? a a ? a a x
1000-3000mm x x ? ? ? ? ? ? ? a x
>3000mm x x ? ? ? ? ? ? ? a x
a a a a a a a a a a a
x a a a a a a a a a a
a a ? ? ? ? ? a a a a
? ? ? ? ? ? ? a ? a a
1-2 0.5-2 1.5-3 1-2.5
AU
GE
RE
D P
ILE
S
COMPRESSIVE LOAD PER COLUMN
SC
ALE
OF
LOA
D
(STR
UC
TUR
AL)
1.0-3.5
PREVENTION OF EFFECTS ON ADJOINING STRUCTURES
(SUPPLY & INSTALL) RM/TON/M 0.5-2.5 0.3-2.0
LOOSE SPT < 10
UNIT COST
GROUND WATER
TYP
E O
F IN
TER
ME
DIA
TE L
AY
ER
GE
OTE
CH
NIC
AL TY
PE
OF
BE
AR
ING
LA
YE
RB
EA
RIN
G T
YP
E
ENVIRONMENT
MIC
RO
PIL
ES
BO
RE
D P
ILE
S
PREFORMED PILES
M. DENSE SPT = 10 - 30
MAINLY END -BEARING (D=Anticipated depth of bearing)
PARTLY FRICTION + PARTLY END BEARING
MAINLY FRICTION
LIMESTON FORMATION
M. STIFF SPT = 4 - 15
V. STIFF SPT = 15 - 32
HARD SPT > 32
DENSE / VERY DENSE SAND
SOFT SPT < 4
WEATHERED ROCK / SOFT ROCK
NOISE + VIBRATION; COUNTER MEASURES REQUIRED
BELOW PILE CAP
ROCK (RQD > 70%)
DENSE SPT = 30 - 50
COHESIVE SOIL
COHESIVELESS SOIL
SOIL WITH SOME BOULDERS / COBBLES (S=SIZE)
ABOVE PILE CAP
DESIGN CONSIDERATIONS
TYPE OF PILE
LEGEND :
8
x
?
INDICATES THAT THE PILE TYPE IS SUITABLEINDICATES THAT THE PILE TYPE IS NOT SUITABLE
INDICATES THAT THE USE OF PILE TYPE IS DOUBTFUL OR NOT COST EFFECTIVE UNLESS ADDITIONAL
MEASURES TAKEN
FIG 2 : PILE SELECTION CHART
Pile Selection Based on CostDetails: 250mm Spun Piles 300mm Spun Piles Micropile
Total Points 83 70 70
Average Length 9m 9m 9m
Average Rock Socket Length - - 2.5m
Indicative Rates :
Mob & Demob RM 50,000.00 RM 50,000.00 RM 20,000.00
Supply RM 33.00 / m RM 42.00 / m -
Drive RM 30.00 / m RM 32.00 / m -
Cut Excess, Dispose + Starter Bars RM 200.00 / Nos RM 200.00 / Nos -
Movement - - RM 200.00 / Nos
Drilling in Soil - - RM 110.00 / m
Drilling in Rock - - RM 240.00 / m
API Pipe - - RM 120.00 / m
Grouting - - RM 85.00 / m
Pile Head - - RM 150.00 / Nos
Est. Ave. Cost Per Point RM 967.00 / Nos RM 1,066.00 / Nos RM 4,297.50 / Nos
Est. Foundation Cost RM 190,261.00 RM 184,620.00 RM 380,825.00
√
Site Visit and SI Planning
Site VisitSite VisitThings To Look For …
Accessibility & Constraints of Site
Adjacent Structures/Slopes, Rivers, Boulders, etc
Adjacent Activities (eg excavation)
Confirm Topography & Site Conditions
Any Other Observations that may affect Design and Construction of Foundation
Subsurface Investigation (SI) Subsurface Investigation (SI) PlanningPlanning
Provide Sufficient Boreholes to get Subsoil Profile
Collect Rock Samples for Strength Tests (eg UCT)
In-Situ Tests to get consistency of ground (eg SPT)
Classification Tests to Determine Soil Type Profile
Soil Strength Tests (eg CIU)
Chemical Tests (eg Chlorine, Sulphate, etc)
Typical CrossTypical Cross--Section at Hill Site Section at Hill Site
Ground Level
Bedrock LevelVery Hard Material Level
Hard Material Level
Groundwater Level
EXISTING GROUND
LEVEL
Water Table
C’2, ø’2
Clayey Layer
C’3, ø’3
C’1, ø’1
BH
BH
BH Perched WT
Seepage
CROSS SECTION
Placing Boreholes in Limestone Areas
Stage 1 : Preliminary S.I.- Carry out geophysical survey (for large areas)
Stage 2: Detailed S.I. - Boreholes at Critical Areas Interpreted from Stage 1
Stage 3: During Construction- Rock Probing at Selected Columns to supplement Stage 2
Pile Design
PILE DESIGNPILE DESIGN
Allowable Pile Capacity is the minimum of :
1) Allowable Structural Capacity
2) Allowable Geotechnical Capacitya. Negative Skin Frictionb. Settlement Control
PILE DESIGNPILE DESIGNStructural consideration
• Not overstressed during handling, installation & in service for pile body, pile head, joint & shoe.
• Dimension & alignment tolerances (common defects?)
• Compute the allowable load in soft soil (<10kPa) over hard stratum (buckling load)
• Durability assessment
Pile Capacity Design Pile Capacity Design Structural CapacityStructural Capacity
Concrete Pile
Steel Pile
Prestressed Concrete Pile
QQallall = 0.25 x = 0.25 x ffcucu x Ax Acc
QQallall = 0.3 x = 0.3 x ffyy x Ax Ass
QQallall = 0.25 (= 0.25 (ffcucu –– PrestressPrestress after loss) x Aafter loss) x Acc
Qall = Allowable pile
capacity
fcu = characteristic strength
of concrete
fs = yield strength of steel
Ac = cross sectional area of
concrete
As = cross sectional area of
steel
SPT Blow Count per 300mm Penetration
Collection of SI DataCollection of SI Data
Pile Capacity Design Pile Capacity Design Geotechnical CapacityGeotechnical Capacity
4000 50 100 150 200 250 300 35026
24
22
20
18
16
14
12
10
8
6
4
2
0
12
10
8
6
4
2
00 50 100 150 200 250 300 350 400
Dep
th (m
)
Upper Bound
Lower Bound
Design Line (Moderately
Conservative)
Depth Vs SPT-N Blow Count
0 50 100 150 200 250 300 350 400
26
24
22
20
18
16
14
12
10
8
6
4
2
0
12
10
8
6
4
2
0
0 50 100 150 200 250 300 350 400
0 50 100 150 200 250 300 350 400
26
24
22
20
18
16
14
12
10
8
6
4
2
0
12
10
8
6
4
2
0
0 50 100 150 200 250 300 350 400
Upper Bound
Lower Bound
Design Line Upper Bound
Lower Bound Design Line
Dep
th (m
)
Depth Vs SPT-N Blow Count
SPT Blow Count per 300mm Penetration
Dep
th (m
)
Depth Vs SPT-N Blow Count
SPT Blow Count per 300mm Penetration
Collection of SI DataCollection of SI Data
Pile Capacity Design Pile Capacity Design Geotechnical CapacityGeotechnical Capacity
Moderately Conservative Moderately Conservative Design ParametersDesign Parameters
Eurocode 7 definition:– Characteristic value of a geotechnical
parameter shall be selected as a cautious estimate of the value affecting the occurrence of the limit state
– In other words, moderately conservative
Moderately Conservative Moderately Conservative Design ParametersDesign Parameters
If at least 10 test results are available:
– A value of 0.5D below the mean of the test results provides a useful indication of the characteristic value
1. Contribution to Discussion Session 2.3, XIV ICSMFE, Hamburg, Balkema, Schneider H R (1997) – Definition and determination of characteristic soil properties. Discussion to ISSMFE Conference, Hamburg.
2. Extracted from Prof. Brian Simpson’s Course Note (2-day Course on Eurocode 7 Geotechnical Design to EC7, 13-14 November 2007, PJ, Malaysia).
Extracted from Prof. Brian Simpson’s Course Note (2-day Course on Eurocode 7 Geotechnical Design to EC7, 13-14 November 2007, PJ, Malaysia).
•• Piles installed in a group may fail:Piles installed in a group may fail:• Individually
• As a block
Pile Capacity Design Pile Capacity Design Geotechnical CapacityGeotechnical Capacity
• Piles fail individually• When installed at large spacing
Pile Capacity Design Pile Capacity Design Geotechnical CapacityGeotechnical Capacity
• Piles fail as a block• When installed at close spacing
Pile Capacity Design Pile Capacity Design Geotechnical CapacityGeotechnical Capacity
Pile Capacity Design Pile Capacity Design Single Pile CapacitySingle Pile Capacity
Pile Capacity DesignPile Capacity DesignFactor of Safety (FOS)Factor of Safety (FOS)
Factor of Safety (FOS) is required for
Natural variations in soil strength & variations in soil strength & compressibilitycompressibility
Pile Capacity DesignPile Capacity DesignFactor of Safety (FOS)Factor of Safety (FOS)
Factor of Safety is (FOS) required for
Different degree of Different degree of mobilisationmobilisation for shaft for shaft & for tip& for tip Lo
adSettlement≈ 5mm
qsmob
qbmob
Load
Settlement≈ 5mm
qsmob
qbmob
Pile Capacity Design Pile Capacity Design Factor of Safety (FOS)Factor of Safety (FOS)
PartialPartial factors of safety for shaft & base factors of safety for shaft & base capacities respectivelycapacities respectively
For shaft, use 1.5 (typical)For shaft, use 1.5 (typical)
For base, use 3.0 (typical)For base, use 3.0 (typical)ΣQsu + Qbu
1.5 3.0Qall =
Pile Capacity DesignPile Capacity DesignFactor of Safety (FOS)Factor of Safety (FOS)
GlobalGlobal factor of safety for total ultimate factor of safety for total ultimate capacitycapacity
Use 2.0 (typical)Use 2.0 (typical)
ΣQsu + Qbu
2.0Qall =
Pile Capacity Design Pile Capacity Design Factor of Safety (FOS)Factor of Safety (FOS)
Calculate using Calculate using BOTHBOTH approaches approaches (Partial & Global)(Partial & Global)
Choose the Choose the lower lower of the of the QQallall valuesvalues
QQuu = Q= Qss + + QQbb
Overburden Soil Layer
Qs = skin friction
Qb = end bearing
Qu = ultimate bearing capacity
Pile Capacity Design Pile Capacity Design Single Pile CapacitySingle Pile Capacity
Qu = α.sus.As + sub.Nc.Ab
Qsu Qbu
Qu = Ultimate bearing capacity of the pile a = adhesion factor (see next slide)sus = average undrained shear strength for shaftAs = surface area of shaft sub = undrained shear strength at pile baseNc = bearing capacity factor (taken as 9.0) Ab = cross sectional area of pile base
Pile Capacity Design Pile Capacity Design Single Pile Capacity : In Cohesive SoilSingle Pile Capacity : In Cohesive Soil
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: In Cohesive SoilIn Cohesive SoilAdhesion factor (Adhesion factor (αα) ) –– Shear strength (SShear strength (Suu) )
(McClelland, 1974)(McClelland, 1974)
Adhesion Factor
Su (kN/m2)25 75 100 125 150 17550
0
0.6
0.2
0.4
0.8
1.0
Cα/Su
Preferred Design Line
Meyerhof Fukuoka
SPT N fsu=2.5N(kPa)
su = (0.1+0.15N)*50
(kPa)α
fsu=α.su(kPa)
0 0 5 1 5
1 2.5 12.5 1 12.5
5 12.5 42.5 0.7 29.75
10 25 80 0.52 41.6
15 37.5 117.5 0.4 47
20 50 155 0.33 51.15
30 75 230 0.3 69
40 100 305 0.3 91.5
Correlation Between SPT N and Correlation Between SPT N and ffsusufsu vs SPT N
0
10
20
30
40
50
60
70
80
90
100
110
0 5 10 15 20 25 30 35 40 45
SPT N
fsu
(kP
a)
Meyerhof Fukuoka
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: In Cohesive SoilIn Cohesive Soil
Values of undrained shear strength, su can be obtained from the following:
Unconfined compressive test
Field vane shear test
Deduce based on Fukuoka’s Plot (minimum su )
Deduce from SPT-N values based on Meyerhof
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: In Cohesive SoilIn Cohesive Soil
NOTE: Use only direct field data for shaft friction prediction instead of Meyerhof
Modified Meyerhof (1976):
Ult. Shaft friction = Qsu ≅ 2.5N (kPa)
Ult. Toe capacity = Qbu ≅ 250N (kPa)
or 9 su (kPa)
(Beware of base cleaning for bored piles –
ignore base capacity if doubtful)
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: In Cohesive SoilIn Cohesive Soil
Modified Meyerhof (1976):Modified Meyerhof (1976):
Ult. Shaft Friction = Ult. Shaft Friction = QQsusu ≅≅ 2.0N (2.0N (kPakPa))
Ult. Toe Capacity= Ult. Toe Capacity= QQbubu ≅≅ 250N 250N –– 400N 400N
((kPakPa))
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: In In CohesionlessCohesionless SoilSoil
Note: Correlations for driven piles. Research by G&P indicates the correlations may be too conservative for jack-in piles
0 200 400 600
20
16
12
8
4
0
Dep
th (m
)
0 100 200 300 400 500Load (kN)
20
16
12
8
4
0
Pile Capacity DesignPile Capacity Design
ΣQsu
Qbu
ΣQsu + Qbu
0 200 400 600
20
16
12
8
4
0
Dep
th (m
)
0 100 200 300 400 500Load (kN)
20
16
12
8
4
0
0 200 400 600
20
16
12
8
4
0
Dep
th (m
)
0 100 200 300 400 500Load (kN)
20
16
12
8
4
0
0 200 400 600
20
16
12
8
4
0
Dep
th (m
)
0 100 200 300 400 500Load (kN)
20
16
12
8
4
0
ΣQsu + Qbu2.0
0 200 400 600
20
16
12
8
4
0
Dep
th (m
)
0 100 200 300 400 500Load (kN)
20
16
12
8
4
0
ΣQsu + Qbu1.5 3.0
SemiSemi--empirical Method (SPTempirical Method (SPT--N)N)Shaft : Shaft : ffsusu = = KKsusu ×× SPTSPT--NNTip Tip : : ffbubu = = KKbubu ×× SPTSPT--NN
From Malaysian experience:From Malaysian experience:
KKsusu = 2.0= 2.0KKbubu = 7.0 to 60 (depending on workmanship)= 7.0 to 60 (depending on workmanship)
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: For Bored PilesFor Bored Piles
Base cleaning of bored piles– Difficult and no practical means of verification
during construction avaliable
Base resistance require large movement to mobilise
Base contribution in bored pile design ignored unless proper base cleaning can be assured and verified (or base grouting, etc.)
Pile Capacity DesignPile Capacity DesignSingle Pile Capacity:Single Pile Capacity: For Bored PilesFor Bored Piles
ROCK SOCKET DESIGNROCK SOCKET DESIGN
Allowable Bearing Pressure on Rockqa = Ksp qu
qa = average bearing pressurequ = average unconfined compressive
strength of rockKsp = an empirical coefficient, which includes
a factor of 3 and ranges from 0.1 to 0.4
Ref: Canadian Foundation Engineering Manual
SPACING OF DISCONTINUITIES
SPACING WIDTH (m)*
APPROXIMATE RQD VALUE
Ksp
Moderately closeWideVery wide
0.3-11-3>3
≥ 25%≥ 75%≥ 90%
0.10.250.4
Bearing Capaciy of Rock Socket
1. Allowable Bearing Resistance on Rock Socket Base
qa = qu Kspdqu = average unconfined compressive strength of
rock coreKsp = empirical factor, and including a factor of 3
d = depth factor = 1 + 0.4 (Ls / Bs)≤ 3
where Ls = depth (length) of the socketBs = diameter of the socket
2. Allowable Shaft Resistanceqa = b β
Pa FOS
qu = Unconfined compressive strength of rock coreFOS = Factor of safety, generally 2Pa = Atmospharic pressure
b = an empirical factor (= 0.63 – lower bound, 1.42 – upper bound)β = rock mass fracturing factor
Combination of base and shaft resistance could only be considered when the base of pile could be cleaned with certainty
< < 0.05 fc
where fc = characteristics strength of concrete
paqu /
Allowable Shaft ResistanceAllowable Shaft ResistanceAPPROXIMATE RQD
VALUEβ
≥ 25%≥ 75%≥ 90%
0.40.60.9
Allowable Shaft ResistanceAllowable Shaft Resistance(EXAMPLE)(EXAMPLE)
Upper bound (b = 1.4)
Lower bound (b = 0.63)β = 0.6
Range of acceptable values – higher shaft resistance can be adopted if
verified by instrumented static load test results
Verification of Rock SocketVerification of Rock Socket
Recommended definition of rock coring shall fulfill all three (3) criteria below:
– Change of tools to rock coring tools, and
Verification of Rock SocketVerification of Rock Socket
– The rock materials shall be verified by carrying out point load test on at least three (3) rock samples to achieve minimum index strength, Is(50) of 3 MPasubject to site confirmation on typical rock lump sizes based on the size correction factor, F = (De/50)0.45 where De is the equivalent core diameter in mm (Is(50) = F*Is), and
Verification of Rock SocketVerification of Rock Socket
– The value of Is(50) varies for different rock formation and site conditions. Therefore, the Geotechnical Engineer designing the bored piles have to determine the proper value to be used as it is also related to rock socket capacity adopted for the bored piles.
Typical example of relationship
between UCT and Is(50)
- Specific for each site
Verification of Rock SocketVerification of Rock Socket
- Recovered rock coring materials of more than 50% subject to site calibration upon start work unless otherwise agreed by the engineer.
Point Load Test
(UCS of Intact Rock)
End Bearing Design in RockEnd Bearing Design in Rock
Only designed when • Dry Hole• Base Cleaning & Inspection are possible
Pile Capacity Design Pile Capacity Design Block CapacityBlock Capacity
Qu = 2D(B+L) s + 1.3(sb.Nc.B.L)Where Qu= ultimate bearing capacity of pile groupD = depth of pile below pile cap levelB = width of pile groupL = length of pile groups = average cohesion of clay around groupsb = cohesion of clay beneath groupNc= bearing capacity factor = 9.0 (Refer to Text by Tomlinson, 1995)
Pile Capacity DesignPile Capacity DesignBlock Block Capacity:InCapacity:In Cohesive SoilCohesive Soil
No risk of group failure
if FOS of individual pile is adequate
Pile Capacity DesignPile Capacity DesignBlock Capacity:Block Capacity: In In CohesionlessCohesionless SoilSoil
No risk of block failure
if the piles are properly seated in the rock
formation
Pile Capacity DesignPile Capacity DesignBlock Capacity:Block Capacity: On RockOn Rock
Pile Capacity Design Pile Capacity Design Negative Skin Friction (NSF)Negative Skin Friction (NSF)
Compressible soil layer consolidates with time due to:
Surcharge of fillLowering of groundwater table
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
Clay
FillOGL
1 2 30
Hf
ρsMonth
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
Pile to length (floating pile)Pile settles with consolidating soil NO NSF
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
Pile to set at hard stratum (end-bearing pile)
Consolidation causes downdrag forces on piles as soil settles more than the pile
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
Load
Load
Friction Pile –
Excessive Settlement
Load
End-Bearing Pile –
Crushing of Pile!!!
Positive Skin Friction
Pile Settlement >
Soil SettlementSoil Settlement > Pile Settlement
Negative Skin FrictionNegative Skin Friction
Negative
Skin
Friction
WARNING:No free fill by the contractor to avoid NSF
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
Effect of NSF Effect of NSF ……
Effect of NSF Effect of NSF ……
Reduction of Pile Carrying Capacity
NSF Preventive MeasuresNSF Preventive Measures
Avoid Filling
Carry Out Surcharging
Sleeve the Pile Shaft
Slip Coating
Reserve Structural Capacity for NSF
Allow for Larger Settlements
Clay
Sand
OGL
Qba
Qneg
SandFL
Clay
Sand
OGL
Qba
Qsu
Qall = (Qsu/1.5 + Qbu/3.0) - Qneg
Qsu
Qall = (Qsu/1.5 + Qbu/3.0)
Pile Capacity DesignPile Capacity DesignNegative Skin FrictionNegative Skin Friction
70 60 50 40 30 20 10 0
Settlement (mm)100 0 -100 -200-300-400-500-600 -700 -800 -900-1000
Axial Compression Force (kN)
Settlement Curves &Axial Compression Force
14 May 9815 May 9818 May 9821 May 9804 Jun 9809 Jun 9819 Jun 9802 Jul 9813 Jul 98
0 10 20 30 40 50SPT-N (Blows/300mm)
BoreholeBH-1BH-2
Datum = 36.300m
40
35
30
25
20
15
10
5
0
Dep
th (m
, bgl
)
Increased Pile Axial LoadIncreased Pile Axial Load
Check: maximum axial load < structural pile Check: maximum axial load < structural pile capacitycapacity
Pile Capacity Design Pile Capacity Design Negative Skin FrictionNegative Skin Friction
Maximum axial load
Allowable working loadQult
FOS
Pile Capacity DesignPile Capacity DesignFactor of Safety (FOS)Factor of Safety (FOS)
Allowable working load
Qult
FOS(Qneg + etc)
Without Negative Skin Friction:
With Negative Skin Friction:
Pile Capacity DesignPile Capacity DesignStatic Pile Load Test (Piles with NSF)Static Pile Load Test (Piles with NSF)
• Specified Working Load (SWL) = Specified foundationload at pile head
• Design Verification Load (DVL) = SWL + 2 Qneg
• Proof Load: will not normally exceed
DVL + SWL
Pile Settlement DesignPile Settlement Design
Pile Settlement DesignPile Settlement DesignIn Cohesive SoilIn Cohesive Soil
Design for Design for total settlement & settlement & differential settlement for design settlement for design tolerancetoleranceIn certain casesIn certain cases, total settlement not an settlement not an issueissueDifferential settlement can cause settlement can cause damage to structuresdamage to structures
Pile Group Settlement in Clay
=
Immediate / Elastic Settlement + Consolidation
Settlement
Pile Settlement DesignPile Settlement DesignIn Cohesive SoilIn Cohesive Soil
Where
pi = average immediate settlement
qn= pressure at base of equivalent raft
B = width of the equivalent raft
Eu= deformation modulus
μ1, μ0= influence factors for pile group width, B at depth D
below ground surface
by by JanbuJanbu, , BjerrumBjerrum and and KjaernsliKjaernsli (1956)(1956)
IMMEDIATE SETTLEMENTIMMEDIATE SETTLEMENT
Pile Settlement DesignPile Settlement DesignIn Cohesive SoilIn Cohesive Soil
u
ni E
Bqp 01μμ=
μ1
μ0
Influence factors (after Janbu, Bjerrum and Kjaernsli, 1956)
IMMEDIATE SETTLEMENTIMMEDIATE SETTLEMENT
Pile Settlement DesignPile Settlement DesignIn Cohesive SoilIn Cohesive Soil
As per footing (references given later)
CONSOLIDATION SETTLEMENTCONSOLIDATION SETTLEMENT
Pile Settlement DesignPile Settlement DesignIn Cohesive SoilIn Cohesive Soil
No risk of excessive settlement
Pile Settlement DesignPile Settlement DesignOn RockOn Rock
Allowable Settlement of Allowable Settlement of BuildingBuilding
Settlement of high-rise building < 12mm or 25mm?
Myth or fact?
Actual Building SettlementActual Building Settlement
Actual recorded settlement of high-rise building– 20mm to 125mm
Important design considerations – NOT total settlement – Differential settlement governs
Definitions of foundation movement
Economical Design Economical Design of Highof High--Rise FoundationRise Foundation
Clause 2.3.2.4.3, BS8004 – Wind loading– …… foundations may be so
proportioned that the pressure due to combined dead load, live and wind loads does not exceed the allowable bearing pressure by more than 25%
FOUNDATION FOUNDATION CONSTRUCTIONCONSTRUCTION
Part 2
Pile Installation Methods
PILE INSTALLATION PILE INSTALLATION METHODSMETHODS
•Diesel / Hydraulic / Drop HammerDriving
•Jacked-In
•Prebore Then Drive
•Prebore Then Jacked In
•Cast-In-Situ Pile
Diesel Drop Hammer Driving
Diesel Drop Hammer Diesel Drop Hammer DrivingDriving
Hydraulic Hammer Driving
Hydraulic Hammer Hydraulic Hammer DrivingDriving
JackedJacked--In In PilingPiling
JackJack--in Pilesin Piles
Cast-In-Situ Piles
(Micropiles)
CastCast--InIn--Situ Situ Piles Piles
((MicropilesMicropiles))
Types of Piles
TYPES OF PILESTYPES OF PILES
•Treated Timber Piles
•Bakau Piles
•R.C. Square Piles
•Pre-Stressed Concrete SpunPiles
•Steel Piles
•Boredpiles
•Micropiles
•Caisson Piles
R.C. Square PilesR.C. Square Piles
Size : 150mm to 400mmLengths : 3m, 6m, 9m and 12mStructural Capacity : 25Ton to 185TonMaterial : Grade 40MPa ConcreteJoints: WeldedInstallation Method :
–Drop Hammer–Jack-In
RC RC Square Square PilesPiles
Pile MarkingPile Marking
Pile LiftingPile Lifting
Pile Fitting to Piling MachinePile Fitting to Piling Machine
Pile Pile PositioningPositioning
Pile JoiningPile Joining
Considerations in Using RC Considerations in Using RC Square Piles Square Piles ……
•Pile Quality
•Pile Handling Stresses
•Driving Stresses
•Tensile Stresses
•Lateral Loads
•Jointing
PrePre--stressed Concrete Spun stressed Concrete Spun PilesPiles
Size : 250mm to 1000mmLengths : 6m, 9m and 12m (Typical)Structural Capacity : 45Ton to 520TonMaterial : Grade 60MPa & 80MPa ConcreteJoints: WeldedInstallation Method :
–Drop Hammer–Jack-In
Spun PilesSpun Piles
Spun Piles Spun Piles vsvs RC Square Piles RC Square Piles Spun Piles have …
•Better Bending Resistance
•Higher Axial Capacity
•Better Manufacturing Quality
•Able to Sustain Higher Driving Stresses
•Higher Tensile Capacity
•Easier to Check Integrity of Pile
•Similar cost as RC Square Piles
Steel H PilesSteel H Piles
Size : 200mm to 400mLengths : 6m and 12mStructural Capacity : 40Ton to 1,000TonMaterial : 250N/mm2 to 410N/mm2 SteelJoints: WeldedInstallation Method :
–Hydraulic Hammer–Jack-In
Steel H Steel H PilesPiles
Steel H Piles (ContSteel H Piles (Cont’’d)d)
Steel H Piles NotesSteel H Piles Notes……
•Corrosion Rate
•Fatigue
•OverDriving
OverDrivingOverDrivingof Steel Pilesof Steel Piles
Large Diameter CastLarge Diameter Cast--InIn--Situ Situ Piles (Bored Piles)Piles (Bored Piles)
Size : 450mm to 2m (Up to 3.0m for special case)Lengths : VariesStructural Capacity : 80Ton to 2,300TonsConcrete Grade : 20MPa to 35MPa (Tremie)Joints : NoneInstallation Method : Drill then Cast-In-Situ
Overburden Soil Layer
Bedrock
Drilling BorepileBorepile ConstructionConstruction
Overburden Soil Layer
Bedrock
Advance Drilling BorepileBorepile ConstructionConstruction
Overburden Soil Layer
Bedrock
Drilling & Advance Casing
BorepileBorepile ConstructionConstruction
Overburden Soil Layer
Bedrock
Drill to Bedrock BorepileBorepile ConstructionConstruction
BorepileBorepile ConstructionConstruction
Overburden Soil Layer
Bedrock
Lower Reinforcement Cage
Overburden Soil Layer
Bedrock
BorepileBorepile ConstructionConstructionLower TremieChute
Overburden Soil Layer
Bedrock
Pour TremieConcrete
BorepileBorepile ConstructionConstruction
BorepileBorepile ConstructionConstruction
Overburden Soil Layer
Bedrock
Completed Borepile
BORED PILING MACHINEBORED PILING MACHINEBored Pile Construction
BG22
Cleaning Bucket
Rock Reamer Rock Auger
Harden Steel
Rock Chisel
DRILLING EQUIPMENTDRILLING EQUIPMENTBored Pile Construction
Soil augerCoring bucketCleaning
bucket
BENTONITE PLANTBENTONITE PLANTBored Pile Construction
MixerWater Tank Slurry
Tank
DesandingMachine
DrillingDrilling
Lower Lower ReinforcementReinforcement
Place Place TremieTremie
ConcreteConcrete
Completed Completed BoredpileBoredpile
BorepileBorepile CosiderationsCosiderations……
•Borepile Base Difficult to Clean
•Bulging / Necking
•Collapse of Sidewall
•Dispute on Level of Weathered Rock
MicropilesMicropiles
Size : 100mm to 350mm DiameterLengths : VariesStructural Capacity : 20Ton to 250TonMaterial : Grade 25MPa to 35MPa Grout
N80 API Pipe as ReinforcementJoints: NoneInstallation Method :
–Drill then Cast-In-Situ–Percussion Then Cast-In-Situ
CastCast--InIn--Situ Situ PilesPiles
((MicropilesMicropiles))
TYPES OF PILE SHOESTYPES OF PILE SHOES
•Flat Ended Shoe
•Oslo Point
•Cast-Iron Pointed Tip
•Cross Fin Shoe
•H-Section
Cross Fin ShoeCross Fin Shoe
Do more harm in inclined rock surface!
Oslo Point ShoeOslo Point Shoe
Cast Iron Tip ShoeCast Iron Tip Shoe
Do more harm in inclined rock surface!
HH--Section ShoeSection Shoe
Do more harm in inclined rock surface!
Piling Supervision
Uniform Building By Uniform Building By Law (UBBL)1984Law (UBBL)1984
PILING SUPERVISIONPILING SUPERVISION•Ensure That Piles Are Stacked Properly
•Ensure that Piles are Vertical During Driving
•Keep Proper Piling Records
•Ensure Correct Pile Types and Sizes are Used
•Ensure that Pile Joints are Properly Welded withNO GAPS
•Ensure Use of Correct Hammer Weights and DropHeights
PILING SUPERVISION PILING SUPERVISION (Cont(Cont’’d)d)
•Ensure that Proper Types of Pile Shoes are Used.
•Check Pile Quality
•Ensure that the Piles are Driven to the RequiredLengths
•Monitor Pile Driving
FAILURE OF PILING FAILURE OF PILING SUPERVISIONSUPERVISION
Failing to Provide Proper Supervision
WILL Result in
Higher Instances of Pile Damage
& Wastage
Pile Damage
Driven concrete piles are vulnerable Driven concrete piles are vulnerable to damages by overdriving. to damages by overdriving.
Damage to Timber PileDamage to Timber Pile
Weak Weak Timber Timber JointJoint
Damage To RC Pile ToeDamage To RC Pile Toe
Damage to Damage to RC Pile RC Pile HeadHead
Damage to Damage to RC PilesRC Piles
Damage to RC Piles Damage to RC Piles –– contcont’’d d
Tilted RC Tilted RC PilesPiles
Damage to Steel PilesDamage to Steel Piles
Damaged Steel Pipe PilesDamaged Steel Pipe Piles
Detection of Pile Damage Detection of Pile Damage Through Piling RecordsThrough Piling Records
Piling Problems
Piling Problems – Soft Ground
Ground heave due to pressure relief at base &
surcharge near excavation
Pile tilts & moves/walks
Piling Problems – Soft Ground
Piling Problems – Soft Ground
Piling in Kuala Lumpur LimestonePiling in Kuala Lumpur Limestone
Important Points to Note:• Highly Irregular Bedrock Profile
• Presence of Cavities & Solution Channels
• Very Soft Soil Immediately Above Limestone Bedrock
Results in …• High Rates of Pile Damage
• High Bending Stresses
Piling Problems in Typical Limestone Piling Problems in Typical Limestone BedrockBedrock
Piling Problems Piling Problems –– Undetected Undetected ProblemsProblems
Piling Problems Piling Problems – Coastal Alluvium
Piling Problems Piling Problems –– Defective PilesDefective Piles
Seriously damaged pile due to severe driving stress in soft ground (tension)
Defect due to poor workmanship of pile casting
Defective pile shoe
Problems of defective pile head & overdriving!
Piling Problems Piling Problems –– Defective PilesDefective Piles
Cracks& fractured
Non-chamfered corners
Piling Problems Piling Problems –– Defective PilesDefective Piles
Pile head defect due to hard driving or and poor
workmanship
Piling Problems Piling Problems –– Defective PilesDefective Piles
Piling Problem - Micropiles
Sinkholes caused by installation method-
dewatering?
Piling in Fill GroundPiling in Fill GroundImportant Points to Note:
•High Consolidation Settlements If Original Ground is Soft•Uneven Settlement Due to Uneven Fill Thickness•Collapse Settlement of Fill Layer If Not Compacted Properly
Results in …•Negative Skin Friction (NSF) & Crushing of Pile Dueto High Compressive Stresses
•Uneven Settlements
Typical Design and Typical Design and Construction Issues #1Construction Issues #1
Pile Toe Slippage Due to Steep Incline Bedrock
Use Oslo Point Shoe To Minimize Pile Damage
Issue #1
Solution #1
Pile Breakage on Inclined Pile Breakage on Inclined Rock SurfaceRock Surface
No Proper Pile Shoe
Extension PilePileJoint
First Contact B/W Toe and Inclined Rock
Toe “Kicked Off”on Driving
Pile Body Bends
Pile Joint Breaks
Pile Breakage on Inclined Pile Breakage on Inclined Rock SurfaceRock Surface
Continue “Sliding” of
Toe
Use Oslo Point Shoe to Minimize Use Oslo Point Shoe to Minimize DamageDamage
Design and Construction Design and Construction Issues #2Issues #2
Presence of Cavity
Detect Cavities through Cavity Probing then perform Compaction Grouting
Issue #2
Solution #2
Presence of CavityPresence of Cavity
Pile Sitting on Limestone with Cavity
Application of Building Load
Application of Building Load
Roof of Cavity starts to Crack …
Collapse of Cavity Roof
Pile Plunges !
Building Collapse
Design and Construction Design and Construction Issues #3Issues #3
Differential Settlement
Carry out analyses to check the settlement compatibility if different piling system is adopted
Issue #3
Solution #3
Piling in Progress
Differential Settlement of Foundation
Original House on Piles
Hard LayerSPT>50
Cracks!!
No pile
SettlementSoft
Layer
Link House Construction
Renovation: Construct
Extensions
Piles transfer Load to
Hard Layer
No Settlement
SAFETY of Original Building
Not Compromised
Piling in Progress
Eliminate Differential SettlementEliminate Differential Settlement
Hard LayerSPT>50
Soft Layer
Construct Extension with Suitable Piles
All Load transferred to Hard Layer – No Cracks!
Piling in Progress
Problem of Short PilesProblem of Short Piles
Hard LayerSPT>50
Soft Layer
Load from Original House transferred to Hard Layer
Cracks!!
Soft!
Load transferred to
Soft Layer, Extension still Settles
Construct Extensions with Short
Piles
Cracks at ExtensionCracks at Extension
Typical Design and Typical Design and Construction Issues #4Construction Issues #4
Costly conventional piling design – piled to set to deep layer in soft ground
-Strip footings / Raft
-Floating Piles
Issue #4
Solution #4
“Conventional” Foundation for Low Rise Buildings
Foundation for Low Rise Buildings (Soil Settlement)
Exposed Pile
Settlement
Settling Platform Detached from Building
Conceptual Design of Conceptual Design of FOUNDATION SYSTEMFOUNDATION SYSTEM
1. Low Rise Buildings :-(Double-Storey Houses)= Strip Footings or Raft or Combination.
2. Medium Rise Buildings :-= Floating Piles System.
Low Rise Buildings on Piled Raft/Strips
Strip / Raft System
Stiff Stratum
Hard Layer
Fill
25-30m
Soft Clay
Comparison
Strip System
Stiff Stratum
Hard Layer
Fill
25-30m
Soft Clay
Building on Piles Building on Piled Strips
Comparison (after settlement)Building on Piles Building on Piled Strips
Strip System
Stiff Stratum
Hard Layer
Fill
25-30m
Soft Clay
Advantages of Advantages of Floating Piles SystemFloating Piles System
1. Cost Effective.
2. No Downdrag problems on the Piles.
3. Insignificant Differential Settlement between Buildings and Platform.
Bandar Botanic
Bandar Botanic at Night
Typical Design and Typical Design and Construction Issues #5Construction Issues #5
Load test results far below predicted pile capacity
-Modifications to test set-up
-Change of pile installation method
-Adequate soil plug to prevent toe softening
Issue #5
Solution #5
Testing SetTesting Set--up Using Reaction up Using Reaction PilesPiles
Testing SetTesting Set--up up
Long reaction piles at close spacing used
Case histories:– Load tests using reaction piles give
ERRATIC results– Reference: Weele (1993)
≈ 1100kN
Tested using
anchor piles
≈ 2100kN
Tested using
kentledge
Approx. 2 times
smaller using
reaction piles!
Ref: A.F. van Weele, 1993
Reaction piles
Test pile
Zone of interaction
with test pile
Testing SetTesting Set--up up
Latest version of ASTM D1143Published April 2007
Testing SetTesting Set--upup
ASTM D1143– Clear distance of at least 5 times
the maximum diameter– Caution on factors influencing
results:“Possible interaction ……….from anchor piles……..”
Drilling to the Casing Tip Drilling to the Casing Tip to Form to Form ““Bored PileBored Pile””
Drilling to Form Drilling to Form ““Bored PileBored Pile””
Disturbance to soil at tip and surrounding the pile
Potential hydraulic/basal heave failure resulting in lower soil strength
Effect more severe for longer pile
Construction of Construction of ““Bored PileBored Pile””1. Install Permanent Steel
Casing to Pile Toe
2. Removal of Soil within Steel Casing to Toe of Casing
3. Installation of Reinforcement and Concreting
Drilling to Form Drilling to Form ““Bored PileBored Pile””
Pile behaviour COMPLICATED!
– Influenced by steel casing which behave like DRIVEN PILE
– Influenced by soil removal which behave like BORED PILE
SAND UPHEAVAL
AFTER 3 HRS
Zone of Weakened Soil due to Installation of Steel Casing using Vibro-hammer
Pressure from
Drilling Fluid
Pressure from Soil + Water
Pressure from Soil + Water > Pressure from
Drilling Fluid
Further Soil Disturbance –Magnitude of Disturbance?????
Probable causes of erratic and unpredictable pile capacities:
– Testing set-up using reaction piles– Drilling to the casing tip to form “bored pile”
Original Load TestOriginal Load Test– 1st Load Test – Failed at 90% of WL
After 32 days
– 2nd Load Test – Failed at 110% of WLAfter 94 days
Recommendations:
– Open-ended spun pile or steel pipe pile with adequate soil plug
– Use of impact hammer instead of vibro-hammer
– Trial piles for correlation between static load test and high strain dynamic load test
Result for Concreted
Pile
Result for Empty Casing
Pile performs satisfactorily
within acceptable settlement limits!!!
Settlement at 1WL = 12.5mm
Load Test Results at P52WLoad Test Results at P52W– Result for Empty Casing
1xWL: pile settlement= 20mm(residual settlement= 1mm)1.9xWL: pile settlement= 50mm(residual settlement= 3mm)
– Result for Cast Pile1xWL: pile settlement= 12.5mm(residual settlement= 1mm)2xWL: pile settlement= 33.4mm(residual settlement= 7mm)
The Pile is Stiffer after
Concreting !!
Larger Residual Settlement due to Disturbance from
RCD work !!
Load Test Results at P52WLoad Test Results at P52W
– Research by Ng et al., 2001:Elastic compression of large diameter bored piles:–½ PL/AE - Piles founded in soil–¾ PL/AE - Piles founded in rocks
Result for Concreted Pile
Piles founded in SOIL: ½ PL/AE
Piles founded in ROCK: 3/4 PL/AE
Settlement is in
accordance to
prediction!!
Depends on:– E – Elastic Modulus of Pile Material– A – Cross-sectional Area of Pile– L – Pile Length
Elastic Compression = f (PL / AE)
Therefore, after concreting of pile:- A increased significantly (composite E due to
steel and concrete reduced slightly)- Elastic compression will reduce
ELASTIC COMPRESSION OF PILEELASTIC COMPRESSION OF PILE
Pile Settlement CriteriaPile Settlement Criteria
Pile settlement criteria depends on– Pile Size– Pile Material (e.g. steel, concrete, etc.)– Pile Length
Unrealistic to adopt same settlement criteria (e.g. 12mm) for all piles (regardless of length, size, etc.)
Myths in Piling
MYTHS IN PILING #1MYTHS IN PILING #1
Dynamic Formulae such as Hiley’s Formula Tells us the Capacity of the Pile
Pile Capacity can only be verified by using:
(i) Maintained (Static) Load Tests
(ii)Pile Dynamic Analyser (PDA) Tests
Myth:
Truth:
MYTHS IN PILING #2MYTHS IN PILING #2
Pile Achieves Capacity When It is Set.
Myth:
Truth:
Pile May Only “Set” on Intermediate Hard Layer BUT May Still Not Achieve Required Capacity within Allowable Settlement.
MYTHS IN PILING #3MYTHS IN PILING #3
Pile settlement at 2 times working load must be less than certain magnitude (e.g. 38mm)
Myth:
Truth:
Pile designed to Factor of Safety of 2.0. Therefore, at 2 times working load:
Pile expected to fail unless capacity under-predicted significantly
Pile Capacity DesignPile Capacity DesignFactor of Safety (FOS)Factor of Safety (FOS)
GlobalGlobal factor of safety for total ultimate factor of safety for total ultimate capacitycapacity
Use 2.0 (typical)Use 2.0 (typical)
ΣQsu + Qbu
2.0Qall =
MYTHS IN PILING #4MYTHS IN PILING #4
Jack-in piles cannot be used for high-rise buildings or in limestone formation
Myth:
Truth:
Jack-in piles can be used for high-rise buildings and limestone formation
- With proper design and input from experienced geotechnical engineer
G&P Geotechnics Sdn Bhd
Site A
31-storey
G&P Geotechnics Sdn Bhd
Site B 45-storey
G&P Geotechnics Sdn Bhd
Site C
Target Completion Mid 2011
40 to 43-storey
ADVANCES IN FOUNDATION ADVANCES IN FOUNDATION DESIGNDESIGNPILED RAFT FOUNDATION
PILED RAFT FOUNDATIONPILED RAFT FOUNDATION
Using conventional approach where part of the superstructure load is transferred to the slab/pilecap in contact with the ground
At least 25% to 40% reduction of numbers of piles – depending on soil conditions
PILED RAFT FOUNDATIONPILED RAFT FOUNDATIONSettlement reducing piles/full piled raft
Piles introduced to control settlement
Piles required may be as little as 10% of conventional pile design
Refer to publications by Randolph, Poulos, Katzenbach, etc.
CASE HISTORIESCASE HISTORIES
MEDIUM RISE BUILDINGSMEDIUM RISE BUILDINGS
200mm x 200mm reinforced concrete (RC) square piles with pile length varying from 18m to 24m:
350mm x 700mm strips and 300mm thick raft
Foundation Design for
5-Storey Low Cost
Apartment
CSM01
CSM02
CSM03
CSM04
CSM05
CSM06
CSM07
CSM08
CSM09
CSM10
CSM11
CSM12
CSM13
CSM14
Legend:CSM – Settlement markers (14 Nos.)
Total of 14 numbers of precise settlement markersMonitored results up to 313 days
SETTLEMENT MONITORING
CSM02
-33.55 -13.9 13.9 33.55Distance (m)
807978777675747372717069686766656463626160
Set
tlem
ent (
mm
)
-33.55 -13.9 13.9 33.55
807978777675747372717069686766656463626160
CSM05
CSM10
CSM14Centreline
β = 1/2356
β = 1/17595
β = 1/1698
β = 1/13950
Settlement Profile Across Edge of Building
Maximum differential settlement: 27mmMaximum local angular distortion: 1/1215
COMPLETED APARTMENTCOMPLETED APARTMENT
2500 Ton Siloon Very Soft Marine Deposits
Foundations for Foundations for HighriseHighrise
Bistari Condominiums, KL.Alternative design has reduced the foundation cost by more than 50%, A saving of more than RM5 million. An Award of Merit (1998) was given by ACEM.
Fill / Alluvium
Concrete Raft
SUMMARYSUMMARY
Importance of Preliminary Study
Understanding the Site Geology
Carry out Proper Subsurface Investigation that Suits the Terrain & Subsoil
Selection of Suitable Pile
Pile Design Concepts
SUMMARYSUMMARY
Importance of Piling Supervision
Typical Piling Problems Encountered
Present Some Case Histories
FERRARI ‘S PITSTOP WAS COMPLETED BY 15 MECHANICS (FUEL AND TYRES) IN 6.0 SECONDS FLAT.
54 PEOPLE TOOK PART IN THIS CONCERTED ACROBATIC JUMP.