G&P Geotechnics Sdn Bhd by by Ir. Dr. Gue See Sew & Ir. Chow Chee Meng Ir. Dr. Gue See Sew & Ir. Chow Chee Meng INTERPRETATION OF INTERPRETATION OF LABORATORY AND LABORATORY AND FIELD TEST RESULTS FIELD TEST RESULTS FOR DESIGN FOR DESIGN http:// http:// www.gnpgroup.com.my www.gnpgroup.com.my
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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
•• 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
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Standard Penetration Test (SPT)Standard Penetration Test (SPT)
G&P Geotechnics Sdn Bhd
63.5kg Hammer
760mmFree Fall
450mm
Split-Spoon Sampler
AW Rod
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G&P Geotechnics Sdn Bhd
Driving Shoe
Split Barrel
•• OD = 50mm OD = 50mm •• ID = 35mm ID = 35mm •• Length ~ 650mmLength ~ 650mm
Maximum blows to be applied In seating drive In test drive Soil 25 50 ‘Soft rock’ 25 100
BS1377: Part 9
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G&P Geotechnics Sdn Bhd
Formation Level
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CLAY
SAND
SILTY CLAY
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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)
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PiezoconePiezocone ((CPTuCPTu))
PiezoconePiezocone ResultsResults
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PiezoconePiezocone ResultsResults
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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)
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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)
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G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
1)1)Vane test in boreholeVane test in borehole
2)2) GeonorGeonor vanevane
3)3) Lab vaneLab vaneUseUse-- To determine inTo determine in--situ undrained situ undrained
shear strength (shear strength (SSuvuv ) of soft clayey ) of soft clayey soilssoils
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Vane Shear TestVane Shear Test
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Most common errorsMost common errors-- Computation Computation –– spring factorspring factor-- Clay with organic materialsClay with organic materialsRecogniseRecognise errorserrorsSummariseSummarise results with Sresults with Suu from from unconfined compression, UU and lab unconfined compression, UU and lab vane superimposedvane superimposedPlot Plot SSuvuv against PIagainst PI
PPoo’’Or Or SSuvuv 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)
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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)
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) B) TriaxialTriaxial testtest1) 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
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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 CONT ENT
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. - Mult i-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.
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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
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Dep
th (m
)
G&P Geotechnics Sdn Bhd
Compression Index
Coefficient of Consolidation, Ch m²/yr
Dep
th (m
)
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G&P Geotechnics Sdn Bhd
G&P Geotechnics Sdn Bhd
NAVFA C DM7.1
Log time methodRoot time method
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Compression index, CCompression index, C cc and and Recompression index, CRecompression index, C rra) a) CC cc = 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) CC cc = 0.007 (LL = 0.007 (LL –– 10%)10%) For normally For normally consolidated clayconsolidated clay
c) c) CC cc = 0.0115 = 0.0115 WW nn For organic soils, peatFor organic soils, peat
d) d) CC cc = 1.15 (= 1.15 (ee oo –– 0.35)0.35) For all claysFor all clays
e) e) CC cc = (1 + = (1 + ee oo ) [0.1 + () [0.1 + (WW nn –– 25)0.006]25)0.006] For For varvedvarved claysclays
f) f) CC cc = 0.5*PI*G= 0.5*PI*G ss For OC claysFor OC clays
Compression index, CCompression index, C cc and and Recompression index, CRecompression index, C rr
Figure 3 : φ’peak versus Percentage of Fines in Residual Soils
30
35
25
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cc’’ vsvs % of Fines% 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, field vane, piezoconepiezocone, etc., etc.
YOU PAY FOR YOU PAY FOR SOIL SOIL INVESTIGATIONINVESTIGATION WHETHER 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
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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
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