Site Investigation

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://http://www.gnpgroup.com.mywww.gnpgroup.com.my

CONTENTSCONTENTS1. INTRODUCTION2. OBJECTIVES3. SCOPE4. INTERPRETATION

5. DESIGN PARAMETERS

6. LABORATORY TESTS

JKR PROBEJKR PROBESPTSPT


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


Proton Iswara


Ferrari

OBJECTIVESOBJECTIVES

1) Illustrate the importance of interpretation

2) Show methods of compiling results and recognising errors


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


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



Cased hardened steel pointer of Cased hardened steel pointer of 25mm 25mm diadia. and 60. and 60oo cone.cone.

12mm 12mm diadia. HY . HY 55C steel rod55C steel rod

Prevent buckling during driving

5kg drop 5kg drop hammerhammer

22mm outer 22mm outer diadia. coupling. coupling

28

•• ApparatusApparatus


CONE PENETROMETER


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


•• 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


•• Typical test resultsTypical test results


Identifying Identifying localisedlocalised soft/weak or slip plane.soft/weak or slip plane.

•• ApplicationsApplications


Identifying nonIdentifying non--compliance fill.compliance fill.

TT

T = compaction lift

Allowable Bearing Capacity V.S. J.K.R. Dynamic Cone Penetration Resistance (After Ooi & Ting, 1975) ** Conditions applied



•• Comparison between JKR probe and SPTComparison between JKR probe and SPT


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


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)


Shear Strength In kPa

Dep

th F

rom

Gro

und

Sur

face

In M

eter



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


Standard Penetration Test (SPT)Standard Penetration Test (SPT)


63.5kg Hammer

760mmFree Fall

450mm

Split-Spoon Sampler

AW Rod



Driving Shoe

Split Barrel

•• OD = 50mm OD = 50mm •• ID = 35mm ID = 35mm •• Length ~ 650mmLength ~ 650mm

Split-Spoon Sampler


Seating drive

Test drive

SPTSPT--N ValueN Value


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)


Maximum blows to be applied In seating drive In test drive Soil 25 50 ‘Soft rock’ 25 100

BS1377: Part 9

Formation Level


CLAY

SAND

SILTY CLAY

Red

uced

Lev

el (f

t)



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)


PiezoconePiezocone ((CPTuCPTu))

PiezoconePiezocone ResultsResults


Nk = 11-19

Lunne & Kleven (1981)

Nkt = 15

Gue & Tan (2000)


Cone factors related to plasticity index of the clays (After Dobie & Wong, 1990)


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)


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


Vane Shear TestVane Shear Test

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



Dep

th (f

t)

Shear Strength (lb/ft2)

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)


Design ParametersDesign Parameters

LABORATORY TESTSLABORATORY TESTS

-- Why?Why?

-- Types of Tests!Types of Tests!

-- How?How?

-- Specifications?Specifications?(Load, Pressure, Time)(Load, Pressure, Time)


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) 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


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.

Consolidation SettlementConsolidation Settlement

CONSOLIDATION TEST RESULTS

Void Ratio

Cv m²/year

Coefficient of Volume Change

Mv X 10ˉ³ m² / KN


Dep

th (m

)


Compression Index

Coefficient of Consolidation, Ch m²/yr

Dep

th (m

)



NAVFA C DM7.1

Log time methodRoot time method


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

•• 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 = 0.02 WWnn –– 0.370.37

•• CCrr ≈≈

(0.1 to 0.2)*C(0.1 to 0.2)*Ccc

Coefficient of secondary compression, CCoefficient of secondary compression, C αα

•• CC αα

/ C/ Ccc = 0.04 = 0.04 ±±

0.010.01 For inorganic soft claysFor inorganic soft clays

•• CC αα

/ C/ C cc = 0.02 = 0.02 ±±

0.010.01 For granular soils including For granular soils including rockfillrockfill

•• CC αα

/ C/ C cc = 0.03 = 0.03 ±±

0.010.01 For shale and mudstoneFor shale and mudstone

•• CC αα

/ C/ C cc = 0.05 = 0.05 ±±

0.010.01 For organic clays and siltsFor organic clays and silts

•• CC αα

/ C/ C cc = 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


Conventional Foundation for Low Rise Buildings


Conventional Foundation for Low Rise Buildings (Soil Settlement)


Exposed Pile

Settlement

Settling Platform Detached from Building


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


Simple CheckSimple Check

qq allowallow = (= (NN cc ..ss uu / FOS)/ FOS)qq allowallow == allowable bearing pressure allowable bearing pressure

= = ((γγfillfill .H.H + 10) + 10) (( in kPain kPa))

NN cc == 55

HHfailurefailure = (5 x Su) / = (5 x Su) / γγ fillfill

e.g. :e.g. :When When Su = 10 kPa ; Su = 10 kPa ; γγfillfill = 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


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


Typical Set-up of Triaxial Test

a)Base

b)Removable cylinder and top cap

c)Loading ram

d)Rubber membrane

Equipment for Equipment for TriaxialTriaxial TestTest

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


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’


For Slopes & Walls AnalysesFor Slopes & Walls Analyses Parameter cParameter c’’ and and φφ’’ shall be shall be Interpreted fromInterpreted from

i)i) IsotropicallyIsotropically Consolidated Undrained Consolidated Undrained TriaxialTriaxial Test, CIU + Test, CIU + ΔΔuu

ii)ii)IsotropicallyIsotropically Consolidated Drained Consolidated Drained TriaxialTriaxial Test, CIDTest, 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


Large Strain


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


Correlations for Preliminary Assessment of φ’


φφ’’ Values Values vsvs Plasticity IndexPlasticity Index (after (after TerzaghiTerzaghi))

Typical PI = 30% to 70%(Malaysia Soft Clay)G&P Geotechnics Sdn Bhd

ΦΦ’’ Values Values vsvs Clay ContentClay Content ((SkemptonSkempton, 1964), 1964)


ΦΦ’’ vsvs % of Fines% of Fines

Figure 3 : φ’peak versus Percentage of Fines in Residual Soils

30

35

25


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


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


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


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


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