pengujian tanah laboratorium dan lapangan si-5122 semester i 2012 2013

7/30/2019 Pengujian Tanah Laboratorium dan Lapangan SI-5122 SEMESTER I 2012 2013

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PhysicalandHydraulic

PropertiesofSoilsGravels,Sands Silts Clays

Grainsize: Coarse grained

Canseeindividual

grainsbyeye

Finedgrained

Cannot see

individualgrains

Finegrained

Cannotsee

individualgrains

Characteristics: Cohesionless

Nonplastic

Granular

Cohesionless

Nonplastic

Granular

Cohesive

Plastic

Effectofwateron

engineering

behavior:

Relatively

unimportant

(exception: loose

saturatedgranular

materialsand

dynamicloadings)

Important Important

Effectofgrain size

distributionon

engineering

behavior:

Important Relatively

unimportant

Relatively

unimportant

2


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RoleofClassificationSystemin

GeotechnicalEngineeringPractice

ClassificationandIndexProperties

(w,e,,GSD,LL,PI,etc.)

ClassificationSystem

(USCS,British,etc.)

EngineeringProperties

(permeabilities,compressibility,shrinkswell,shear

strength,etc.)

EngineeringPurpose

(highways,airfields,foundations,dams,etc.)

3

Liquid Limit, %

0 10 20 30 40 50 60 70 80 90 100

PlasticityIndex,%

0

10

20

30

40

50

60

CL

CH

ML or OL

Micaceous or diatomaceous finesandy and silty soils;elastic silts; organic silts, clays, andsilty clays

OH or MH

A-lin

e

U-lin

e

ML

CL-ML

Inorganic and organic siltsand silty clays of lowplasticity; rock flour; siltyor clayey fine sands

In organic clays ofhigh plasticity

Mediumplasticinorganicclays

Low plastic inorganicclays; sandy andsilty clays

Silty clays;clayey siltsand sands

Characteristics EqualLLincreasing PI EqualPIincreasing LLDryStrength Increases Decreases

ToughnessnearPL Increases Decreases

Permeability Decreases Increases

Compressibility Aboutthesame Increases4


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StrengthParameters

CohesiveSoils

TotalStressAnalysisMethod

UndrainedShearStrength(UnconsolidatedUndrainedorConsolidatedUndrainedTriaxialTest,FieldVaneShearTest)

EffectiveStressMethod

InternalFrictionAngle(ConsolidatedDrainedorConsolidatedUndrainedTriaxialTestwithporewatermeasurement)

Effectivecohesion(ConsolidatedDrainedorConsolidatedUndrainedTriaxialTestwithporewatermeasurement)

CohesionlessSoils Internalfrictionangle(DirectShearTest,estimatedfromfieldtests)

5

CompressibilityandConsolidation

Parameters

CohesiveSoils

ElasticDeformation

UndrainedDeformationModulus,Eu

PoissonsRatio, ConsolidationSettlement

CompressionIndex,Cc;RecompressionIndex,Cr

InitialVoidRatio,eo PreconsolidationPressure,Pc; OCR(Overconsolidation Ratio)

CohesionlessSoils

DeformationModulus,E

PoissonsRatIo,

6


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RiskBasedFlowChartforSite

Characterization

7

InSituTests

Reference/Manual:

ASTMD420SiteCharacterizationforEngineeringDesignandConstructionPurposes

ManualonSubsurfaceInvestigations NationalHighwayInstitute

PublicationNo.FHWANHI01031

FederalHighwayAdministration

Washington,DC GeotechnicalSiteCharacterization July2001

byPaulW.Mayne,BarryR.Christopher,andJasonDeJong8


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InSituTests

Theobjectivesofanysubsurfaceinvestigationaretodeterminedthefollowing:

Natureandsequenceofthesubsurfacestrata

Groundwaterconditions

Physicalandmechanicalpropertiesofthe

subsurface

strata

9

InSituTests

Theapplicabilityandusefulnessofinsitutests(Lunne,Robertson&Powell,2007):

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InSituTestMethods

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ConePenetrationTest(CPT)

Advantages:

Fastandcontinuousprofiling

Repeatableandreliabledata(notoperatordependent)

Economicalandproductive

Strongtheoreticalbasisforinterpretation

Disadvantages:

Highcapitalinvestment(forpiezoconeCPTUandseismicSCPT) Requiresskilledoperators

Nosoilsample

Penetrationcanberestrictedingravel/cementedlayers

12


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StandardPenetrationTest(SPT)

SPT is used as an indicator of relative density and stiffness of granularsoils as well as an indicator of consistency of other ground. SPT isapplied in a wide range of geotechnical application including shallow anddeep foundation and the assessment of liquefaction potential

Advantages:

Simpleandrugged

Lowcost

Obtainasample

Canbeperformedinmostsoiltypes

Disadvantages:

Disturbed

sample

(index

tests

only) Crudenumber(Nvalue)

Notapplicableinsoftclaysandsilts

Highvariabilityanduncertainty

13

FieldVaneShearTest(FVST)

FVSTisusedtoevaluatetheundrainedshearstrength,suv,ofsofttostiffclaysandsilts.Bothpeakandremoldedstrengthscanbemeasuredandtheirratioistermedsoilsensitivity(St)

Advantages:

Simpletestandequipment

Longhistoryofuseinpractice

Disadvantages:

Limitedapplicationtosofttostiffclaysandsilts

Slowandtimeconsuming

Rawsuv valuesneed(empirical)correction

Canbeaffectedbysandlensesandseams

14


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Pressuremeter Test(PMT)

PMTcanbeusedtoevaluatethestressstrainresponseofawiderangeofsoilsandrock

Advantages:

Strongtheoreticalbasisforinterpretation

Testslargevolumeofground

Disadvantages:

Complicatedequipmentandprocedures

Requiresskilledoperator

Timeconsumingandexpensive

Equipmentcanbeeasilydamaged

15


16

BegemannTypeConewithFrictionSleeve

VariousConePenetrometerincludingElectricFrictionandPiezocone Types


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2)1( uaqq ncT an =netarearatiodeterminedfromcalibrationofthe

coneinatriaxialchamber.

Formost10cm2 Penetrometer:0.75


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CPTInterpretation

19

CPTInterpretation

SoilProfilingandClassification

NonnormalizedChart

Mostcommonlyusedsoilbehaviortype(SBT)method(Robertsonetal.,1986)

Useconeresistanceandfrictionratio

Forsoundingupto20meterindepth

NormalizedChart

CPTreadingsmustbecorrectedforoverburdenstressespeciallyfortheveryshallowandverydeepsoundings

Robertsonetal.,1990SBTcharts

20


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CPTInterpretation

SoilBehaviorType(Robertsonetal.1986)

21

CPTInterpretation

NormalizedSoilBehaviorType(Robertsonetal.1990)

22


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CPTInterpretation

SoilBehaviorTypeIndex,Ic

23

CPTInterpretation

EquivalentSPTN60

24Robertson,etal.,1983


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CPTInterpretation

EquivalentSPTN60

25

FornonnormalizedCPTChart(Robertsonetal.,1986)

CPTInterpretation

26

GeotechnicalParameters

UndrainedShearStrength

SoilSensitivity,St

kt

vTu

N

qs

Nkt =10 20(15asanaverage)

Plasticity NktSensitivity Nkt

skt

vT

remoldedu

ut

fN

q

s

sS

1

.


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CPTInterpretation

27


Overconsolidation Ratio

''

'

vo

vT

vo

p qkOCR

k =0.2 0.5(0.3isrecommended)

Formoderatetohighriskprojectsitespecificcorrelationwith

laboratoryOCRishighlyrecommended

CPTInterpretation

28


InsituStressRatio,Ko

'1.0

vo

vTo

qK

Kulhawy andMayne (1990)

Formechanicallyoverconsolidated soilsnotforcementedsoils

Note:CPTisnotareliablemethodtodetermineKo


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CPTInterpretation

29


InsituStressRatio,Ko

Andresenetal.(1979)

CPTInterpretation

30


FrictionAngleofuncemented,unaged,moderatelycompressible,predominantlyquartzsands(RobertsonandCampanella,1983)


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CPTInterpretation

31


StiffnessandModulus

Recentfillwithanageless

than10years

Naturalsandswithanage

greaterthan100years

CPTApplication

32


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ASTMD1586

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34


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FactorsAffectingSPT

Drillingandboreholetechnique

Methodofboreholeadvancement(washboring,coring,percussiondrilling)

Methodofboreholesupport(casingorbentonite slurry)

Sizeofborehole(55 150mm)

SPTequipment

Hammerdesign

Rodsizeandtype

Samplerdesign(withorwithoutliner)

TestProcedure

Seatingdrive(6inches=15cm)

Methodofmeasurement(DeliveredenergyisnotlinearwhenSPT>50)

Rateofhammerblows(30 40blows/minute)

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SPTHammerTypes

37

Automatictrippingmechanism

RecommendedSPTTestProcedure

38


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FactorsAffectingSPTInterpretation

Energydelivered

Energyrodratio(ER)variesbetween20 100%

NormalizedtoERof60%

Overburdenstress

Penetrationresistanceincreaseswithincreasingoverburdenpressure

Normalized

to

equivalent

value

at

an

effective

overburden

pressureof1atm (1tsf =100kPa)

Groundconditions39

measured

fN

EN

6060


GroundConditions

Granularsoils

Horizontalstressandstresshistory

Graincharacteristics

Ageandcementation

Drainage

Cohesivesoils

Stresshistory

Sensitivity SoilStructure

Weakandweatheredrocks

Spacingofjoints

Weathering

Hardinclusions40


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41

IllustrationofVariationinSPTEnergyRatio

SPT Energy

Measurement

SPTCorrectionFactors

42


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SPTInterpretation

Generallyrestrictedtocleancohesionlesssoilswherepenetrationtakesplaceunderdrainedconditions. Howevercorrelationshavebeendevelopedforawiderangeofground

43

SPTInterpretation

RelativeDensity

FrictionAngle

StiffnessandModulus


StressHistory

Compressibility

44


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SPTInterpretation

RelativeDensity

45

SPTInterpretation

FrictionAngle

46DeMello(1971)

Hatanaka &Uchida(1996):


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SPTInterpretation

StiffnessandModulus

47

>1000yearsofage


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SPTInterpretation


49

Laddetal.(1977):

UseSPTvs UndrainedShear

Strengthforrelativelystiffand

insensitiveclays

SPTInterpretation

StressHistory(OCR)

50Kulhawy andMayne (1990)


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SPTApplications

51

FieldVaneShearTest

ASTMD2573

52


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FVSTEquipment

53

FVSTBladeSizeandDimension

54


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FVSTInterpretation


Assumeduniformstressdistributionoftopandbottomandalongthebladesandavanewithaheighttowidthratio,H/D=2

Tmax =maximumtorque

55

3

max

7

6

D

Tsuv

FVSTInterpretation

Sensitivity

Afterthepeakstrengthisobtainedthevaneisrotatedquickly10completerevolutionsandthetestrepeatedtomeasuretheremoldedstrength

56

remoldeduv

peakuv

t s

s

S (

)(


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FVSTInterpretation

CorrectionFactor

ItiscommontocorrectFVSTvaluepriortotheapplicationinstabilityanalysisofembankmentonsoftsoils,bearingcapacityandexcavationinsoftground

57

uvRmobilized s

5.005.1 PIbR

(minute)failuretotime

factorratea

log0075.0015.0

f

f

t

b

tb

Chandler,1988

Pressuremeter Test(PMT)

ASTMD4719

58


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PMTEquipmentandProcedure

59

PMTInterpretation

IndexParameters

LimitPressure,PL NetLimitPressure,PL

*=PL Po Atresttotalstress

60

tcoefficienpressureearthlateral

pressureporechydrostati

surfacegroundbelowdepth

densitybulk

o

oo

K

u

z

uKuzP


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PMTInterpretation

Pressuremeter Modulus

Fromelastictheoryforradialexpansionofa

cylindricalcavity:

61

cavityin thepressure

cavitytheofvolumethe

modulusshearthe

P

V

G

V

PVG

PMTInterpretation

Pressuremeter Modulus

UsevolumeVcorrespondingtothemidpointofthe

linearportionofthevolumepressurecurve,VPM

62

RatiosPoisson'

)1(2

)1(2

:ModulussYoung'

V

PVE

GE

V

PVG

PMPM

PMPM

PMPM


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PMTApplications

FoundationDesign

Endbearingcapacity(basesupport)

Netbearingcapacity

63

oL PPkq

*

kisacorrectionfactorwhichisdependentonsoil

type,depthofembedment,PL,andfoundationshape

PMTApplications

64

ValuesofkforFootingsandCastinplacePileTips


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PMTApplications

65


PMTApplications

66



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PMTApplications

67

ValuesofkforDrivenPiles

PMTApplications

68ValuesofkforDrivenPiles


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PMTApplications

69

Adhesion,

kPa

SideFrictionforPiles

LaboratoryTriaxialTests

UnconsolidatedUndrainedTriaxialTest

ConsolidatedDrainedTriaxialTest

ConsolidatedUndrainedTriaxialTestwithPoreWaterMeasurement

70


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UnconfinedCompressionTest

73

ConsolidatedUndrainedTriaxialTest

74Totalandeffectivestressfailureenvelopes


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StressPathofCUTriaxialTestfor

NormallyConsolidatedClays

75

StressPathofCUTriaxialTestfor

Overconsolidated Clays

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1. GuidetoConePenetrationTestingfor

GeotechnicalEngineering,P.K.Robertsonand

K.L.Cabal(Robertson),January2009

2. GuidetoInSituTesting,P.K.Robertson,

January2006

3. AnIntroductiontoGeotechnicalEngineering,

HoltzandKovacs(1981)

77

References

Thankyou

78

pengujian tanah laboratorium dan lapangan si-5122 semester i 2012 2013

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