yantubbs-A-State-Parameter-for-Sands--Been-Jefferi

BEEN,K.&JEFFERIES,M.G.(1985).G&technique35,No.2,99-112AstateparameterforsandsK.BEEN*andM.G.JEFFERIEStTherequirementforarationalengineeringapproachtoconstructingstructuresusingundensifiedhydraulicsandfillhasidentifiedseveraldeficienciesincurrenttechnology.Inparticular,thereisnosingleparametermeasureofsandbehaviour.ThisPaperpresentsanappropriatephysicalparameter,termedthestateparameter,thatcombinestheinfluenceofvoidratioandstresslevelwithreferencetoanultimate(steady)statetodescribesandbehaviour.DatafromatriaxialtestingprogrammeonKogyuksandwithfourfinescontentsispresentedandthesignificantengineeringdesignparametersaredemonstratedtobedependentonthestateparameter.Theconceptofstateisafundamentalphysicalconceptandhaswideapplicabil-itybothasanempiricalnormaliz.ingparameterandforconstitutivemodellingofsoilbehaviour.simplesheartestmediangrainsizevoidratiomaximumandminimumvoidratiodeterminedbyASTMD2049meannormaleffectivestressorfirststressinvariant,(a,‘+~~‘+(TX’)/3I1oncompletionofconsolidationI,ontheSSLataparticularvoidratioPlusieursinsuffisancesdelateclmologiehabituelleontCttreveleeslorsqu’onatent6detrouverunemethodedeconstructionrationnellepouvant&treutilisedanslecasdestructureslikesal’emploideremblaishydrauli-quessableuxnon-compactes.Enparticulieriln’yapasdeparametreuniquepourmesurerlecomportementdusable.CZetarticlepresenteunparametrephysiqueadtquat(appeltparametred’itat)quicombinel’in-fluencedeI’indicedesvidesetduniveaudescon-traintesdanstm&tatfinal(stationnaire)pourd&irelecomportementdusable.Onpresentedesdonneesobtenues&partird’unprogrammed’essaistriaxiauxsurdusabledeKogynkavecquatrecontenusdifferemsdefines.Ondemontrecommentlesparametressignificatifsduprojetdependentduparamttred’etat.Lanotiond’ttatestunenotionphysiquefondamentalequiaunelargeapplicationcommeparametreempiriquedenormalisationetquipeuts’employerpourmodtliserlecomportementdutriaxialnormalstress,(a1+a,)/2shearstressintriaxialtest,(al-(+3)/2peakshearstressintriaxialteststeadystatelineporewaterpressureinitialporewaterpressurechangeinporepressure,u-u,,axialstrainvolumetricstrainslopeoftheSSL,-Ae/A(logI,)principaleffectivestresseseffectiveconsolidationpressureintriaxialtestsdrainedangleofshearingresis-tance4’ontheSSLstateparameter(seeFig.2)INTRODUCTIONExtensivetestingofKogyuksandfromtheCanadianBeaufortSeahasclearlydemonstratedthatthebulkcharacteristicsofsandsarenotsufhcienttocharacterizemechanicalbehaviourofgranularmaterials.Similarevidencecanbefoundinotherpublishedstudiesofsandproper-ties(e.g.Lee,1965;Lade,1972).Inparticular,confiningpressuremodifiesmaterialbehaviourofsandstothepointthatevendensesand,iftestedatsufhcientlyhighconfiningpressure,willbehavesimilarlytoloosesand.Therefore,prop-ertiesofsandscannotbeexpressedintermsofrelativedensityalone;adescriptionofstresslevelmustalsobeincluded.sol.NOTATION-%BCAUCIDCIUSkempton’sporepressureparame-ter(Au/A(+r)atfailureSkempton’sporepressureparam-eterconsolidatedanisotropicallyun-drainedtriaxialtestconsolidatedisotropicallydrainedbiaxialtestconsolidatedisotropicallyun-drainedtriaxialtestDiscussiononthisPapercloseson1October1985.Forfurtherdetailsseeinsidebackcover.*GolderAssociates,Calgary.tGulfCanadaResources,Calgary.ThetestprogrammewascarriedoutaspartoftheengineeringforanArcticoffshoreexplora-tionstructureandconsistedlargelyofroutinetriaxialtestscarriedoutbycommerciallaboratories.Thetestsdemonstratedthatthe99100BEENANDJlSFFEFUESsamesandwithseveralsiltcontents,testedunderverydifferentcombinationsofvoidratioandmeaneffectivestress,behavessimilarlyiftestconditionsassureanequalinitialproximitytothesteadystate.Theproximitytothesteadystateisidentifiedasthe‘stateparameter’,whichisdefinedasthevoidratiodifferencebetweentheinitialsandstateandthesteadystatecondi-tionsatthesamemeaneffectivestress.Theprincipalresultofthisworkisthatitestablishesthatasingleparameter,thestateparameter,canbeusedtodescribemuchofthebehaviourofgranularmaterialsoverawiderangeofstressesanddensities.Whilethisdoesnoteliminatetheinfluenceofeitherdensityorconfiningpressureonthebehaviourofsands,itproperlyplacesemphasisonthefactthatitisacombinationoftheseparametersthatisphysi-callyrelevanttothedescriptionofgranularma-terials.Itisrecognizedthattheanisotropicfabricofsandhasnotbeenaccountedforinthecurrentwork.However,thestateparameterhasbeenusedtonormalizelargestrainbehaviourswheretheinfluenceofinitialfabricissmall.Aniso-tropicfabricisregardedasasecondparameterwhich,incombinationwiththestateparameter,willallowareasonablycompletedescriptionofsandbehaviouratbothsmallandlargestrains.BACKGROUNDExplorationdrillingforhydrocarbonsintheCanadianBeaufortSeahasbeencarriedoutprimarilyfromartificialsandislandsbecauseoflargeloadingscausedbytheprevailingenviron-mentalcondition:ice.Islandfillvolumesin-creasedramaticallyindeeperwaterandtheexplorationcompanieshavetriedtominimizeislandconstructioncoststhroughcaissontech-nology(deJong&Bruce,1978;Fitzpartick&Stenning,1983;Fitzpatrick,1983;Bruce&Harrington,1982).Theconceptistouseacais-sontoreducesubstantiallytheamountofsandfillina