Anisotropic shear strength model for clay.pdf

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1、INTERNATIONALJOURNALFORNUMERICALANDANALYTICALMETHODSINGEOMECHANICSInt.J.Numer.Anal.Meth.Geomech.(2011)PublishedonlineinWileyOnlineLibrary(wileyonlinelibrary.com).DOI:10.1002/nag.1016NGI-ADP:AnisotropicshearstrengthmodelforclayGustavGrimstad∗,,LarsAndresenandHansP.Jostad

2、NorwegianGeotechnicalInstitute,NGI,Oslo,NorwaySUMMARYManygeotechnicalproblemsinvolveundrainedbehaviorofclayandthecapacityinundrainedloading.Mostconstitutivemodelsusedtodayareeffectivestressbasedandonlyindirectlyobtainvaluesfortheundrainedshearstrength.Tomatchthedesignpr

3、ofilesofundrainedshearstrengths,inactive(A),directsimpleshear(D)andpassive(P)modesofloadingarecomplicated.ThispaperpresentstheelastoplasticconstitutivemodelNGI-ADPwhichisbasedontheundrainedshearstrengthapproachwithdirectinputofshearstrengths.Consequently,exactmatchwithde

4、signundrainedshearstrengthsprofilesisobtainedandthewell-knownanisotropyofundrainedshearstrengthandstiffnessisaccountedforintheconstitutivemodel.Anon-linearstresspath-dependenthardeningrelationshipisused,definedfromdirectinputoffailurestrainsinthethreedirectionsofshearingr

5、epresentedbytriaxialcompression,directsimpleshearandtriaxialextension.Withitsclearinputparametersthemodelhassignificantadvantagesfordesignanalysisofundrainedproblems.Theconstitutivemodelisimplemented,intofiniteelementcodes,withanimplicitintegrationscheme.Itsperformanceisd

6、emonstratedbyafiniteelementanalysisofabearingcapacityproblem.Copyright2011JohnWiley&Sons,Ltd.Received18January2010;Revised6September2010;Accepted24November2010KEYWORDS:clay;anisotropy;undrainedshearstrength1.INTRODUCTIONAlargeclassofgeotechnicalproblemsmaybeclassifiedasu

7、ndrained,meaningthattherateofloadingand/orthelowpermeabilityofthesoilpreventanysignificantporepressuredissipationduringthetimeofinterest,e.g.constructiontimeortimegoverningthefailureprocess.Theseproblemsmaybeanalyzedusingtheundrainedshearstrengthapproachassuggestedbye.g.

8、Skempton[1]orLadd[2]andusedinengineeringpracticeatNGI.Theundrainedstressstrainstrengthresponseofsoftclaysisgen