CSSMforDummies临界状态土力学的讲座.ppt

2006,Critical-StateSoilMechanicsForDummies,PaulW.Mayne,PhD,P.E.Civiland(2)shearstress-vs.normalstress(t-sv)fromdirectshearboxorsimpleshearing.Herein,onlythebareessenceofCSSMconceptsarepresented,sufficienttodescribestrength1960,ASCE);Henkel(1960,ASCEBoulder)HenkelWood(1990).Inbasicform:3materialconstants(f,Cc,Cs)plusinitialstate(e0,svo,OCR)ConstitutiveModels,include:OriginalCam-Clay,ModifiedCamClay,NorSand,BoundingSurface,MIT-E3(Whittle,1993)&MIT-S1(Pestana)andothers(Adachi,Oka,Ohta,Dafalias)UndrainedisjustonespecificstresspathYet!CSSMismissingfrommosttextbooksandundergrad&gradcurriculaintheUSA.,One-DimensionalConsolidation,OverconsolidationRatio,OCR=3,Cs=swellingindex(=Cr)cv=coef.ofconsolidationD=constrainedmodulusCae=coef.secondarycompressionkhydraulicconductivity,sv,DirectShearTestResults,sv,DirectShearBox(DSB),CSSMforDummies,Logsv,Effectivestresssv,Shearstresst,VoidRatio,e,NC,CC,CSSMPremise:“Allstresspathsfailonthecriticalstateline(CSL)”,f,c=0,CSSMforDummies,Logsv,Effectivestresssv,Shearstresst,VoidRatio,e,VoidRatio,e,NC,NC,CC,tanf,CSL,CSL,STRESSPATHNo.1NCDrainedSoil,Given:e0,svo,NC(OCR=1),e0,svo,svo,DrainedPath:Du=0,tmax=c+stanf,VolumeChangeisContractive:evol=De/(1+e0)0,Effectivestresssv,Criticalstatesoilmechanics,Initialstate:e0,svo,andOCR=sp/svoSoilconstants:f,Cc,andCs(L=1-Cs/Cc)ForNCsoil(OCR=1):Undrained(evol=0):+Duandtmax=su=cuDrained(Du=0)andcontractive(decreaseevol)ForOCsoil:Undrained(evol=0):-Duandtmax=su=cuDrained(Du=0)anddilative(Increaseevol),Theresmore!,Semi-drained,Partlyundrained,Cyclic.,EquivalentStressConcept,Logsv,Stresssv,Shearstresst,VoidRatio,e,NC,NC,CC,tanf,CSL,CSL,CSL,CS,OC,1.OCState(eo,svo,sp),svo,2.ProjectOCstatetoNClineforequivalentstress,se,3.se=svoOCR1-Cs/Cc,Effectivestresssv,VoidRatio,e,sp,sp,se,su,De=Cslog(sp/svo)De=Cclog(se/sp),atsesuOC=suNC,Criticalstatesoilmechanics,Previously:su/svo=constantforNCsoilOnthevirgincompressionline:svo=seThus:su/se=constantforallsoil(NC&OC)Forsimpleshear:su/se=sinfEquivalentstress:,NormalizedUndrainedShearStrength:su/svo=sinfOCRLwhereL=(1-Cs/Cc),se=svoOCR1-Cs/Cc,UndrainedShearStrengthfromCSSM,UndrainedShearStrengthfromCSSM,PorewaterPressureResponsefromCSSM,YieldSurfaces,Logsv,Normalstresssv,Shearstresst,VoidRatio,e,NC,NC,CSL,CSL,CSL,OC,Normalstresssv,VoidRatio,e,sp,sp,OC,Yieldsurfacerepresents3-dpreconsolidationQuasi-elasticbehaviorwithintheyieldsurface,PortofAnchorage,Alaska,CavityExpansionCriticalStateModelforEvaluatingOCRinClaysfromPiezoconeTests,whereM=6sinf/(3-sinf)andL=1Cs/Cc0.8,Criticalstatesoilmechanics,Initialstate:e0,svo,andOCR=sp/svoSoilconstants:f,Cc,andCs(L=1-Cs/Cc)Usingeffectivestresses,CSSMaddresses:NCandOCbehaviorUndrainedvs.Drained(andotherpaths)Posit