FREDLUND边坡稳定的未来

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1、WhatistheFutureforSlopeStabilityAnalysis?(AreWeApproachingtheLimitsofLimitEquilibriumAnalyses?)Dr.DelwynG.FredlundUniversityofSaskatchewan,CanadaSecondSymposiumandShortCourseonUnsaturatedSoilsandEnvironmentalGeotechnicsBudapest,HungaryNovember4-5,2003IntroductionLimitEquilibriummethodsof

2、sliceshavebeen“Good”forthegeotechnicalengineeringprofessionsincethemethodshaveproducedfinancialbenefitEngineersareoftensurprisedattheresultstheyareabletoobtainfromLimitEquilibriummethodsSoWhyChange?ThereareFundamentalLimitationswithLimitEquilibriumMethodsofSlices??TheboundariesforaFREEBO

3、DYDIAGRAMarenotknown-TheSHAPEfortheslipsurfacemustbeassumedTheLOCATIONofthecriticalslipsurfacemustbefoundbyTRIALandERRORSHAPEandLOCATIONarethedrivingforceforaparadigmshiftObjectivesofthisPresentation:ToshowthegradualchangethatisemerginginthewaythatslopestabilityanalysescanbeundertakenToi

4、llustratethebenefitsassociatedwithimprovedproceduresfortheassessmentofstressesinaslopeOutlineofPresentationProvideabriefSummaryofcommonLimitEquilibriummethodsalongwiththeirlimitations(2-D&3-D)TaketheFIRSTstepforwardthroughuseofanindependentstressanalysisTaketheSECONDstepforwardthroughuse

5、ofOptimizationTechniquesIsaLimitEquilibriumAnalysisanUpperBoundorLowerBoundSolution?LimitEquilibriumMethodsprimarilysatisfytherequirementsofanupperboundtypeofsolutionReason:theshapeofslipsurfaceisselectedbytheanalystandtherebyadisplacementboundaryconditionisimposedLimitEquilibriumandFini

6、teElementBasedMethodsofAnalysesWWWWWWWWNLimitEquilibriumMethodofAnalysisSm=tadldlsndlFiniteElementBasedMethodofAnalysisldtadlQUESTION:HowcantheNormalStressatthebaseofaslicebemostaccuratelycomputed?ConsidertheFreeBodyDiagramsusedtocalculatetheNormalStress?AssumptionforallLimitEquilibriumA

7、nalysisSoilsbehaveasMohr-Coulombmaterials(i.e.,friction,f',andcohesion,c')Factorofsafety,Fs,forthecohesivecomponentisequaltothefactorofsafetyforthefrictionalcomponentFactorofsafetyisthesameforallslices()[]msnsSFuFc=-+bfsb'tan'SummaryofAvailableEquationsAssociatedwithaLimi