99[USACE] Geotechnical Analysis by the Finite Elem

DEPARTMENTOFTHEARMYU.S.ArmyCorpsofEngineersCECW-EGWashington,DC20314-1000ETL1110-2-544TechnicalLetterNo.1110-2-54431July1995EngineeringandDesignGEOTECHNICALANALYSISBYTHEFINITEELEMENTMETHODDistributionRestrictionStatementApprovedforpublicrelease;distributionisunlimited.DEPARTMENTOFTHEARMYETL1110-2-544U.S.ArmyCorpsofEngineersCECW-EGWashington,DC20314-1000TechnicalLetter31July1995No.1110-2-544EngineeringandDesignGEOTECHNICALANALYSISBYTHEFINITEELEMENTMETHOD1.PurposeThisengineertechnicalletter(ETL)providesguid-complexgeometries,avarietyofloadingconditions,anceontheuseofthefiniteelementmethodinthenonlinearmaterialbehavior,nonhomogeneousmate-analysisofproblemsingeotechnicalengineering.rialdistribution,andsoil-structureinteractioneffectsThisETLisintendedforengineerswhoareunfa-thatarenotaccountedforinthesimplerprocedures.miliarwiththemethod,butwhoareinterestedinUnfortunately,theFEMisanunderutilizedtechnol-understandingitspotentialuseingeotechnicalogyinthedesignprocessbecauseengineersbelieveengineering.itsapplicationistimeconsuming,expensive,and2.ApplicabilityThisETLappliestoallHQUSACEelementsandUSACEcommandshavingresponsibilitiesforthedesignofcivilworksprojects.3.ReferencesSeeAppendixA.cation,andwhatresourcesintermsoftime,effort,4.Backgrounda.Numericaltechnique.Thefiniteelementseepageanalysis.AppendixAincludesdiscussionsmethod(FEM)isanumericaltechniquewhichcanonthedetailsoffiniteelementmodeling,casehisto-beusedtosolveproblemsingeotechnicalengineer-ries,andasectionwhichwillhelpinterestedengi-ing.ComputercodesbasedontheFEMhavebeenneersfindfurtherinformationonhowtheFEMcandevelopedtosolveproblemsinvolvingsoilstructurehelpintheanalysisoftheirproblems.interaction,embankmentconstruction,seepage,andsoildynamics.b.Traditionalmethodsofanalysis.Traditionalmethodsofanalysisoftentimesusetechniquesthatarebasedonassumptionsthatoversimplifytheprob-lemathand.Thesemethodslacktheabilitytoac-countforallofthefactorsandvariablesthede-signengineerfacesandmayseverelylimittheaccuracyofthesolution.Thefiniteelementmethodcanovercomemanyoftheseshortcomings,therebyofferingmanyadvantagesovertheconventionalapproaches.Accordingly,theFEMaccountsforcomplicated.However,withrecentadvancesinthehardwareandsoftwareassociatedwithmoderndigi-talcomputers,aproperlyconductedFEManalysiscanbeconductedrapidlyandatarelativelylowcost.5.ObjectiveTheobjectiveofthisETListoprovideabasisforunderstandingwhatcanbelearnedfromfiniteele-mentanalyses,whatskillsarerequiredforitsappli-andcostareinvolved.Theemphasisisonpracticalapplicationsofthemethod.AppendixAcontainsinformationastohowtheFEMcanbeusedinsoil-structureinteraction,embankmentconstruction,andFORTHEDIRECTOROFCIVILWORKSiDEPARTMENTOFTHEARMYETL1110-2-544U.S.ArmyCorpsofEngineersCECW-EGWashington,DC20314-1000TechnicalLetter31July1995No.1110-2-544EngineeringandDesignGEOTECHNICALANALYSISBYTHEFINITEELEMENTMETHODTableofContentsSubjectParagraphPageSubjectParagraphPageAppendixACaseHistory:Sheet-pileWallGeotechnicalAnalysisbytheFiniteElementMethodChapter1IntroductionBackground.........................1-1A-1TypesofProblems....................1-2A-1WhatCanbeLearnedfromFiniteElementAnalyses.................1-3A-1InformationRequiredforFiniteElementAnalyses.................1-4A-2SkillsRequiredforGeotechnicalFiniteElementAnalyses............1-5A-3RequiredEffortandCost...............1-6A-3FiniteElementCodesUsedonCorps'Projects....................1-7A-3Chapter2StaticSoilStructureInteractionProblemsResultsandUseofSSIAnalysis.........2-1A-4ImportantFeaturesofSSIAnlaysis.......2-2A-4MaterialBehaviorModels..............2-3A-4Stress-StrainMaterialPropertyValues..........................2-4A-5FiniteElementMesh..................2-5A-5ConstructionSequence................2-6A-6CalibrationoftheEntireModel.........2-7A-6CaseHistory:RetainingWallatBonnevilleNavigationLocks...........................2-8A-6Analysis.........................2-9A-10Chapter3EmbankmentConstructionProblemsResultsandUseofEmbankmentConstructionAnalysis..............3-1A-15ImportantFeaturesofEmbankmentConstructionAnalysis..............3-2A-15CaseHistory:BirchDam..............3-3A-17CaseHistory:NewMelonesDam.......3-4A-18Chapter4SeepageProblemsResultsandUsesofSeepageAnalyses.........................4-1A-26TypesofSeepageAnalyses............4-2A-26ConstitutiveLawandMaterialProperties........................4-3A-26CaseHistory:S.A.MurrayHydroelectricPlant................4-4A-27CaseHistory:CerrillosDam...........4-5A-28Chapter5SourcesforFurtherInformationFiniteElementCodesUsedintheAnalysisofPastCorpsofEngineersGeotechnicalProjects......5-1A-35References.........................5-2A-35ETL1110-2-54431Jul95A-1APPENDIXA:GEOTECHNICALANALYSISBYTHEFINITEELEMENTMETHODChapter1Introduction1-1.Backgrounda.Purpose.Thepurposeofthisengineeringtechnicalletter(ETL)istoprovideguidancetoengi-neerswhoareunfamiliarwiththefiniteelementmethod,butwhoareinterestedinunderstandingitspotentialforuseingeotechnicalengineering.Theemphasisisonpracticalapplications.Theobjectiveistoprovideabasisforunderstandingwhat