强地震作用引起的近断层地表破裂分

强断层断层ANAPPROACHTOEVALUATEGROUNDSURFACERUPTURECAUSEDBYREVERSALFAULTMOVEMENT赵纪1,21,3师静11.国学(InstituteofEngineeringMechanics,ChinaEarthquakeAdministration)2.国学国冻点试验(StateKeyLaboratoryofFrozenSoilEngineering,CAREERI,CAS)3.尔滨业学学(SchoolofcivilEngineering,HarbinInstituteofTechnology)2006.3CONTENT•OVERVIEW•METHODOLOGY•ONSETOFSTRAINLOCALIZATION•EVOLUTIONOFSLIPPAGELINE•CONSTITUTIVEMODEL•INPUTOFTHEPROBLEM•EXAMPLESANDDISCUSSIONS•SOMEPROBLEMS1.OVERVIEW•PhenomenaofSurfaceRupture--Mostsurfaceruptureisconfinedtoarelativelynarrowzoneafewfeettoafewtensoffeetwide.--insomecasesprimarysurfacerupturealongbranchfaultscanbedistributedacrosszoneshundredsoffeetwideormanifestedasbroadwarps•CasualtyandEconomicalDamageTheCountermeasure•reinforcestructure?--takemeasurestoaccommodatewarpinganddistributivedeformation•Awayformwheresurfacerupturemaytakeplace--definesetbackdistancesEstimationofScaleofSurface•RuptureEmpiricalformulaebasedonearthquakeinvestigation;•NumericalmethodbasedonMechanicsStrongFormofAnalysisModelWeakFormofAnalysisModelKeyPoints•SomeConcepts•DetectOnsetConditionoftheRupture•EvolutionPropertiesoftheRupture•ConstitutiveEquationofStressedSoils•NumericalMethodStabilityorFailureofMaterialsStationarywave,FlutterPositivenessofthesecondorderpowerofmaterials,theuniquenessofsolutionofgoverningequations,thebifurcationvariationalprinciples.Bifurcation,Weakdiscontinuity---strainStrongdiscontinuity---displacementUnstableFailureOnsetandEvolutionoftheRuptureConstitutiveEquation(Intact)ConstitutiveEquation(Interface)NumericalMethods•LEMLocalEnrichmentMethods•Multigrid-likeprocedures•Generalizedmathematicalhomogenizationtheory•Multiscaleenrichmentbasedonpartitionofunitymethod•Meshfree•XFEM+PU•XFEM+LevelSetTwostepsandOnestep•Onsetoftheslipline•Evolutionoftheline•Onset+Evolutionoftheline2.METHODOLOGY•Elasto-plasticsoilbodyunderdislocation•Chickwhen&wheretheonsetofstrainlocalizationwilloccur•Andwhen&whereslippagelinewillformed•HowslippagelinewillextendConstitutivemodel(frictionlaw)PlasticConsistencycondition•DiscontinuousDisplacementExtendFiniteElementMethodwithquasi-staticelastoplasticityFigure1AnalysisdomainFigure2Flowchartofruptureanalysis3.ONSETOFSTRAINLOCALIZATION•Hill’sDefinition,Where,AiscalledAcousticTensor,misslippagevector,andnisnormalvectorofslippageline.m,ncanbegottenfromtheoreticalanalysisornumericalcalculationasnCnAep⋅⋅=0=⋅mA10.80.60.40.200.20.40.60.8105.1041.1051.5.105ffl()lFigure.3Determinantvalueofacoustictensorwithxαcos4.EVOLUTIONOFSLIPPAGELINE•AssumedmandnareknownSlipratewillberelatedtoconstitutivemodelofafterslippagelineformed)(::)(::~nmsymCusymC⊗∂∂∇∂∂ℑ=σσχζδΘΘ&&5.CONSTITUTIVEMODELONTHEBAND•Yieldingfunction•Potentialfunctionitspreciseformisnotnecessarysince[]0tan:)(:)(=⊗−Χ−⊗=Θgsnnlnϕσσsnm)(⊗∝∂Ξ∂σ6.INPUTOFTHEPROBLEM•Dynamic---ÆQuasi-static•Assumed1.Contributiontosurfacerupturebyvibrationinsoilbodyisthatsoilproperties,strength,stiffnessetc.willvarywiththenumberofwavecrestonaccelerationtimehistory.•Assumed2.Vibrationdisplacementanddislocationtimehistoryonthebedrocktakeasinputofquasi-staticproblem.Figure4Accelaration,displacementanddynamic+staticdislocationtimehistory7.EXAMPLESANDDISCUSSIONS•Propertiesorparametersofsoil•VerifiedDrucker-PregerYieldingFunction1IπFigure6Meridiansandcurveonhydraulicplane•Thicknessofsoillayer100metersFigure7DeformationsdistributiononZ=0~90mofsoilunderdislocationofbedrock•Thicknessofsoillayer30metersFigure8DeformationsdistributiononZ=0~90mofsoilunderdislocationofbedrockFigure9Slippagelineandextensivedeformation8.Conclusion•Thismethodtakesintosomeimportantfactors,andhascapabilitytosimulatethefailurephenomenainsoil.Twoexamplesilluminatethepoint,indespiteofverysimpleconstitutivemodelsareimposed.•Whenthicknessofsoillayermorethan100meters,thereislittlepossibilitygroundsurfaceruptureoccur;andwhenthicknessofsoillayer30meters,thereishighpossibilitygroundsurfaceruptureorscarpoccur.•Themethodhasprovidedabasetofurtherstudyongroundsurfaceruptureandotherengineering.9.ProblemsneedtobeNoted•Howtoregularizetheinput(dislocation-timehistory)oftheproblem(magnitude,recording,dateprocessingandsoon)•Loadinginterfacelocation•Brittleorductilefailureofgeomaterialsunderdynamicloading;parameterscalibrationofConstitutiveequation•Stressfieldcausedbygravityandtectonization•Programming•conciseandcoarseway,easytouseorburdensomeandelaboration,hardtodealwith?Thanksand????