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3DEC数值模拟方法2013武汉依泰斯卡(武汉）咨询有限公司提纲3DEC(5.0)软件特点3DEC(5.0)理论基础3DEC(5.0)新功能3DEC(5.0)算例分析提纲3DEC(5.0)软件特点3DEC(5.0)理论基础3DEC(5.0)新功能3DEC(5.0)算例分析Whatis3DEC?•ADistinctElementcodethatallowsthesimulationoftheinteractionofblocks–e.g.jointedrockmass,masonrywallWhatis3DEC?•Discontinuitiesareregardedasdistinctboundaryinteractionsbetweenblocks•Contactsareautomaticallyupdatedascalculationprogresses–largedisplacementsareallowed•Non-linearforcedisplacementbehaviormaybeassignedtocontacts(joints)Whatis3DEC?•3DECblocksarerigidordeformable•Deformableblocksareautomaticallymeshedwithtetrahedratosimulateanon-linearcontinuumWhatis3DEC?•Solvesthefulldynamicequationsofmotionevenforquasi-staticproblems•Allowsforlargedisplacements,rotationsanddynamicanalysesNSWithoutGroundSupportWithGroundSupportDisplacementMagnitudeNSNSWithoutGroundSupportWithGroundSupportDisplacementMagnitudeNSWhatis3DEC?•3DECisbestsuitedtomodelingdiscontinuousmaterials(containingmanyintersectingdiscontinuitiesin3D)thatexhibitnonlinearbehavior矿层分布模型地质构造分布开挖后对地表建筑物的影响屈服矿柱分布情况矿山开采稳定性分析研究当前开采条件下矿柱几乎没有屈服断层影响不大矿藏分布三维模型拉底步骤矿岩三维节理模型拉底后矿岩出露模型矿岩崩落数值模拟对崩落速度和规模进行预测崩落过程模拟NuclearWasteDisposalShotcreteConcreteCanistercoverLocalizationinclaystoneat6monthsClaystoneReproducedwithpermissionofANDRAHydraulicFractureDiscreteFractureNetworkFracturedreservoirmodelHydraulicFractureFluidpressureinjointsduringinjectionTopportionofreservoirhiddenforeaseofviewingMicroseismicityFracturedrockvolumeloadedaxiallywith10MPaconfiningstressFundamentalRockMechanicsSimulatedunconfinedcompressiontestoncrystallinerocksampleDisplacementsGrainstructureExaggerateddeformationSlopeStability•AutomaticFactorofSafetycalculationfor3Dslopes•UsesShearStrengthReductionmethodAbutmentstabilityassessmentatHongricharchdam11Kolijietal,2001.Int.J.Hydropower&Dams,18,56-61TopplingNormalfaultingintheupperpartoftheslopeS-shapeddeformationofrocklamellaeFlexuraltopplingNormalfaultingS-shapeddeformedrocklamellae提纲3DEC(5.0)软件特点3DEC(5.0)理论基础3DEC(5.0)新功能3DEC(5.0)算例分析离散元方法离散元的理论基础是牛顿第二定律。离散元法是将所研究的区域划分成一个个分立的多边形块体单元，单元与单元之间具有一定的初始接触状态，随着单元的平移和转动，调整各个单元之间的接触关系。最终，块体单元可能达到平衡状态,也可能一直运动下去。因此，离散元法适用于研究节理系统或块体集合在准静力或动力条件下的运动问题。离散元法以各种块体为研究对象，块体与块体之间没有变形协调的约束，只需要满足力的平衡条件。构成单元的节点可以分离。单元之间的相互作用力可以根据力和位移的关系求出，而单个单元的运动则完全根据该单元所受的不平衡力和不平衡力矩的大小按牛顿运动定律确定。TypesofDiscreteElementMethodsforDiscontinuumAnalysis•DistinctElementUseexplicittime-marchingschemetosolveequationsofmotiondirectly.Bodiesmayberigidordeformable,contactsaredeformable•ModalMethodsSimilartodistinctelementmethodinthecaseofrigidblocks.Fordeformablebodies,modalsuperpositionisusedsonon-linearityisdifficulttoimplement•DiscontinuousDeformationAnalysisAssumescontactsarerigidbodiesandbodiesmayberigidordeformable.No-penetrationisachievedbyiteration•MomentumExchangeMethodsAssumeboththecontactsandbodiestoberigid.Momentumisexchangedbetweentwocontactingbodiesduringcollision.Canrepresentfrictionsliding.DEMDefinitionsThename“DiscreteElementMethod”(DEM)shouldbeappliedtoamethodonlyifit*:1.allowsfinitedisplacementsandrotationsofdiscretebodies;includingcompletedetachment2.recognizesnewinteractions(contact)automaticallyasthecalculationprogressesAdiscreteelementcodewillembodyanefficientalgorithmfordetectingandclassifyingcontacts.Itwillmaintainadatastructureandmemoryallocationschemethatcanhandlemanyhundredsorthousandsofdiscontinuitiesorcontacts.Thename“DistinctElementMethod”isusedforaDEMthatusesanexplicitdynamicsolutiontoNewton’slawsofmotion.*Cundall,P.A.,andR.D.Hart.”NumericalModelingofDiscontinua,”EngineeringComputations,9(2),101-113(1992)Finiteelementcodesformodeling“discontinua”areoftenmodifiedcontinuumprograms,whichcannothandlegeneralinteractiongeometry(e.g.manyintersectingjoints).Theirefficiencymaydegeneratedrasticallywhenconnectionsarebrokenrepeatedly.DistinctElementMethodThreeaspects...1.Geometry2.Contactmechanics3.SolidbodymechanicsDistinctElementMethodGeometry1)Specificationofshapesin2and3dimensions2)Interactionofpairsofcontactingblocksorparticles3)Identificationofcontactcharacterbetween2blocksDistinctElementMethodSpecificationofshapesin2and3dimensions•2&3dimensions–PFCdisks&spheres•2dimensions–UDECarbitrarypolygons–convexandconcave–withroundedcorners•3dimensions–3DECarbitrarypolyhedra–concavebodiesareconstructedofseveralconvexbodiesattachedtogetherDistinctElementMethodInteractionofpairsofcontactingblocksorparticlesIfweattempttoidentifyneighboringblocksbyanexhaustivescan(i.e.eachblocktestedagainsteachother),thenthesearch-timeisproportionaltoN2whereNisthenumberofblocks.Twomethodstoreducesearchtime:1)Cell-mapping,usedinUDEC&3DEC2)Circulatingdatastructure,thatmimicsthetopologyofthesystemasusedinUDECCell-mappingThesolution-spaceiscoveredbyrectangularcells.Eachblockdepositsamarkerinallthecellsthatitoverlaps–thisprocesstakesNproportionaltime.Eachblockcanfindallofitsneighborsbylookinginjustthosecellsthatitoverlaps-thisprocessisalsoNproportional,ifthecellsizeisofasimilarordertotheblocksize12345678910111213141516171819202122232425ACBBlockenvelopeA,B,C=blocks00000000000000000AAB0C0C0B0AA0C0C0C0CCellentriesinm