简介:Adetailthree-dimensionalPwavevelocitystructureofBeijing,TianjinandTangshanarea(BTTarea)wasdeterminedbyinvertinglocalearthquakedata.Intotal16048Pwavefirstarrivaltimesfrom16048shallowandmid-depthcrustalearthquakes,whichoccurredinandaroundtheBTTareafrom1992to1999wereused.ThefirstarrivaltimesarerecordedbyNorthernChinaUnitedTelemetrySeismicNetworkandYanqing-HuailaiDigitalSeismicNetwork.Hypocentralparametersof1132earthquakeswithmagnitudeML=1.7~6.2andthethree-dimensionalPwavevelocitystructurewereobtainedsimultaneously.TheinversionresultrevealsthecomplicatedlateralheterogeneityofPwavevelocitystructurearoundBTTarea.Thetomographicimagesobtainedarealsofoundtoexplainotherseismologicalobservationswell.
简介:3-DS-waveQstructureinJiashiearthquakeregionisinvertedbasedontheattenuationofseismicwavesrecordedfromearthquakesinthisregionin1998bytheResearchCenterofExplorationGeophysics(RCEG),CSB,andaroughconfigurationofdeepcrustalfaultsintheearthquakeregionispresented.First,amplitudespectraofS-wavesareextractedfrom450carefully-chosenearthquakerecords,calledobservedamplitudespectra.Then,afterinstru-mentalandsiteeffectcorrection,theoreticalamplitudespectraaremadetofitobservedamplitudespectrawithnonlineardampedleast-squaresmethodtogettheobservedtraveltimeoverQ,providedthatearthquakesourcesconformtoBrune¢sdiskdislocationmodel.Finally,by3-Draytracingmethod,theoreticaltraveltimeoverQismadetofitobservedtraveltimeoverQwithnonlineardampedleast-squaresmethod.Inthecourseoffitting,thevelocitymodel,whichisobtainedby3-Dtraveltimetomography,remainsunchanged,whileonlyQmodelismodified.Whenfittingcametothegivenaccuracy,theultimateQmodelisobtained.TheresultshowsthatanNE-trendinglowQzoneexistsatthedepthsof10~18km,andanNW-trendinglowQzoneexistsatthedepthsof12~18km.TheseroughlycoincidewiththeNE-trendingandtheNW-trendinglowvelocityzonesrevealedbyotherscientists.ThedifferenceisthatthelowQzoneshaveawiderrangethanthelowvelocityzones.
简介:Three dimensional velocity structure beneath the Kunming Telemetered Seismic Network(王椿镛)(王溪莉)(颜其中)Threedimensionalvelocityst...
简介:IntroductionTherearemanynumericalmodelingstudiesoftopographyforMTfieldsappearedinthepastliterature,butmostoftheworksare2-Dres...
简介:Basedontheseismicresponsecharacteristicsofspaceframestructures,anewtypeofseismicisolationbearingdefinedasathree-dimensionalseismicisolationbearing(3DSIB)isdevelopedinthispaper.Thebearingoffersexcellentpropertiessuchasmulti-dimensionalseismicisolation,reasonablerotationcapability,goodabilitytoresistliftingload,uncoupledstiffnessinhorizontalandverticaldirections,etc.Inthe3DSIB,thehorizontaldimensionisdesignedbycombiningtheTeflonslidingdeviceandhelicalspring,whiletheverticaldimensionisdevelopedbyintroducingdiskspringsorhelicalsprings.Themathematicalmodelofthe3DSIBwasestablishedanditsperformancewiththecriticalparameterswastestedonashakingtable.Furthermore,the3DSIBwasappliedina120mspanhangarstructureandsimulatedusingSAP2000softwaretoevaluateitsperformanceinpracticalstructures.Theperformanceofthestructureswithandwithout3DSIBwascompared.Itisshownthatthehangarstructurewith3Dbearingsachievesabetterperformance.Theaxialforceandaccelerationresponseofthestructureswith3DSIBareeffectivelyreduced,whilethedisplacementresponseofthebearingiswithinthepredeterminedrange.
简介:Inthisstudytheseismicpoundingresponseofadjacentmulti-degree-of-freedom(MDOF)buildingswithbilinearinter-storyresistancecharacteristicsisinvestigatedthroughdimensionalanalysis.Theapplicationofdimensionalanalysisleadstoacondensedpresentationoftheresponse,andtheremarkableself-similaritypropertyforbilinearMDOFbuildingswithinelasticcollisionisuncovered.Itisshownthatwhentheresponseisexpressedintheappropriatedimensionlessform,responsespectraforanyintensityoftheexcitationcollapsetoasinglemastercurve.ThereducedΠsetexplicitlydescribestheinteractionbetweenthecollidingstructures.TheeffectofpoundingontheMDOFbuilding’sresponseisillustratedusingthreewell-dividedspectralregions(amplified,de-amplifiedandunaffectedregions).Parametricstudiesareconductedtoinvestigatetheeffectsofthestorystiffnessofstructures,thestorystiffnessratioandmassratioofadjacentbuildings,thestructuralinelasticcharacteristicsandthegapsizevalues.Resultsshowthat(i)theinfluenceofsystemstiffnessratiotothelighterandmoreflexiblebuildingismoresignificantinthefirstspectralregion,wherethemaximumresponseofthebuildingisamplifiedbecauseofpounding;and(ii)thevelocityandpoundingforceoftheheavierandstifferbuildingisunexpectedlysensitivetothemassratioofadjacentbuildings.
简介:Smoothedparticlehydrodynamics(SPH)isamesh-freeadaptiveLagrangianparticlemethodwithattractivefeaturesfordealingwiththefreesurfaceflow.ThispaperappliestheSPHmethodtosimulatethelarge-amplitudelateralsloshingbothwithandwithoutafloatingbody,andtheverticalparametrically-excitedsloshinginatwo-dimensionaltank.ThenumericalresultsshowthattheSPHapproachhasanobviousadvantageoverconventionalmesh-basedmethodsinhandlingnonlinearsloshingproblemssuchasviolentfluid-solidinteraction,andflowseparationandwave-breakingonthefreefluidsurface.TheSPHmethodprovidesanewalternativeandaneffectivewaytosolvethesespecialstrongnonlinearsloshingproblems.
简介:Usingthreedimensional(3D)viscoelasticfiniteelementmethod(FEM)westudythedynamicevolutionpatternofthecoseismicchangeofCoulombfailurestressandpostseismicchange,ontimescaleofhundredsyears,ofrheologicaleffectinducedbytheMS=7.2XingtaiearthquakeonMarch22,1966.Then,wesimulatethecoseismicdisturbanceinstressfieldinNorthChinaanddynamicchangerateonone-yearscalecausedbytheXingtaiearth-quakeandTangshanearthquakeduring15yearsfrom1966to1980.Finally,wediscussthetriggeringofastrongearthquaketoanotherfuturestrongearthquake.
简介:Athree-dimensionalcrustaldensitymodelbeneathNorthChinaisdeterminedusingP-wavetraveltimesandgravitydatumbysequentialinversionmethodinthispaper.Toimprovetheuniquenessofthesolution,weusedalinearrelationshipbetweenvelocityanddensitytoachievemutualconversionsandconstraintsbetweenvelocitydifferenceanddensitydifference.Algebraicreconstructiontechnique(ART)wasusedindensityinversion,whichhighlyimprovedthecalculationspeedcomparingwithcommonleastsquaresmethod.TheinversionresultsindicatethatthecrustaldensitybeneathNorthChinaisextremelyinhomogeneouswithitsdistributioncoherentwithregionaltectonics.ThelowercrustofTaihangmountaintectoniczoneshowsanobviouslowdensitycharacteristic.Weproposedthatitmaybeanindicatorofupwellingofmantlematerialsorpartialmeltingoflowermostcrust.
简介:Wepresentaparallelhybridalgorithmbasedonpseudospectralmethod(PSM)andfinitedifferencemethod(FDM)fortwo-dimensional(2-D)globalSHwavefieldsimulation.Thewhole-EarthmodelistakenasacrosssectionofsphericalEarth,andcorrespondingwaveequationsaredefinedin2-Dcylindricalcoordinates.SpatialderivativesinthewaveequationsareapproximatedwithefficientandhighaccuracyPSMinthelateralandhigh-orderFDMintheradialdirectiononstaggeredgrids.Thisalgorithmallowsustodividethewhole-Earthintosub-domainsinradialdirectionandimplementefficientparallelcomputingonPCcluster,whileretainshighaccuracyandefficiencyofPSMinlateraldirection.Atransformationofmomenttensorbetween3-DsphericalEarthandour2-Dmodelwasproposedtogivecorrespondingmomenttensorcomponentsusedin2-Dmodeling.Comparisonofmodelingresultswiththoseobtainedbydirectsolutionmethodshowsverygoodaccuracyofouralgorithm.Wealsodemonstrateitsfeasibilitywithalateralheterogeneouswhole-Earthmodelwithlocalizedvelocityperturbation.
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简介:象lumped参数模型那样的分离模型和有限元素模型广泛地在地震的土壤扩大的解决方案被使用。然而,任何一个模型都精确地不估计土壤沉积物的自然频率,也不模仿一抑制频率独立。这研究基于模式等价方法为分层的土壤沉积物的一个维的粘弹性的反应分析开发一个新分离模型。新分离模型是一系列集中的群众,弹簧和缓冲筒与一种特殊配置描绘的一个一个维的相等的multi-degree-of-freedom(MDOF)系统。相等的MDOF系统的动态反应是导出的经分解,物理参数以形式的性质被提出。相等的MDOF系统与可得到的理论解决方案通过扩大函数的比较被验证。在相等的MDOF系统的自由(DOF)的度的适当数字被估计。有存在的相等的MDOF系统的比较研究分离模型被执行。建议相等的MDOF系统罐头确切介绍土壤存款抑制的自然频率和hysteretic并且向更精确的结果提供更少DOF,这被显示出。