The Effects Of The Fault Dip On The Characteristics Of The Near-fault Ground Motion

In recent years,because of the great damages caused by several destructiveearthquakes occuring lately,as well as of the accumulation of the near-faultseismic records ,the research of characteristics of near-fault ground motion hasbecome a hot focus of earthquake engineering at home and abroad.In the last fewyears,reseachers usually used the method of statistical analysising the attenuationrealation of near-fault seismic records to study the characteristics of near-faultground motion.However,this method strongly depends on the quantity and qualityof the seimic records.As a matter of fact, seismic records is still insufficient so far,in addition to the various influencing facors of the near-fault ground motion,however, with respect to each facor,the amount of the records becomes less andless.As the result,more and more reseachers attempted to use the method of theexplicit finite-element numeric simulation to study the near-fault groundmotion ,and they have achieved many valuable results.In this paper,the authoruses the method of the explicit finite-element numerical simulation, which isbased on the most simple two-dimensional-finite-element modle and kinematicsource model,to study the basic characteristics of near-fault ground motion, suchas the changing tendency of the hanging-wall effect and the vertical effect as weonly change the fault dip or the depth of the top of the fault. More details aresummarized as follows:1)The research methods of the near-fault ground motion are systemicallyreviewed and compared.The basic characteristics of near-fault ground motion aresummarized ,such as the hanging wall effect, the vertical effect,the rupturedirectivity effect,the fling step effect and so on.2)The computing methods used in the numerical simulation for wavemotion—the lumped-mass finite element method and the artifical boundarycondition,are introduced in detail.And the computing programes for solving thedynamic response of both SH and P-SV problem based on point source model arecoded individually.3)In this paper,the author analyses and compares both the dynamic andthe kinematic source model simply. The kinematic source model based on theassumption of the finite fault is introduced at length. To make up for the lack ofthe high-frequency components in the slip time function ,an effective measure istaken in this paper. In addition,the computing programes for solving the dynamicresponse of both SH and P-SV problem(corresponding to the strike-slip fault andthe thrust fault separately) based on line source model are coded individually4)As far as the the strike-slip fault and the thrust fault,we only change thefault dip but keeping the other influencing parameters all the same to study thechanging tendency of the hanging-wall effect and the vertical effect. Similarly,aswe only change the depth of the top of the fault but keeping the other influencingparameters all the same,We get the changing tengdency of the vertical effect,aswell as the peak values of the ground motion.At last,the research work are generalized and the problems which needfurther to be studied in the future are discussed.