3-D Inversion Of Incident Earthquake Motion And The Effects Of Soft Layer On Earthquake Ground Motion

Soil has filtering and amplification effect to earthquake ground motion, so it isdifferent from the actual situation that inputting the surface seismic record directly,and it’s need to input the ground seismic record for the major projects, therefore it hasimportant engineering significance to obtain bedrock ground motion inversion by thesurface ground motion records. At present, the inversion of1-D and2-D has beenstudied, the paper proposes a method for inversion of3-D incident earthquake groundmotion. Through the analysis of both linear and nonlinear soil, we can get theconclusion preliminary that the method of3-D inversion can be replaced by2-Dmethod.Soft layer area is a common site of coastal areas, and so much data shows thatthe soft soil has amplification effect on seismic response, so it has practicalsignificance for the study of the soft soil layer effect on seismic response. Based onfour kinds of soft soil field, it is able to calculate response spectrum in different layerthickness and different saturation layer,with tianjin, Taft wave, El centro wave as theincident wave, the influence law is obtained. Through the research and analysis, thepeak of response spectrum decreased with the increase of the thickness andembedment depth of soft soil, however soft soil have obvious amplification effect onresponse spectrum under a certain frequency. The characteristic site period increaseswith the increase of the thickness of the saturated soil and the embedment depth.