Research On Near-fault Seismic Ground Motion Considering Soil Layer Amplification

Near-field earthquakes have a special effect on far-field earthquakes.The number of property losses and casualties in earthquakes are mostly concentrated in the near-field area.It is of great practical significance to analyze the ground motion under the action of near-field earthquakes.The existence of soil layer is a factor that aggravates the ground motion of near-field.In the study of ground motion of near-fault earthquakes,considering the existence of objective soil layer and studying the effect of soil layer on ground motion amplification,the near-fault earthquake considering soil layer amplification is considered.Ground motion research has important theoretical significance.The research contents and results are as follows:The application of the finite-fault source model in the numerical simulation of the ideal model ground motion is studied.The ABAQUS finite element analysis software is used to establish the free-field model without considering the soil layer and the model considering the surface sedimentary soil layer,and simulate the surface of the near-fault earthquake.The ground motion of the receiving points at different locations compares the data of the two sets of models to obtain the amplification effect of the soil layer on the ground motion.The results show that the peak ground acceleration(PGA)in the horizontal direction of the upper plate is larger than the PGA value in the horizontal direction of the lower plate when considering the soil layer and not considering the soil layer.Specifically,the PGA distribution at the receiving point of the upper disk is 0.4-1.8m·s-2;while the PGA of the receiving point of the lower disk is concentrated below 0.4 m·s-2,and the PGA value of only a few points exceeds 0.4.m·s-2.PGA at different spatial points of the upper and lower discs,peak ground velocity(PGV for short)and peak ground displacement(PGD for short)have obvious fluctuations with spatial position.Phenomenon;ideal model surface sedimentary soil layer has amplifying effect on ground motion.Specifically,the magnification of PGA is mainly concentrated between 1 and 3 times;the magnification of PGV is mainly concentrated between 1 and 2 times:The magnification of PGD is not particularly obvious but also has some amplification.The effect of different soil thickness on the ground motion of near-fault earthquakes is regular.The near-fault ground motion of the Weihe Basin caused by fault rupture in the Weihe Basin is studied.The actual surface sedimentary soil layers in the Weihe Basin are considered in the numerical simulation.The results show that the PGA value of the upper plate is larger than the PGA value of the lower plate,and the upper and lower disk effect appears.Specifically,the PGA distribution at the receiving point of the upper disk is between 0.1 and 1.5 m·s-2,while the PGA at the receiving point of the lower disk is distributed between 0.1 and 1.1 m·s-2.The PGA values at different spatial points of the upper and lower plates vary with the "fluctuation" phenomenon;the surface sedimentary soil layers of the Weihe Basin have a great influence on the ground motion of the Weihe Basin.The magnification of the PGA is mainly concentrated at 1?2 times.There is also a certain amplification effect between PGV and PGD.