重复反射理论在计算地表面地震波时的应用

The Application of Repeated Reflection Theory on calculating Seismic wave on the ground

以某沉淀池设计地震波的计算为例,根据重复反射理论提出一种由典型地震波和土层波阻抗计算场地设计地震波的方法,并证明该计算方法的必要性和可行性.场地覆盖土层假定为无限延伸的水平成层土,基岩面及以下按照线性半无限空间各向同性考虑,基岩面为全反射界面,采用Arkquake软件将初选地震波输入地层,运用等效线性化方法考虑土体非线性,并用傅里叶变换进行频域计算.考虑到各处场地覆盖土层的差异,选用多点分别计算基岩波和地表面地震波.这种方法计算出的地表面地震波能较好地考虑局部场地效应,一定程度上减小地震烈度异常现象,为今后实际工程中地震波的选取提供一种较为实用的参考方法.

Based on the repeated reflection theory,a method of inversing seismic wave on the ground is suggested in this paper.This calculation is hased the typical seismic wave and soil wave impedance.The paper took the rectangle pool for example to calculate the input seismic waves,assumed that the site soil was horizontal layer and extended infinitely,the bedrock was linear semi-infinite space and isotropic,and the surface reflected totally.In the program Arkquake,the two typical seismic waves were put into the layer,On the basis of one-dimensional wave theory and the properties of soil,applying equivalent linearization for nonlinear model of the soil,the program has calculated the waves on the bedrock,In the same way.The corresponding waves on the ground was exported.During this process,the Fourier transform was used in analysing the frequency.In conclusion,the paper compares the amplitude of initial seismic waves and the output ones and draw a conclusion that the count is necessary.Through the comparative analysis of the frequency spectrums,it proves the practicability of this method.Considering differences between the site soil,multiple spots were adopted to calculate waves separately on the bedrock and the ground,this method takes local site effects into account and reduces the phenomenon of abnormal intensity to some degrees,and provided a practical approach for selecting seismic wave for reference.