倾斜入射地震波作用下成层场地动力反应的界面子波算法

Interfacial wavelet algorithm for dynamic response of horizontal layered site due to inclined seismic waves

为提高成层半空间自由波场的一维化时域方法的计算效率和精度,分析了SH波在层状介质中的传播方式、旅行时间和反射系数等问题,基于惠更斯–菲涅耳波动观点,将波阻抗界面看作次级子波源(简称为界面子波),提出了倾斜入射地震波作用下成层场地动力反应的界面子波算法,并通过模型试算验证了此方法的正确性。与常规数值法相比,此方法无需划分网络单元,也无需处理人工边界条件,从而极大地减少了计算工作量和节点之间的传递误差,具有速度快、精度高、稳定性好等特点,是一种计算成层场地动力反应的实用方法。

Some properties of SH waves in layered media are analyzed such as propagating path, reflecting cofficent and travelling time in order to improve the accuracy and efficiency of 1-D finite element method dealing with seismic response problem of horizontal layered site for inclined SH waves in time domain. Based on the Huygens wave principle, impedance interfaces are regarded as the secondary sources or wavelet sources, which are called interfacial wavelets. The relation between interfacial wavelets can be expressed as a group of time delay equations, and the motion of interfaces can be obtained by solving the time delay equations. The earthquake motion can be ascertained from surface wavelets. The new method is called an interfacial wavelet algorithm and demonstrated by two corresponding numerical models. When using this method, mesh divisions and artificial boundary conditions need no treatment so that computing amount and transmission errors between nodes are reduced greatly. It is very fit to solve seismic response in layered media.