地下空洞的面波场地效应数值模拟研究

Numerical Simulation of Site Effect of Surface Wave in Underground Cavities

摘要:

工程中存在大量的地下空洞结构，这些空洞会影响地震波的传播从而产生场地效应。通过数值模拟方法研究分析地下空洞对面波传播的影响和场地效应。结果表明：面波在传播中遇到地下空洞会发生散射和反射，产生反方向传播的反射面波和向空间传播的转换体波，使得空洞的远源侧中部和下方能量大幅增强，远源侧地表及近地表处能量有所减弱，近源侧能量稍有增强。空洞的场地效应一般随空洞埋深的增加而减小，随空洞直径的增加而增加，总体来说地震动水平分量的场地效应比垂直分量更大。

Abstract:

There are a large number of underground cavities in the geotechnical engineering projects. These cavities will affect the propagation of seismic waves and thus arise site effects. In this paper, the numerical simulation method was used to analyze the effect of an underground cavity on surface wave propagation and site effect. The surface wave will be scattered and reflected when it encounters the underground cavity in the process of propagation, resulting in reflected surface wave propagating in the opposite direction and converted body wave propagating in the space. Then the energy in the middle and low part of far source side of the cavity will be greatly increased, on the surface and near the surface of far source side will be decreased, and the energy in the near source side will be slightly increased. The site effect of the cavity is generally decreased with the increase in cavity depth, and increased with the increase in cavity diameter. Generally speaking, the site effect of the horizontal component of ground motion is larger than that of the vertical component.