SH波在浅埋椭圆孔上的散射对地震动的影响

Effect of scattering on the ground motion above a subsurface elliptic cavity by incident SH-waves

用复变函数方法研究了浅埋椭圆柱形孔洞对任意角度入射的平面SH波的散射及其对地震动的影响.利用SH波的对称性构造了1个能够自动满足水平表面上应力自由边界条件的散射波函数,将半空间中的问题转化为求解1个全空间中椭圆形孔洞的散射问题,最终将问题归结为对一组无穷代数方程组的求解,给出了浅埋椭圆孔洞附近地面运动的数值结果.研究表明浅埋孔洞与水平表面存在强烈的相互作用,地震动将受到很大影响,在地面建筑物抗震设计时应对“隐蔽地形”的存在予以充分重视.

The scattering of SH-wave with arbitrary incident angle by a subsurface elliptic cavity in half space is studied together with its influence on ground motion. The complex function method is used here. Firstly, construct a scattering wave function satisfying zero-stress condition on horizontal surface by using the symmetry of SH-wave, then transform the problem in half space into the scattering of SH-wave to an elliptic cavity in whole space, finally acquire the solution by solving a series of algebraic equations. Numerical results of the ground motion on subsurface elliptic cavity are provided. The research indicates that great interaction exists between the subsurface cavity and the horizontal surface, which will bring on great influence on ground motion. Therefore enough importance must be attached to the existing of subsurface cavity while finishing seismic design.