浅埋的圆柱形孔洞对SH波的散射与地震动

Scattering of SH-waves by a shallow buried cy lindrical cavity and the ground motion

研究了浅埋的圆柱形孔洞对以任意方向入射的平面SH波的散射与地震动问题。利用复变函数和多极坐标方法构造了问题的位移解。当入射波的波长与圆孔的半径相比较小时,地震动将受到较大的影响。影响地震动有三个主要参数:(1)SH波的入射角α0;(2)入射波波数η,即圆柱形孔洞的半径与入射波半波长之比;(3)h/R,即圆柱形孔洞至表面的距离与圆孔半径之比。当η较大时,地震动幅值变化激烈,位移幅值可出现跳动和放大的现象。当h/R增大至10～12时,位移幅值变化恢复至半空间的情况,表明圆柱形孔洞的影响可被忽略。

The problem of scattering of SH-waves by a buried cylindrical cavity and the ground motion is investigated at arbitrary incident angle in this paper. The displacement solution is constructed by applying the methods of complex function and multi-polar coordinates system. When wavelength of the incident wave is smaller compared with radius of the cylindrical cavity, the ground motion will be influenced greatly. There are three main factors that influence the ground motion. The first one is incident angle α0, the second one is incident wave number η, i.e. the ratio of radius of the cylindrical cavity to the half wavelength of incident wave, and the last one is h/R, that is the ratio of the distance of the center of the cylindrical cavity from the horizontal interface to the radius of the cylindrical cavity. When η is larger, the amplitude of the ground motion varies fiercely and sometimes will leap and enlarge sharply. If the value of h/R increases to 10-12, the variation of amplitude of the displacement recovers to that of half space, which shows that the influence of cylindrical cavity can be ignored.