A new indirect boundary integral equation method (IBIEM) is developed to solve the seismic wave scattering problem in a three-dimensional fluid-saturated layered half-space. Based on Biot's theory, the Green's functions of inclined circular loads in porous elastic layered half-space are firstly deduced. According to the single-layer potential theory, when establishing the scattered wave field, the uniform surface loads and fluid sources are located directly on the boundary surfaces of the scatterers, so as to avoid determining the optimal location of fictitious wave sources surface. At the same time, the radiation condition of wave in semi-infinite layered media can be accurately realized by using the dynamic Green's function of concentrated load, and the computational memory can be greatly reduced. The scattering of seismic waves by a canyon topography in saturated layered half-space is examined in detail. The numerical results indicate that with the increase of the porosity of the overlying soil, the amplitude of surface displacement can be amplified by 1∼6 times, and the amplification effect is more significant near the corner of the canyon, which can be attributed to the superposition of wave diffraction effect and resonance amplification effect of saturated soil layer.

开发了一种新的间接边界积分方程方法（IBIEM）来解决三维流体饱和层状半空间中的地震波散射问题。基于Biot理论，首次推导出多孔弹性层状半空间斜圆周载荷的格林函数。根据单层势理论，在建立散射波场时，均匀地表载荷和流体源直接位于散射体的边界面上，从而避免确定虚拟波源表面的最佳位置。同时，利用集中载荷的动态格林函数，可以准确地实现波在半无限层状介质中的辐射条件，大大减少计算内存。详细研究了饱和层状半空间中峡谷地形对地震波的散射。数值结果表明，随着上覆土孔隙度的增加，地表位移幅度可放大1～6倍，且在峡谷拐角处放大效果更显着，这归因于饱和土层的波衍射效应与共振放大效应的叠加。