A multidomain indirect boundary element method (IBEM) is proposed to study the wave scattering of plane SH waves by complex local site in a layered half-space. The new method, using both the full-space and layered half-space Green's functions as its fundamental solutions can also be regarded as a coupled method of the full-space IBEM and half-space IBEM. First, the whole model is decomposed into independent closed regions and an opened layered half-space region with all of the irregular interfaces; then, fictitious uniformly distributed loads are applied separately on the boundaries of each region, and scattered fields of the closed regions and the opened layered half-space region are constructed by calculating the full-space and layered half-space Green's functions, respectively; finally, all of the regions are assembled to establish the linear algebraic system that arises from discretization. The densities of the distributed loads are determined directly by solving the algebraic system. The accuracy and capability of the new approach are verified extensively by comparing its results with those of published approaches for a class of hills, valleys and embedded inclusions. And the capability of the new method is further displayed when it is used to investigate a hill-triple layered valley-hill coupled topography in a multilayered half-space. All of the numerical calculations presented in this paper demonstrate that the new method is very suitable for solving multidomain coupled multilayered wave scattering problems with the merits of high accuracy and representing the scattered fields in different kinds of regions more reasonably and flexibly.

A special indirect boundary element method (IBEM) is proposed to investigate the waves scattering of plane P, SV, and SH waves by a 3D alluvial basin embedded in a multilayered half‐space. The new IBEM, which uses half‐space Green’s functions for uniformly distributed loads acting on an inclined plane as its fundamental solutions, has the merits of (1) excellent capability of dealing with the stratification of the basin and the external half‐space, (2) without the problem of singularity due to fictitious distributed loads being directly applied on the real boundaries, and (3) good adaptability to complex models with trapezoidal or triangular elements being used to discretize the boundaries. The validity and accuracy of the new method are verified by comparing its results with those in the literature. To illustrate the general applicability and efficiency of the new method further, 3D alluvial basins of varying shapes, depths, and sedimentary sequences embedded in a single layer overlying a homogeneous half‐space are numerically studied. Numerical results show that the basin’s shape, depth, and sedimentary sequence all have significant impact on the ground seismic responses; the incident angle also has noticeable effects on the surface motion, and these effects are more prominent at the observation points along the incident direction of the plane waves; for the case of layered model, the displacement spectral amplification is affected by the eigenmodes of the vibrations of the layers, both inside and outside the basin.