Abstract: This paper is focused on scattering and diffraction of Rayleigh wave caused by local topographies. For this purpose, a substructure replacement technique based on the theory of soil-structure interaction is used to evaluate the effects of canyon, vertical fault fracture zones and mountains on scattering and diffraction of Rayleigh wave. Based on the substructure theory, the scattering problem is decomposed into three parts: solving the dynamic stiffness of the ground of excavation, solving the dynamic stiffness of the complex structure and solving the input wave of the free field. The dynamic stiffness of the ground of excavation and the complex structure are solved using scaled boundary finite element method (SBFEM). In order to validate the proposed method, two examples are solved and the results are in good agreement with those reported in the literature. Then the scattering of Rayleigh waves by a variety of complex terrains, such as canyons, vertical faults and mountains are analyzed. Numerical results are presented in graphical form for the surface displacement and displacement spectra. Conclusions in this study can be useful in engineering practice. The proposed method can be applied to the design of seismic isolation ditch and seismic adaptability analysis of dam and bridge.

Key words: Rayleigh wave, complex sites, SBFEM, substructure method, dynamic soil-structure interaction