Abstract: Based on the scaled boundary coordinate transformation of scaling splicing lines, an improved scaled boundary finite element method is proposed to accurately model the layered half-space, and a high-precision analysis model for the scattering field response of a complex layered site is established in the frequency domain. This method adopts the splicing lines as scaling center, which overcomes the difficulty due to the scaling requirements, and extends the scope of application of the scaled boundary element method to horizontal and inclined layered sites. Furthermore, based on the modified scaled boundary element method, a solution model for the complex layered half-space scattering field is established. In this model, the substructure method is used to transform the scattering problem with complex boundary conditions into the soil-structure interaction problem, which reduces the complexity of the seismic wave scattering problem. This transformation is strictly true in linearly elastic range. The accuracy of the proposed model is verified by comparing with the reference examples. In addition, the scattering field response of the canyon-underground cavity system in horizontally layered site is conducted. The results show that, compared with the case of no cavity under the canyon, the underground cavity will amplify the scattering displacement amplitude of the canyon surface, and this amplification effect is more obvious for the square cavity.

Key words: scattering field, scaled boundary finite element method, layered site, canyon-underground cavity system, soil-structure interaction