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.