A refined fictitious-pile-method to evaluate the vibration mitigation effect of pile arrays in a layered half-space

This study focuses on the mitigation of ground-borne vibrations with a frequency range of 1–80 Hz by pile arrays, consistent with typical rail transit systems. A refined fictitious pile method is therefore developed to calculate vibration mitigation performance of pile arrays in horizontally stratified soils. The proposed semi-analytical framework accurately captures wave scattering at the pile–soil interface without relying on periodic or symmetric simplifications. It enables the simulation of arbitrarily distributed pile arrays with varying dimensions and material properties. The thin-layer method is applied to calculate the Green’s function for a layered half-space in the space–frequency domain, eliminating the need for double discrete Fourier transforms of spatial coordinates. Consequently, the proposed method demonstrates superior computational efficiency. The validation of the proposed approach was conducted through comparative analysis with existing numerical methods. Numerical studies reveal the interplay between Bragg scattering and local resonance mechanisms, highlighting the influence of pile dimensions and array characteristics on vibration mitigation performance. Soil stratification exhibits a significant influence on the mitigation performance of pile arrays. Detailed dispersion analysis and circular interface statistical interference mapping elucidate the underlying physical phenomena governing the formation of isolation bands.