Screening Effects of Open Trenches to Ground Vibrations Induced by High-speed Trains on a Poroelastic Half-space

An analytical model is proposed to investigate the screening effects of trenches to the train-induced ground vibrations in three-dimensional conditions. A fully saturated poroelastic half space is firstly utilized to model the ground. Placed on the top of the poroelastic half-space,the embankment and soil banks beside the trenches are modelled as elastic layers with appropriate widths. The rails and sleepers are modelled as Euler beams and an anisotropic Kirchhoff plate,respectively. Biot's theory is applied to characterize the fully saturated poroelastic half-space, considering the coupling between the soil skeleton and the fluid. The governing equations are solved in the transformed domain based on Fourier transforms and Fourier series; the time domain results can be obtained by the fast Fourier transform(FFT). Numerical examples are given for a moving x2000 train that operates on the saturated poroelastic half-space. The influences of coupling effect between soil skeleton and pore water on the screening efficiency of the trench are investigated. Furthermore, the screening effects of open trenches on the poroelastic half-space are compared with that of trenches on the single-phase elastic half-space. It is found that the single-phase elastic half-space model will underestimate the screening effect of the trench significantly for supercritical train speeds.