Numerical Investigation of Ground-Borne Vibration Mitigation by Infilled Trenches in a Poroelastic Half-Space Considering the Moving Water Table

Abstract

The moving water table would vary soil layering and may significantly affect the isolation efficiency of wave barriers. A two-dimensional finite-element model is then developed using COMSOL to study the influence of the moving water table on the isolation efficiency of an in-filled trench. The effects of soil hydraulic properties, fill material characteristics, and geometrical parameters of the trench are investigated in detail. Numerical analyses show that a low permeability of poroelastic soil, which shows low-frequency behavior, would significantly reduce the screening performance of barriers. A resonance in stiff barriers may occur as the impedance ratio increases, resulting in worse isolation efficiency. Placing soft trenches in vibration-weakening zones results in worse screening effectiveness, while it is the opposite for stiff barriers. A single stiff barrier can hardly achieve a significant screening performance at the critical water table (Hc) because of the resonance in the dry layer. However, mounting a horizontal plate above Hc would efficiently mitigate the adverse effect of the resonance and improve the isolation efficiency of barriers.