Numerical Simulation on Ground Vibration Generated by Subway Train

摘要

The main objective of this study is to study ground vibration generated by subway train running in underground tunnel r constructed in clay area. A so called 2. 5D finite element method is adopted to simulate the wave generation and propagation r in the tunnel structure and ground with the assumption of invariant geometry and material distribution along the tunnel. r Finite element discretization is employed in cross section of the tunnel to represent the dynamic motions of the train r -track-tunnel structure and the surrounding soil medium ,and the train is simplified as a 1/4 car model. The load transfer r from rail to floating slab and to tunnel structure is carefully dealt with. The three-dimensional responses of ground are r obtained from the wave -number expansion by employing the in verse Fourier transform. Wave dissipation into far field is r dealt with the silent boundary constructed with the frequency-dependent dashpots , which has been proved quite effective to r absorb the outgoing waves from the inner finite element zone. The ground vibration features are revealed by illustrative case r studies of a simple 1/4 car model moving along track at variable speeds , tunnel depth and thickness, the amplitude and r wavelength of rail unevenness.