A two-step time simulation of ground vibrations induced by the railway traffic

Abstract

Recent decades have been fertile in terms of development of vehicle dynamics simulations. But the usual applications dedicated to the train design rarely take into account ground vibrations. In order to assess the influence of vehicle dynamics on track deflection and therefore on ground wave propagation, the vehicle/track system must be studied globally. The track/soil coupling is first investigated, through various track/soil models. From there, a decoupled approach is proposed, which proves valid as far as the soil is sufficiently rigid with respect to the ballast. It works in two stages: the simulation of the vehicle/track subsystem provides in a first step the ground forces, considering the irregularities of the rail as the excitation mechanism. The resulting forces are then applied, in a second step, to the soil subsystem model. Two applications are presented, consisting of the passing of a tram over a local discontinuity and the passing of a high-speed train over a rough track. The results obtained show a good agreement with experimental measurements as well as the importance of the whole vehicle/track/soil dynamics on the level of ground vibration.