Modelling of Floating-Slab Track with Discontinuous Slab

Abstract

A floating-slab track with discontinuous slab provides a spatially-varying stiffness under a constant moving load. When a train moves on such a track, even with the absence of rail roughness, a parametric excitation develops as wheels move up and down applying dynamic forces at the wheel-rail interface. The dynamic force is magnified if one of its principal frequencies matches with any of the train or the track resonance frequencies.In this paper, a new method based on a Fourier series representation is developed to couple a moving train to a track with discontinuous slab. A two-degree-of-freedom system is used to model a quarter of a train with four axles and two bogies moving on a track with constant velocity. The purpose of this work is to investigate the dynamic effect of slab discontinuity on trains running in underground railway tunnels, where the velocity is less than 100km/hr. For typical parameters of a train and a track, it is found that the force at the wheel-rail interface is only increased by 1% of its static value due to slab discontinuity. However, the dynamic effect may be more important in circumstances where high-speed or heavy-axled trains are used in underground tunnels.