Modelling of Floating-Slab Track with Discontinuous Slab Part 1: Response to Oscillating Moving Loads

摘要

This paper presents three different methods for modelling a track with discontinuous slab under oscillating moving loads. These are the Fourier-Repeating-unit method, the Periodic-Fourier method and the Modified-phase method. The first two methods, borrowed from the literature of periodic infinite structures, are accurate if careful consideration is taken when performing numerical integrations. The third method, not presented elsewhere before, is faster and simpler; it is only valid for velocities of moving loads lower than the critical velocity of the track, but this "velocity effect" is of no consequence for underground railways. Discontinuity of slab provides a parametric excitation for moving loads over floating-slab tracks. It is shown that in the frequency range of ground-borne vibration, more vibration propagates form such tracks at resonance frequencies of the slabs, compared with tracks with continuous slabs. It is found that the velocity effect is insignificant when calculating displacements of a typical floating-slab track under oscillating moving loads with velocities less than 100km/hr. However, a correction has to be made to account for the right phase between the input force and the output displacement.