A numerical study of vibration isolation for rail traffic

摘要

This paper presents a numerical study of vibration isolating measures for rail traffic. The focus is on thernmeasures that are taken at the source side, where flexible materials are incorporated in the track structure.rnTypicle examples of such measures are under sleeper mats or ballast mats. It is shown how a numericalrnmodel for the prediction of railway induced vibrations provides a valuable tool for the evaluation of thesernmeasures. The model fully accounts for the interaction between the vehicle, the track and the soil. The track-soilrninteraction is modelled by means of an analytical model for the track and a boundary element methodrnfor the soil, based on the Green's functions of a horizontally layered halfspace. When the track is assumedrnto be invariant in the longitudinal direction, integral transformation methods allow for an efficient solutionrnprocedure in the frequency-wavenumber domain. The model is applied to investigate the influence of arnresilient slab mat in a slab track on the response of the track and in the free field. The track compliance andrntransfer functions between the track and the free field are compared to those in the case where no isolationrnis applied. The incorporation of a slab mat introduces a resonance of the track superstructure on the resilientrnslab mat at a track resonance frequency. At frequencies higher than this frequency, the radiation of wavesrnfrom the track in the free field is effectively reduced. In a narrow frequency band around the track resonancernfrequency, however, the free field response increases due to the presence of the slab mat.