Numerical Investigation of Vibration Reduction of Ballast Track with Asphalt Trackbed over Soft Subgrade

摘要

A methodology of analyzing track vibration by Fourier transform technique is presented. It offers a means of establishing the four layer continuous elastic beam model for vibration analysis of ballast track with asphalt trackbed. The random irregularity of the vertical railway surface is considered and the asphalt trackbed is simulated as Euler beam with resistant bending modulus. First, the vibration equations of the ballast track are transformed by Fourier transform. The vibration displacements in Fourier transform domain are solved with this transformed equation. Then, the vibration responses of the track are obtained by performing inverse Fast Fourier Transform. As an application example, analysis of vibration reduction of ballast track with asphalt trackbed over soft subgrade is presented. Influences of different asphalt thicknesses and different rubber contents as well as different soft subgrade moduli on track vibration are investigated. The studies show that the use of asphalt trackbeds as a substitute for sub-ballast in conventional ballast track with soft subgrade can significantly reduce the deflections and accelerations of the rail, tie, ballast and asphalt and the pressures on the subgrade. For deflections and accelerations of the rail, tie, ballast and asphalt the maximum reduction can be up to 14.1% and 18.6% respectively compared with the conventional ballast track with soft subgrade. The maximum reductions of pressures on the subgrade can be up to 14%.