Track vibration analysis for railways with mixed passenger and freight traffic

Abstract

By means of establishing the continuous elastic three layer beam model for track structures with random irregularity of the track vertical profile, a methodology of analysing track vibration by Fourier transform technique is presented. First, the vibration equations of the track structure 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 structure are obtained by performing inverse Fast Fourier Transform. As an application example, vibration analysis of the track for railways with mixed passenger and freight traffic is carried out. Influences of different speeds of passenger and freight trains and different line grades of the track irregularity on track vibration are investigated. The studies show that the worst situation for railways with mixed passenger and freight traffic is from freight trains. The track displacement and the track acceleration as well as the track dynamic forces on the ground resulting from freight traffic are larger by 54—57, 39—47, and 52—56 per cent, respectively than those from the passenger trains when both passenger and freight trains are running at the same speed. Also, the irregularity of the track vertical profile has great impact on track vibration. With the development of track irregularity, dynamic responses induced by freight trains increase more rapidly than those induced by passenger trains.