The effect of increasing train speed on track transition performance

摘要

The goal of this research was to study the responses of the track structure elements when increasing the train speed. Therefore, a comparison between low speed values (earlier cases) and high speed ones has been conducted. In addition, the influence of distance between the slab track and the first sleeper on ballast track has been analysed. The finite element analysis supplies graphical and numerical data to the study. The analysis shows that increasing train speed has a negative influence on ballast layer. In fact, a slightly increase in transient vertical displacements and transient vertical stresses amplitude is shown. That means that train speed is an important factor in transient stresses and displacements in sleepers and ballast layer. A separation between sleeper and slab track seems to be detrimental to transient vertical displacements and stresses under sleepers in the transition zone. Results have shown that, more separation between slab and the first sleeper means a slightly increase in transient amplitude in vertical displacements as well as, in vertical stresses under sleepers. Results also showed that when the train goes from slab to ballast, a discontinuity appears in slab track structure, as if the train pushes softly into the slab in this area when running in this direction.