3D Modeling of Transition Zone between Ballasted and Ballastless High-Speed Railway Track

Abstract

In design and construction stages of the railway track, engineers try to avoid situations wherein track stiffness changes abruptly. Nevertheless, changing the track stiffness is inevitable, especially in the transition zone where the conventional ballasted track connects to modern ballastless track systems. In this area, track stiffness changes abruptly and it causes differential settlement, which is the main cause for degradation of tracks and foundations. Numbers of remedies have been constructed to reduce the sudden change of stiffness in transition area. The emphasis of this study is held on the assessment of the behavior of two types of the transition zones under the train moving loads. For that reason, the dynamic effect of the transition, including the displacement, acceleration and stress distribution of each part of transitions, should be analyzed. Therefore, a 3D finite element model is developed to investigate the behavior of the transition zone in response to passage of high-speed trains. The results of the dynamic analysis of a transition zone without applying any remedy have been compared with two common applicable remedies. Firstly, by installing the auxiliary rails along the ballasted and ballastless tracks, and secondly gradually increasing the length of the sleepers in ballasted area.