Dynamic Performances of CRTS Ⅲ Prefabricated Slab Track with Anti-vibration Structure in Subgrade-Tunnel Transition Section

In order to choose a proper length of the transition section and minimize negative impacts of the change of rail deflection between the subgrade-tunnel transition section on the track safety and the ride comfort, a vertical coupling dynamic model of CRTS Ⅲ slab track in subgrade-tunnel transition section was established using the finite element method and vehicle-track coupling dynamics theory. In this model, the change rate of rail deflection, vehicle acceleration, and wheel-rail force are taken as evaluation indexes to characterize the dynamic behavior of the system in the transition section. Through analysis, reasonable stiffness and layout of anti-vibration rubber pad is suggested for the transition section with the damping cushion set up both in subgrade and tunnel, and the length of transition section is proposed for the transition section with the damping cushion set up in tunnel only. The results indicate that a hierarchical stiffness of the anti-vibration rubber pad can be applied in the subgrade-tunnel transition section, and the stiffness ratio should be no more than 2. In order to ensure the running safety and reduce the workload of maintenance and repair in the subgrade-tunnel transition section, the length should be within the range of 25-30 m for controlling of the vertical acceleration of car body.