Dynamic Responses of Ballastless Track with Damaged Cracks

In order to calculate the dynamic responses of damaged cracked slab track subjected to moving vehicular loads, a finite element model were established to represent the rail and the ballastless bed. The rail was modeled as linear viscoelastic discretely supported beam, while the ballastless bed was treated as linear viscoelastic continuously supported beam, and its damaged crack was simulated as the deterioration of the bending stiffness. Vehicle-track coupling dynamics theory and Hamilton principle were applied. A vertical dynamic coupling model of high-speed train and ballastless track was established, its dynamics equations were set up, and the track dynamics responses with the semi-cosine irregularity were calculated. Also, the effects of vehicle velocity and ballastless bed cracked location on the track dynamics responses were analyzed. The simulation results showed that ballastless bed with crack had a little effect on the rail dynamic responses but remarkable on the ballastless bed, and damaged ballastless bed dynamic responses get increased obviously with the vehicle velocity rising. Results also showed that the dynamic bending stress of the ballastless bed and the stress of the subgrade top face are larger when the crack located in the middle of ballastless bed.