Effects of subgrade differential settlement on dynamic response of vehicle and damage behavior of slab track

The differential settlement of subgrade, which is an important problem in the operation of high-speed railway. In order to study the effects of subgrade differential settlement on the service performance of CRTS II slab track and the stability of train operation, a vehicle–slab track–subgrade system coupling dynamic model was established. The concrete damage of track structure was considered based on damage mechanics theory. Dynamic simulations were carried out using the proposed model. The results show that the subgrade differential settlement will increase the dynamic response of the vehicle system. The dynamic response of the vehicle system is positively correlated with the settlement amplitude. The acceleration of vehicle body and the rate of wheel load reduction are sensitive to the subgrade settlement within the settlement wavelength ranging from 10 m to 20 m. Under the subgrade differential settlement and the dynamic action of the vehicles, concrete damage occurs earlier in the supporting layer and the concrete damage variable of the supporting layer is larger compared to the precast slab.