Performance evolution of self-compacting concrete for ballastless track based on high-cycle fatigue damage constitutive model

The self-compacting concrete (SCC) filling layer of CRTS III ballastless track is prone to high-cycle fatigue damage under repeated train loads and complex environments. Based on the technology that fully couples damage and finite elements, a fatigue damage analytical method of SCC for the CRTS III ballastless track was established, which discussed how train load change, initial deterioration, and slab end debonding would affect the performance evolution of the filling layer. It is found that the fully-coupled method can reveal the interaction between fatigue damage and the structure's stress field. As the train load changes, the damage of the filling layer during the service period accumulates pretty much following Miner's rule in the first place. However, when the initial stress level reaches around 0.33, the fatigue damage of the filling layer presents nonlinear accumulation with the increase of loading times. Therefore, the fully-coupled method at this time can better reflect the time-varying features of the structure. Compared with initial deterioration of the SCC filling layer and the change of train loads, slab end debonding has a more prominent effect on damage accumulation.