Influence of cement asphalt mortar debonding on the damage distribution and mechanical responses of CRTS I prefabricated slab

•A 3-D FEM of prefabricated slab track with CA mortar debonding was established.•The damage distribution and mechanical responses of the slab were analyzed.•The situ test for rail supporting forces were carried out.•Under different train loads, the critical sizes of CA mortar debonding were proposed. The debonding between the prefabricated slab and CA mortar can result in very adverse effects on slab tracks, especially for shared passenger and freight railway services. We built a prefabricated slab track model based on the damage mechanics to research the effect of debonding on the concrete damage distribution and mechanical responses of prefabricated slabs. In this model, under various debonding cases, the upper surface damage distribution of the track slab near anchorages, vertical displacements of the slab end, and the maximum principle tensile stress of slab were calculated. The rail supporting forces tested in situ were employed as the train loads, which were measured by a Tekscan pressure measurement system. The results show that increasing the length and height of debonding can both promote the development speed and level of damage. Under the passenger train load, when the debonding extends to the 3rd anchorage with the height of 1.0 mm, completed damage appears on the slab surface. Meanwhile, the CA mortar void underneath the track slab can be formed, causing the displacement of the slab end not to rise with the increase of the debonding height. Under the freight train load, when debonding reaches to the 3rd anchorage, completed damage can also be obtained on the slab surface with debongding height of 0.8 mm. Furthermore, once this height exceeds 1.3 mm, the displacement change rate of the slab end rises as the debonding height increases once again, due to the generation of the second damaged zone. Considering the durability of slab track, once the size of debonding reaches the completed damage size for the prefabricated slab, the debonding should be repaired.