Experimental study on interface performance of CRTS Ⅱ slab ballastless track under temperature loading

Interlayer interface damage poses a prevalent challenge in China Railway Track System (CRTS) Ⅱ slab ballastless tracks, with temperature playing a pivotal role in its occurrence. This study aims to scrutinize the mechanism of interlayer interface damage of track structure under temperature loading, vertical full-scale composite specimens were constructed for push-out and normal-tension model tests, and digital image correlation (DIC) technology was adopted to obtain the interlayer strain field distribution during loading and to get the mechanical property degradation, damage evolution law and damage mechanism of cement asphalt (CA) mortar layer interface under different temperatures. Based on the experimental study and fracture mechanics, the temperature cohesion damage model of the track slab-CA mortar interlayer interface was established. The results show that the bonding surface between the track slab and CA mortar layer is particularly susceptible to damage, and the interface damage exhibits "cold brittleness" and " thermal ductility" at low and high temperatures, respectively. Cohesion zone models (CZM) were constructed for both the normal and tangential interfaces at temperatures of 0 °C, 15 °C, 30 °C, 45 °C, and 60 °C. Furthermore, by defining field variables in the ABAQUS software, a temperature variation function describing key parameters of interface damage fracture behavior was integrated into the CZM, using defined field variables. The simulation results exhibited excellent agreement with the experimental findings.