Evolution of Interface Performance of Longitudinal Ballastless Track Under Temperature Load After Embedded Steel Bars

In order to clarify the performance evolution of the interlayer interface of the longitudinal slab ballastless track under the temperature load, this study carried out the mechanical and fatigue performance tests of the interface after embedded steel bars of the composite specimen, and the load spectrum was generated by combining the temperature field monitoring data of the track slab on site. The spatial refined finite element model of ballastless track considering the whole process of interface damage was established and the stress state and damage characteristics of the interface between the lower layers under adverse temperature load were analyzed. The concept of initial temperature load of interface damage was introduced. The change in temperature load at the onset of damage at the interlayer interface after embedded steel bars was calculated and the evolution of debonding risk time after structural performance degradation was clarified. The results show that bearing capacity of the interlayer interface embedded with steel bar is significantly improved. The critical debonding failure displacement and the maximum load are increased by 76.38% and 153.41% respectively, and the fatigue performance is better, indicating that it is feasible to reduce the risk of interfacial debonding of ballastless track through embedding steel bars. The anchoring of embedded steel bars can not fundamentally limit the transmission of temperature force in the ballastless track and the damage suppression effect at the boundary of the slab is limited. It is easy to cause hidden damage near the reinforcement planting hole and the maximum damage value can reach 0.944. With the increase of service life,the initial temperature load that causes the initial damage of the interlayer interface decreases continuously. The safe temperature change range of good bonding state of the interface is reduced from 30.3 ℃ to 16.3 ℃. The number of days with possible interface damage risk is increased by 64.29% and the interlayer interface may have been damaged before extreme weather occurs. The railway department needs to adjust the temperature range of the concerned board based on the actual development of line diseases, and dynamically adjust the setting standards for maintenance thresholds.