Interlayer Cracks Evolution in Slab Ballastless Track Based on Acoustic Emission Technology

［Objective］ Slab ballastless track is a typical layered structure system, and the bonding state of its interlayer interface directly affects the safety of train operation. Therefore, it is necessary to study the interlayer evolution of slab ballastless track by combining micro and macro methods. ［Method］ Concrete-mortar composite specimens are made and partial are anchored with embedded bars. Acoustic emission technology is used to carry out interface normal performance tests on the composite specimens. The entire failure process of composite specimens is monitored by the acoustic emission monitoring system, and the macroscopic load-time curve during the evolution of interlayer interface cracks and the microscopic acoustic emission cumulative ringing count index of the cracks are obtained respectively. ［Result & Conclusion］ The interlayer interface debonding failure process can be divided into three stages: the interface engagement stage, the crack stable expansion stage, and the interface instability break stage. After rebar implantation, both the displacement value of the composite specimen interlayer interface debonding failure and the corresponding acoustic emission ringing count during the debonding failure process are increased significantly. The acoustic emission technology can be used to evaluate the state of the interlayer interface scientifically, and it is verified from both the macro and micro levels that the rebar implantation can effectively increase the bonding performance of the composite specimen interface.