Impact of debonding between layers of ballastless turnouts on the vibration characteristics of the wheel-rail system

The mortar layer of the slab ballastless turnout is the weakest connecting part compared to the rest of the structure, meaning debonding between the turnout slab and the mortar layer is prone to occur under the dynamic load of a train. In order to study the impact of debonding on the vibration response of the wheel-rail system in the turnout area, a rigid-flexible vehicle-turnout coupled dynamic model that takes debonding into account was established based on the theory of vehicle-track coupled dynamics; the flexible deformation of the multi-rail and turnout slab was also included in the model. The impact of debonding on the wheel load transition and the vibration acceleration of the turnout structure and axle box were then analysed. The results show that: There are significant differences in the impact of different types of debonding on the vibration response of the vehicle-track coupled system. When the debonding height is less than the voiding limit, the impact of the debonding height is significant, while the vibration acceleration of the vehicle-turnout system remains basically unchanged once debonding height reaches the void limit.