Research on stress and cracking characteristics of high-speed railway asphalt concrete under complex loads

Considering that asphalt concrete layer of high-speed railway under complex load may cause interlayer separation and cracking, which results in the instability of roadbed, a viscoelastic cohesion model was established to simulate the complex interactions between the bottom slab and the asphalt layer, including bonding, debonding, separation, and cracking. A three-dimensional refined finite element model of the vehicle-track-subgrade was established. The contact parameters between the layers were obtained using field push plate tests. The correctness of the model was verified by the dynamic displacement data of the bed surface. The mechanical properties and crack propagation types of asphalt concrete layer under complex load were analyzed. The results show that under the effect of positive temperature gradient, the temperature sensitive area is located at the corner of the effective contact area of the bottom slab. Under the effect of negative temperature gradient, the maximum stress and strain are small, and the temperature sensitive area is in the middle of the effective contact area of the bottom slab. When the temperature drops sharply, the crack growth is mainly open-type cracks. Low-temperature or high-temperature field-train load coupling is prone to lateral slip cracks. The composite geomembrane with length of 1.0-1.5 m can effectively control the gap between layers and crack propagation at the expansion joint position. © 2020, Central South University Press. All right reserved.