Study on the Void Structure Deterioration in the Rutting Zone of Porous Asphalt Pavement under Traffic Load based on the Discrete Element Method

In order to study the effect of traffic load on the void structure in the rutting zone of porous asphalt pavement, a virtual pavement model was constructed using the discrete element software PFC2D. The virtual rutting test on the two-dimensional discrete element model was conducted based on the static load equivalence principle to investigate the impact of different factors on the void structure deterioration in the pavement rutting zone. The results indicate that the greater the load, the greater the degree of compressive deformation in the void structure of the rutting zone. The void structure is rapidly compressed at the initial stage of load application, and after a prolonged load application, the pavement reaches a stable state that is essentially incompressible. The bonding capacity of asphalt is stronger at lower temperatures, and as the environmental temperature continues to rise approaching the asphalt's softening point, the deterioration degree of the void structure becomes severe. When the initial void ratio of the specimen is kept at a low level, the overall deterioration degree of the voids in the rutting zone is small. In contrast, specimens with higher void ratios experience greater void structure deterioration after loading, but the residual void ratio after the application of load still remains at a high level.