Simulation on surface crack propagation process in steel bridge deck pavement subjected to hydrodynamic pressure on the mesoscopic scale

The surface crack of the steel bridge deck pavement (SBDP) will further expand under the action of hydrodynamic pressure, resulting in water damage of SBDP. To study the process of "initiation-expansion-failure" of surface crack in SBDP under hydrodynamic pressure on the mesoscopic scale, the fluid-solid coupling algorithm was compiled based on the discrete element method (DEM). The permeability coefficient of asphalt mixture was calculated and compared with the existing laboratory test results, and the appropriate meso-hydraulic parameters were selected. Then the number and distribution of meso-cracks after 30,000 times of hydrodynamic pressure were used as indicators to describe the process of surface crack propagation. After that, the effects of vehicle speed and surface crack size were studied. Finally, the failure states of single-layer and double-layer pavement structures were compared and analyzed. Results show that, the development of meso-cracks shows a two-stage trend of slow growth and rapid development, which is leaping, and the expansion of the surface crack will occur only when the hydrodynamic action can accumulate to a certain extent. Meanwhile, the vehicle speed will promote the expansion of surface crack under hydrodynamic pressure. After that, the depth of the surface crack is constant, and the larger the width, the greater the impact on the surface crack propagation of SBDP in the early stage, but the smaller the water damage after 30,000 times of hydrodynamic pressure. Finally, the double-layer pavement structure can better prevent external water from infiltrating and corroding the steel bridge deck.