Macro-micro mechanisms of void formation and grouting strength reinforcement in concrete pavement slabs using FEM-DEM coupling method

Growing traffic and heavier vehicle loads cause voids beneath concrete pavement, significantly degrading road performance and safety. This study aimed to investigate the mechanical behavior of concrete pavement with voids and evaluate the effectiveness of grouting reinforcement. Researchers calibrated concrete surface and base layer parameters using uniaxial compression simulations and then developed a numerical model of concrete pavement void formation utilizing the FEM-DEM coupling method. The structure experienced initial cracking at approximately 76.6 kN, the load continued to increase to a peak of 139 kN, and after the peak the curve entered a descending branch, indicating that the structure began to degrade after reaching its ultimate bearing capacity. Analysis of displacement, crack patterns, and force chains revealed shear bands developing on either side of the void. A simulated grouting reinforcement, using 9,800 particles (0.5 mm diameter), demonstrated significant improvement, with the peak strength reaching 220 kN, representing a 58.3% increase. Enhanced load transmission, crack and displacement distribution, and force chain transfer confirmed the effectiveness of grouting in strengthening structural performance. This research provides vital theoretical support for addressing concrete pavement void issues.