Peridynamics-based analysis of damage initiation in airport rigid pavement under aircraft landing impact

In view of the damage initiation in airport rigid pavement induced by aircraft landing impact, a peridynamics (PD) model of airport rigid pavement that can simulate the spontaneous initiation and propagation of cracks in concrete slabs was developed based on the PD theory. By combining bond-based peridynamics with the energy equivalence thought of Hertz contact theory, a local tire-pavement impact contact model was established to characterize the nonlinear contact effect between the tire and the pavement. The developed model was validated through the Kalthoff-Winkler dynamic fracture test and the fracture model of an L-shaped concrete slab. Research results indicate that the simulated crack initiation angle (67.4°) and the fracture path are relatively consistent with classical experimental results, which verifies the applicability of the model to dynamic fracture and quasi-brittle fracture problems of concrete. Based on the model, the damage initiation laws of airport rigid pavement under different vertical sink velocities and slab thicknesses are further analyzed. At a relatively low vertical sink velocity (0.8 m·s^-1), the impact effect is mainly confined to the vicinity of the contact region; as the velocity increases, the tensile concentration at the slab bottom is significantly enhanced, and the high-stretch regions gradually expand and form potential microcrack nucleation zones; when the vertical sink velocity increases to 1.2 m·s^-1, the maximum bond breakage ratio reaches 9.6%. Increasing the slab thickness can improve the flexural stiffness of the pavement slab and reduce the proportion of high-stretch bonds at the slab bottom, thereby weakening the tensile concentration at the slab bottom under the impact effect. The PD model can effectively reflect the tendency of bottom cracks to propagate from the center to multiple directions under the impact effect. Although a single impact does not form a through crack, potential micro-damage zones have appeared at the slab bottom under a higher vertical velocity, which may further evolve into macroscopic cracks under repeated impact fatigue loads. The developed model does not require a preset crack path, and can provide references for damage identification, risk warning, and preventive maintenance decision-making in the touchdown zone of airport pavement.