The evolution law of void disease in concrete pavement based on falling weight deflectometer

This study analyzes the dynamic deflection, stress, and strain responses of cement concrete pavement under different void positions, areas, shapes, surface layer parameters, and Falling Weight Deflectometer loads, based on a three-dimensional solid model of the void area in cement concrete pavement. Results show that the void position has a significant impact. For slab corner voids, the deflection presents a semi-sinusoidal variation with a lagging peak. For slab edge voids, the deflection increases monotonically with the void area. For slab center voids, the deflection is insensitive to the void area, and the damage exhibits cumulative and irreversible characteristics. Among the surface layer parameters, an increase in elastic modulus reduces the deflection and strain at all positions (while increasing the stress at slab edges and centers). An increase in thickness consistently reduces the deflection and strain (with a slight increase in stress at slab centers). And changes in Poisson’s ratio have a negligible effect on the responses. The influence of void shape varies by position: rectangular voids tend to cause high stress concentration, while oval and polygonal voids result in better (more favorable) responses. This study provides a theoretical foundation for void disease assessment based on multi-dimensional mechanical parameters. For slab corner voids, max deflection linear with void area, max stress decreases then rises, max strain evolves in 4 stages. For slab edge/center void, edge has monotonic deflection & 3-stage strain; center shows slight deflection, dispersed stress & decrease-increase-decrease strain. All voids’ mechanical parameters rise linearly with FWD load, but differ in mechanisms: corner (stress concentration), edge (cantilever), center (global bending).