The influence of interlayer voids on the mechanical behavior of semi-rigid base asphalt pavement based on continuous-discrete coupled simulation

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The long-term service of semi-rigid base asphalt pavements often leads to the formation of interlayer voids, a distress mode that is more severe than conventional debonding. This study employed a continuous-discrete coupled model to systematically investigate the influence of void width, void height, and material modulus on pavement mechanical behavior. The results indicate that increasing the void width markedly elevates interlayer shear stress and induces a transverse tensile stress zone at the bottom of the overlying layer, promoting simultaneous crack propagation in both transverse and upward directions. Conversely, as void height increases, the interlayer shear stress and the tensile stress zone diminish, allowing the pavement structure to settle into a new, relatively stable equilibrium state. Additionally, increasing the modulus of the lower surface layer effectively reduces both transverse tensile and shear stresses, thereby mitigating further void deterioration. These findings elucidate the complex mechanical responses induced by interlayer voids and offer theoretical guidance for improving structural design and prolonging the service life of asphalt pavements.