Mechanical Analysis of Asphalt Pavement with Rigid Base in View of Viscoelastic–Viscoplastic Damage Theory

Asphalt pavement on rigid base (cement concrete) differs significantly from traditional granular base pavement. To investigate its mechanical behavior, a viscoelastic–viscoplastic damage constitutive model for asphalt mixtures is proposed and verified. A user-material subroutine (UMAT) is developed to implement the model, and a three-dimensional finite element model is established to analyze pavement responses under various working conditions. Key numerical results include the following: the asphalt layer primarily experiences compressive–shear failure, with peak shear stress (τ12) reaching 141.6 kPa under rigid base conditions; emergency braking increases τ12 to approximately 270.3 kPa, a 91% increase; increasing vehicle speed from 15 m/s to 35 m/s raises τ12 by 36.7%; based on stress analysis alone, the recommended asphalt layer thickness is between 0.10 m and 0.14 m, as thickness beyond 0.10 m yields diminishing stress reduction. The findings provide references for performance prediction, structural design, and material development of asphalt pavement on a rigid base.