Near-Surface Pavement Failure under Multiaxial Stress State in Thick Asphalt Pavement

The failure of pavement near its surface (rutting and cracking) is a complex phenomenon affected by vehicular loading and pavement structure. This paper documents the investigation of near-surface failure in thick asphalt pavement by using a developed three-dimensional (3-D) finite element (FE) model and Mohr–Coulomb failure criterion. The FE model incorporates measured 3-D tire–pavement contact stresses, hot-mix asphalt (HMA) linear viscoelasticity, continuously moving load, and implicit dynamic analysis. The multiaxial stress states (normal and shear stress) near the pavement surface under measured stresses from tire contact and from moving wheel load are presented. The failure potential of pavement near the surface was evaluated by comparing the multiaxial stress states predicted from the FE model to the Mohr–Coulomb failure criterion. The authors suggest that the cracking could start at the pavement's surface within the area between dual tires. This paper presents several conclusions about surface-initiated cracking potential: (a) it increases as the temperature increases; (b) at high temperatures, the shear-induced surface cracking could start from some distance below the pavement surface in conjunction with the distortional deformation; (c) compared with the 3-D tire contact stress, the uniform contact stress distribution underestimates the pavement failure potential near the surface, especially at high temperatures; (d) the negative temperature gradient in the HMA layer induces a greater failure potential at the pavement near-surface compared with the constant average temperature case; and (e) the debonding under the surface layer significantly increases the shear stress at relatively low normal stress and leads to premature failure around the interface compared with the full bonding case.