Analysis of near-surface cracking under critical loading conditions using uncracked and cracked pavement models

In this paper, the mechanism of near-surface cracking under critical loading conditions was investigated using mechanistic modeling approaches. These loading conditions were represented by a combination of nonuniform tire contact stresses in three directions generated during vehicle maneuvers (free rolling, acceleration/braking, and cornering) that were predicted from a tire-pavement interaction model. Three-dimensional finite element models of uncracked and cracked pavements were developed to evaluate the critical factors that are responsible for crack initiation and propagation at the near-surface of a typical full-depth pavement structure. It was found that the near-surface cracks in the proximity of tire edges showed strong mixed-mode (tension and shear) fracture potential. The pavement responses from both uncracked and cracked pavement models indicated that shear mode of fracture in the presence of compression appeared to be the dominant mode of damage for near-surface cracking. Compared to the free rolling condition, tire braking/acceleration and cornering induced high tangential contact stresses on the pavement surface, which could significantly accelerate the development of cracks at the pavement near-surface. The near-surface cracking potential was dependent on the variations of localized tire contact stress distributions. The findings presented in this study shed light on the experimental characterization of the near-surface cracking phenomenon, which appears to be driven by different stress conditions than the classical bottom-up fatigue cracking. This study also highlights the impact of vehicle maneuvering on premature pavement damage that is often neglected in the current pavement design process.