Development of Longitudinal Cracks on Pavement over Shrinking Expansive Subgrade

ABSTRACT The volumetric change of expansive clays in pavement subgrade produces serious pavement distresses. Dry-land longitudinal cracking is one of the most prevalent pavement distresses due to expansive subgrade. However, the mechanism of the dry-land crack development has not been addressed in depth, and the propagation process of dry-land cracks has not yet been clarified. This paper investigates the mechanism of longitudinal crack developing at the pavement surface caused by expansive soils. The non-uniform matric suction change in the subgrade is simulated by a thermal expansion model in a finite element program, ABAQUS, to determine the shrinkage stresses in the subgrade soil and pavement structure. Numerical solution by the finite element program shows that the most likely location of shrinkage crack initiation in the subgrade is close to the pavement shoulder and close to the interface of the base and subgrade. Linear elastic fracture mechanics theory is used to analyze the crack propagation in the pavement. Compared to the fracture toughness of the pavement materials, the stress concentration at the initial shrinkage crack tip is large enough to drive the crack to propagate further. When the shrinkage crack propagates through the whole pavement structure, a longitudinal crack develops at the pavement surface close to the pavement shoulder.