Effects of loading, geometry and material properties on fracture parameters of a pavement containing top-down and bottom-up cracks

In this paper, the fracture parameters of top-down and bottom-up cracks initiated in a multi-layer asphalt pavement is computed numerically. Using extensive two-dimensional finite element analyses, the effect of thickness and stiffness of concrete layer and base layers, length and number of cracks, and vehicle position relative to the crack plane was investigated on fracture parameters of both top-down and bottom-up cracks. It was shown that the position of front and rear wheels have great influence on the values of stress intensity factors (KI and KII) and T-stress, such that magnitude and sign of these three parameters may change significantly by moving the vehicle from the far distances towards the crack and then passing the wheels from it. The critical condition of fracture parameters is occurred where any of front and rear wheels were very close to the crack. The change in fracture parameters is more pronounced for thinner and stiffer values of overlay. In general, top-down crack is more vulnerable to propagate, since the corresponding values of KI, KII and T are significantly higher than the values of bottom-up crack. The value of KII component was not generally sensitive to the change in thickness and stiffness of pavements layers.