Numerical Fracture Analysis of Reflective Cracks in Asphalt Overlays Subjected to Traffic Loading

Cracking of asphalt layers and pavements is one of the most common modes of failure in roads and highways, which can signicantly increase the cost of repair and rehabilitation. Since asphalt mixtures can behave as brittle materials at low temperature, brittle fracture and crack growth in pavements is usually observed at the surface of roads located in cold regions. Trac loading, (due to the weight of moving vehicles) and thermal stress (induced by daily or seasonal variations of eld temperature), are two major parameters aecting nucleation and propagation of cracks inside the pavements. Re- ective cracking is often observed in the overlays, and the growth of such cracks is a an important problem in this eld. Thus, understanding the mechanism of crack growth is essential for predicting pavement performance for designing the averlay thickness, as well as in the design and optimization of mixtures. In this study, a twodimensional multi-layer asphalt pavement containing a re ective crack, and subjected to trac loading of the front and rear wheels of a moving vehicle, was analyzed numerically using ABAQUS nite element code. Three fracture parameters, including modes I and II stress intensity factors (KIandKII ) and the T-stress, are computed for various positions of the vehicle relative to the re ective crack. In the analyzed models, the in uence of some parameters, such as wheel positions relative to the crack, elastic modulus, thickness of layers and crack length, was studied on the sign and magnitude of fracture parameters. According to the obtained results, an asphalt layer containing a vertical re ective crack experiences dierent mixed mode opening-sliding (mixed mode I/II) deformations when a vehicle moves from far distances towards the crack location. It was observed that a wide range of positive and negative KI ;KII and T-stress values is induced in the asphalt layer. The in- uence of crack length on the fracture behavior of the analyzed crack was also noticeable.