Numerical Model of Asphalt Pavement Considering Transversely Isotropic Fatigue Damage

In order to study the fatigue damage in asphalt pavement, the damage that occurred in the tensile zone of pavement structure was assumed as being transversely isotropic. Based on this assumption, the asphalt pavement constitutive equation considering the transversely isotropic fatigue damage was derived. Then, using FORTRAN language to develop a material subroutine and a load subroutine, an ABAQUS finite element model of asphalt pavement was established based on the transversely isotropic fatigue damage theory. By analyzing the fatigue life of the model under different loads, the load-fatigue life curve was established in comparison with the test results to verify the reliability of the model. The distribution of damage degree and horizontal tensile stress in the pavement structure were studied by the finite element model. The results indicate that the fatigue damage mainly distributes at the base bottom near the middle line between the double wheels, where the fatigue crack appears first. With the load cycles increasing, the horizontal tensile stress decreases gradually, and its distribution in pavement structure changes. Its maximum position moves upward from the base bottom and transversely to the two sides from the middle line. The pavement life calculated by the proposed model is in good agreement with the experimental results, and the relative error is between 4.57% and 9.82%.