Towards an improved prediction of asphalt pavement rutting through thermal-mechanical coupled constitutive modelling

To predict accurately the evolution of asphalt pavement rutting, an advanced numerical modelling process was proposed and successfully implemented through the finite element software ABAQUS. In the process, a thermal-visco-elastic-plastic constitutive model for asphalt mixture was derived into numerical form and compiled using the user-defined material subroutine (UMAT). To apply realistic traffic loading, a mathematical form of loading model was proposed according to the tire-pavement interaction and realised through the user-defined load subroutine (DLOAD). Besides, a heat transfer model was calculated before the mechanical calculation, and the results of the pavement temperature field were used as the boundary condition for the mechanical calculation. A few case simulations were conducted using the numerical process and the results indicate that the severe rutting at pavement intersections or parking lots is due to not only the longer loading time but also the deeper plastic deformation region. In addition, the numerical model is capable of quantitatively identifying the critical temperature at which the pavement rutting starts to grow rapidly; accordingly, a new criterion for taking strategies to avoid or slow down the rutting distress of the pavement can be proposed, which is of great significance for the practice.