Viscoelasticity-Thermal Model And Crack Growth In Asphalt Concrete Pavement

Asphalt concrete pavement is widely used in highway construction. At the same time, there is a common phenomenon of pavement damage, especially the asphalt concrete pavement which includes initial crack. When the crack growth is serious, it even affects the service life. So it is very important to assess whether the micro or macro cracks in the structure will continue to expand. The viscoelastic properties of asphalt concrete pavement are obviously influenced by the ambient temperature. In the past, the influence of temperature on asphalt pavement is widely studied; however,the factors are not comprehensively studied, and the researches are not systematic.Further research is required for crack growth under different temperatures and dynamic loading conditions.Based on the theory of fracture mechanics and viscoelastic theory, theoretical analysis on the fracture and crack propagation is given. At the same time, it also provides a theoretical basis for the finite element simulation analysis of crack growth in pavement. By using the ABAQUS software, the model of pavement curved beam with initial crack is established. By introducing the extended finite element method,the static and dynamic analysis on the cracks in the structure of viscoelastic asphalt concrete pavement is carried out.In order to better reflect the actual pavement condition, the change of ambient temperature field is established by ABAQUS, the moving load is added by Dload subroutine, the prony series model is used to set the viscoelastic properties of asphalt mixture, and the material parameters of the simulation analysis are obtained by referring to the relevant test parameters. The effects of various factors on the crack is explored. The simulation results show that the stress around the crack tip increases with the decrease of the ambient temperature and the increase of the viscoelasticity.The velocity of the moving load has little effect on the stress around the crack tip. This conclusion is a good reflection on the actual situation.In order to discuss the pavement structure with initial crack, the different sizes of initial reflection cracks, different angles of inclined cracks, multiple reflection crack and surface crack model are simulated and analyzed. The influence of crack size,angle and distance on the stress field around the crack tip is studied. The results show that the stress is influenced obviously by the factors such as the size and distance, but the crack angle effect is little. Finally, the simulation results are analyzed in detail according to practical application.