Mechanical response of flexible asphalt pavement under large temperature difference and temperatures during four seasons

Semi-rigid base asphalt pavements in Xinjiang suffer from various defects, particularly reflection cracks caused by extreme environmental conditions and dynamic vehicle loads. Adopting a flexible asphalt pavement is effective in inhibiting reflection cracks. In this study, asphalt pavement structures with three typical flexible bases were selected for numerical simulation under the coupled fields of a dynamic load and the actual environmental conditions in Xinjiang (high-, low-, and large-temperature-difference areas) using ANSYS. Heat transfer systems and heat radiation conditions were established based on an investigation of the temperature variations in typical high- and low-temperature areas. Simulations were conducted to establish the temperature field within the internal structure. A half-sine wave model was used to simulate the dynamic vehicle load, and a coupled field was established. The tensile strain, tensile stress, shear stress of the asphalt layer, shear stress of the graded gravel layer, vertical compressive strain at the top of the subgrade, and surface deflection were adopted to analyze the mechanical response under the coupled fields. According to the simulation results, the variations in tensile strain, shear stress of the asphalt layer, and shear stress of the graded gravel layer were 8.45 %-26.52 %, 38.38 %-52.96 %, and 12.66 %-20.65 %, respectively, in high-temperature areas. Increasing the asphalt layer thickness can significantly reduce the amplitude of the variation and peak value of the mechanical index of the pavement structure. At high temperature differences of 30 °C, 40 °C, and 50 °C, the maximum peak values of the asphalt layer tensile stress were 4–8 MPa. A summer climate can increase the shear stress in the asphalt layer by more than 30 %. These results support the application of flexible bases in asphalt pavements in complex external environments.