Numerical analysis of the effects of subgrade settlement on top-down cracking in epoxy asphalt pavement

Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads. A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking (TDC). The contour integral method is utilized to calculate the stress intensity factor (SIF) at the crack tip, and then the extended finite element method (XFEM) is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading. The results of these analyses indicate that increased subgrade settlement, stiffer surface layers, and softer bases will increase the SIF, resulting in a faster crack propagation rate. It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt mixtures. However, when the base layer modulus is higher than 12500 MPa, the increase in surface modulus can decrease crack propagation length. Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation. The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.