Numerical simulation of mixed fracture in asphalt mixture based on SCB test

The fracture properties of asphalt mixture are one of the primary factors influencing cracking in asphalt pavements. The cracking condition of asphalt pavements is typically the result of a combination of multiple fracture modes, making it difficult to accurately describe with a single mode I or mode II fracture mode alone. To address the complex cracking patterns of asphalt mixtures, an extended finite element model was established based on the semi-circular bend (SCB) test. By varying the support and initial crack positions, the crack propagation trends and stress distributions under mode I, mode II, and mode I-II mixed-mode fractures in asphalt mixtures were investigated. The results indicated that the crack propagation paths predicted by the model aligned well with the experimental observations. Specimens always initiated cracking at the tip of the preset crack and extended along a certain path towards the loading point until failure occurred. The location of the braces affected the path of crack propagation. The crack tip stress of the mixed fracture was approximately 2.8 times that of the single type. Furthermore, the influence of the preset crack length on the cracking of the asphalt mixture was studied. It was found that the crack length only affected the cracking location of the model and did not affect the crack propagation path.