Fracture mechanics analysis of rock containing collinear cracks under dynamic blasting loads

Based on the superposition principle of fracture dynamics, the disturbance caused by dynamic blasting loads on the expansion of primary cracks in a typical slope was examined in this study. The stress intensity factor of the collinear double crack tip under the condition of mixed-mode dynamic and static loading was calculated. A dynamic response evaluation index was established, and the influence rules of blasting load amplitude, crack inclination angle, crack length, and crack spacing were analyzed theoretically. A collinear double-crack combination model was established and operated using ABAQUS software. The dynamic blasting load is shown to markedly increase crack propagation. Cracks with a 45° inclination angle are most intensely affected by the dynamic load. The crack length increases continuously as new cracks emerge under static load conditions; the dynamic load accelerates the penetration of the crack system. When the crack spacing is small, the penetration between them occurs more quickly. When the crack spacing increases to 10 mm, the unit shows multiple single crack failure modes. Response surface methodology was applied to obtain the multiple regression fitting function, which validates the theoretical analysis results. This work may provide a valuable reference for similar projects.