Influence of pore structure on the dynamic response of porous rocks under high strain-rate impact: A mesoscale numerical investigation

This study establishes a numerical simulation method for modeling the dynamic response of porous rocks under high strain-rate impacts and verifies its robustness, accuracy, and reproducibility. A systematic investigation was conducted to evaluate the effects of four pore structure parameters—porosity, pore size, aspect ratio, and orientation angle—on the dynamic response of rocks. The results indicate that increasing porosity significantly reduces normalized strength ( σ norm ), dynamic Young’s modulus ( E d ), and energy dissipation density ( U v ), with the degree of weakening influenced by pore geometry. A greater aspect ratio difference leads to higher U v , suggesting that more flattened pores promote complex fracture development and energy dissipation. Furthermore, the study reveals a coupled mechanism between pore structure and impact loading characteristics: Porosity exerts the most significant control on the rock’s impact response under different stress-wave loading conditions, whereas the effects of pore shape and size are comparatively secondary. For strength weakening, non-optimal loading periods ( T = 200 or 800 μs) are recommended to avoid the strengthening effect observed at T = 400 μs. To improve energy efficiency, the optimal loading period should be selected based on porosity. When porosity is less than 3%, applying an impact stress wave with an amplitude 12 times the rock matrix strength achieves an optimal balance between strength reduction and energy efficiency; when porosity exceeds 5%, an amplitude of 6 times the matrix strength yields superior energy utilization. The findings propose a porosity-driven impact loading design strategy, providing theoretical and quantitative guidance for field-scale engineering applications.