Numerical simulation of rock damage evolution induced by dual-hole shaped charge blasting under in-situ stresses

This study investigates the dynamic mechanical response and damage evolution of rock during dual-hole shaped charge blasting under in-situ stress conditions. Three-dimensional numerical models for bilateral-groove-slot shaped charge blasting in dual-borehole rocks were established, incorporating a rock dynamic damage constitutive model based on an improved Mohr-Coulomb criterion. The results indicate that the increase in uniform in-situ stress leads to a reduction in both the main crack length and the damage in the non-shaped charge direction. When the centerline connecting the two boreholes aligns at a 0° angle with the horizontal direction, an increase in the lateral pressure coefficient K significantly enhances the main crack length and the inter-hole breakthrough effect. The fluctuation in the inter-hole effective stress time history curve intensifies, with an average increase in peak stress of 21.9 % and 27.6 %, respectively. Conversely, when the centerline aligns at a 45° angle, an increase in K exhibits an inhibiting effect on main crack extension and inter-hole breakthrough. The stress time history curve displays more pronounced instability in fluctuation magnitude, with an average increase in peak stress of 8.1 % and 25.4 %, respectively. Furthermore, the overall damage under the 0° configuration exhibits a positive correlation with K for K=0.5-1.5, while it decreases as K increases from 1.5 to 2.0. This observed trend is inverse to that found under the 45° configuration. The research results offer a design basis and theoretical guidance for shaped charge blasting operations under diverse in-situ stress conditions.