Eyebrow damage control for ring blasting based on detonation sequence optimization

Brow damage control in ring blasting is essential for ensuring roof stability in mining roadways. However, previous studies have largely focused on rock fragmentation at the borehole bottom, with limited attention to cracks near the collar. This study investigates brow damage mitigation through optimization of the detonation sequence. The damage mechanism was first analyzed theoretically based on stress field distribution. Numerical simulations of ring blasting under different detonation sequences were then performed using ANSYS/LS-DYNA, followed by field validation of the findings. Results indicate that the stress field end effect along the detonation direction depends on both detonation distance and the number of simultaneously initiated holes. Simultaneous initiation of multiple holes creates a splitting effect between ring holes, isolating the blasting zone from the surrounding rock and reducing damage to the reserved rock. In delayed detonation, damage induced by earlier-initiated holes guides the damage propagation of subsequent blastholes. Optimal brow damage control was achieved by initiating the central three holes first, followed by the side holes, and field tests confirmed that it significantly improves brow integrity. This study provides practical guidance for enhancing brow integrity and safety protocols in roadway ring blasting.