Mining blasting operations improve extraction efficiency while simultaneously causing substantial dynamic damage to adjacent backfill structures, which significantly threatens working face stability, especially during secondary mining operations. This study investigates the damage evolution mechanisms of backfill materials under blasting effects and optimizes blasting parameters for backfill protection using LS-DYNA for numerical simulations based on explosion dynamics principles. The numerical analysis examines four parallel perimeter hole spacing configurations (0.2 m, 0.4 m, 0.6 m, 0.8 m) and four protective layer thickness schemes (0.3 m, 0.4 m, 0.5 m, 0.6 m). A systematic analysis was conducted of damage distribution patterns, failure mechanisms, and stress-wave attenuation characteristics at rock-backfill interfaces across varying parameters, using a damage variable threshold of ≥0.6 as the failure criterion. Results demonstrate that stress waves undergo significant attenuation at rock-backfill interfaces due to pronounced differences in elastic modulus between the materials.Both increasing parallel perimeter hole spacing and increasing the reserved protective layer thickness induce an exponential reduction in backfill damage. When parallel perimeter hole spacing of the backfill exceeds 0.8 m, or the reserved protective layer thickness of the fan holes reaches 0.6 m, the backfill exhibits minimal damage with markedly improved stability. Field validations at Chambishi Copper Mine′s 1040-1-4# stope, implementing optimized blasting parameters, confirmed their engineering feasibility. These outcomes establish theoretical foundations and practical guidelines for optimizing underground blasting and preserving backfill.

In mine excavation blasting engineering, smooth blasting typically uses detonating cords to transmit the explosion. This process has low construction efficiency, consumes a significant amount of blasting equipment, and increases the mine′s production costs. To solve this problem, the sympathetic characteristics of explosives can be utilized to initiate detonation within holes. A research method that combines experiments on emulsion explosives′ sympathetic detonation under various confinement materials with numerical simulations of the sympathetic detonation process in rocks is adopted. By analyzing the impact of confinement conditions, decoupling coefficients, and other factors on the sympathetic detonation distance of explosives, the stable sympathetic detonation distances of emulsion explosives with varying diameters and lengths in boreholes are identified. The conclusions are as follows: confinement conditions significantly influence the sympathetic detonation distance of explosives, with improved confinement resulting in a greater sympathetic detonation range. Under a specific radial uncoupling coefficient, the diameter of the explosive exerts a minor influence on the sympathetic detonation distance, which increases as the charge diameter enlarges. Additionally, the sympathetic detonation distance diminishes with an increase in the radial uncoupling coefficient and extends with the length of the explosive charge. Industrial trials were conducted to verify the findings, with the explosive spacing set at 70 cm. The results indicate that, in comparison to the conventional construction method utilizing detonating cord, the cost of blasting materials for smooth blasting in roof holes was diminished by 33.1 yuan per meter, representing a reduction of 36.1%.