Study on Damage and Failure of Backfill Induced by Stope Blasting and Control Technologies

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.