Optimization of relief hole blasting satisfying synergistic constraints of rock-breaking area and hole-bottom minimum burden

A strategy to optimize relief hole positions is proposed to enhance the effectiveness of tunnel blasting in rock breaking. This study employed two predefined arithmetic progressions to coordinate the distribution of rock-breaking areas and hole-bottom minimum burdens allocated to each row of holes. Iterative calculations were performed to determine the final position of each row of holes. To determine the optimal drilling scheme, modeling and simulation were conducted using a finite element method-smoothed particle hydrodynamics (FEM-SPH) coupling algorithm. This approach allowed for a comparison of the rock-breaking effects of relief holes under different constraint combinations. This study indicates that the displacement of rock particles varies in different depth zones. The largest displacements of the rock particles were observed in the middle of the charge section. For a conventional working face with a width of 12.2 m and a designed advance of 3 m, the rock-breaking efficiency is optimal when the two control ratios, rA and rW, are 1.5 and 1.4, respectively. This study advances the underground blasting design technology and contributes to energy reduction and efficiency improvements in blasting engineering.