● Systematic LS-DYNA simulation investigates empty hole number/spacing effects on bucket cut cavity formation, quantifying blasting damage-compensation space coupling. ● Unveils empty holes’ dual effects (stress concentration, crack guidance); a =200 mm achieves optimal cavity-forming efficiency with balanced energy use and surrounding rock protection. ● Field tests validate CB-r5-a200: 2 m × 2 m, 10 m deep inclined branch ore pass gains regular contour and precise main pass connection. ● Provides key design parameters/references for small-section inclined raise single-stage blasting, enabling efficient, safe shaft sinking in confined underground spaces. Branch ore passes are typically constructed in confined underground spaces where traditional blasting methods suffer from low efficiency, safety concerns, and high costs. Achieving precise single-stage blasting raise sinking while minimizing surrounding rock disturbance in such settings remains a significant challenge. This study investigates the construction of an inclined branched ore pass in the Datun Tin Mine, Yunnan, China. Using LS-DYNA numerical simulation, we systematically analyzed the influence of the number of relief holes and their spacing on cavity formation effectiveness for cylinder cut blasting under the site's stratigraphic conditions. Comparative analysis of six schemes revealed that for a given cut area, an optimal number of relief holes exists, which makes the post-blast relief hole compensation space approximate the design value; increasing the number beyond this optimum yields diminishing returns. The scheme with five relief holes demonstrated the best cavity formation effect when the spacing was 200 mm. Based on simulations, a field trial of single-stage blasting raise sinking was conducted for a 2 m × 2 m cross-section, 10 m-deep inclined branch ore pass. The resulting raise contour met specifications with smooth walls and achieved precise integration with the main ore pass system. The successful application provides critical design parameters and practical evidence for the single-stage blasting raise sinking of small cross-section inclined ore passes.
Wang et al. (Wed,) studied this question.