无底柱分段崩落法扇形炮孔爆破机理研究与应用

实验研究了试件强度与抵抗线对无底柱分段崩落法扇形炮孔爆破效果的影响,分析了有效爆破区域出现在孔底部位而不是孔口部位的原因,揭示了扇形炮孔爆破的方向性与顺势破坏效应,据此讨论了炮孔密集系数的合理取值范围以及孔底起爆的适用条件等;应用试验结果改进北氵名河铁矿扇形中深炮孔的装药结构与起爆顺序,试验区大块率从3·0%降低到1·8%·并杜绝了爆破“隔墙”现象的发生·

The Blasting Mechanism of Fan-Patterned Holes and Its Application in Sublevel Caving

Experiments were conducted to investigate the effects of material strength and hole burden on the blast performance of fan-patterned holes in sublevel caving, and to analyze the factors affecting the effective area of blasting. Two important revelations were made in this study: (1) blasts with fan drilling exhibit a strong directionality, and (2) better fragmentation occurs in the hole-bottom region of the fan-patterned holes, where the hole spacing is larger, than in the collar region, where the spacing is smaller. The second phenomenon can be explained by the sequential effect of breakage, that is, between-hole breakage occurs first in the collar region where the spacing between holes is small. Based on the experiment results and conclusions drawn, the effective range of hole density coefficient and the application condition of hole-bottom detonation are discussed. The experimental results were applied to improve the load structure of charges and the sequence of detonation in Beiminghe iron mine. The percentage of oversized lumps of the blasted ore in the mine was lowered to 1.8% from 3.0% and the occurrence of partition wall was successfully eliminated.