中凯矿业大直径深孔爆破落矿装药结构优化研究

Optimization Study by Zhongkai Mining on Charge Structure of Large-diameter and Deep-hole Blasting

装药结构对厚大矿体大直径深孔爆破落矿效果具有重要影响。中凯矿业帮中矿区现行装药结构(空气间隔长度比例24.2%)存在爆破后冲破坏作用严重的问题,造成后一排炮孔堵塞、坍塌甚至报废,严重影响生产效率;而盲目增大空气间隔长度比例则存在爆破大块率增加的风险。以矿山实际的炸药和岩石参数为基础,采用数值模拟软件LSDYNA开展大直径深孔爆破落矿装药结构优化研究。选择常用空气间隔器作为间隔材料,以空气间隔长度比例为研究对象设计了12种装药结构方案进行数值模拟,得到了装药结构与爆破后冲作用、大块率、自由面质点振动峰值速度以及峰值有效应力等评价指标之间的关系。结果表明:自由面质点振动峰值速度以及峰值有效应力随空气间隔长度比例增加逐渐下降;当空气间隔长度比例小于等于30.5%时后冲作用明显,后排炮孔可能出现塌孔现象,当空气间隔长度比例大于等于45.3%时,存在大块率增加的风险,最优装药结构的空气间隔长度比例为44.2%。现场深孔爆破落矿试验表明,优化的装药结构爆破后大块率为7.1%且爆破后冲作用得到有效控制。

Charge structure has an important impact on deep hole blasting efect with a large diameter in thick and large ore bodies.The current charge structure(24.2%air deck length)used in Bangzhong mine of Zhongkai Mining has a serious problem of post-blast impact damage,resulting in blockage,collapse or even scrapping of the latter row of holes,which seriously affects productivity.However,blindly increasing the air deck length ratio has the risk of increasing the boulder yield.Based on the actual explosives and rock parameters of the mine,a study on char-ging structure optimization was carried out by using the numerical simulation software LSDYNA.The commonly used air spacers were selected as the deck materials.Then,12 charging structure solutions were designed for numerical simulation with respect to the air deck length ratio,and the relationships between the charging structure and the eval-uation indexes(such as the back impact effect,boulder yield,peak particle velocity of free surface and peak effective stress)were obtained.The results show that the peak particle velocity of the free surface and the peak effective stress gradually decrease with the increase of the air deck length ratio.The back impact effect is obvious and the back row of holes may collapse when the air deck length ratio is less than or equal to 30.5%.There is a risk that the boulder yield increases when the air deck length ratio is greater than or equal to 45.3%.The optimal air deck length ratio is 44.2%.The deep hole blasting tests show that the boulder yield of the optimized charge structure is 7.1%,and the back impact effect has been effectively controlled.