复式楔形深孔掏槽爆破研究

Investigation of cut blasting with duplex wedge deep holes

掏槽爆破时随炮孔深度增加,岩石夹制作用增强,抛掷效果差,导致炮孔利用率降低,直接影响岩巷的掘进速度.采用数值方法对12孔复式楔形掏槽进行研究,揭示了应力波在槽腔内的传播规律,再现了炮孔底部槽腔的形成过程.研究发现采用双楔形毫秒延期爆破,炮孔底部形成2个应力峰值,有利于槽腔内岩体的破碎.同时中心孔的存在增强了破碎岩体的抛掷作用,提高了炮眼利用率.根据分析结果进行了孔深3m的现场爆破试验,10组爆破实验平均炮眼利用率为94.9%.

With the depth increase of cut blasting holes, the clamping effect of rockmass be- comes manifested, leading to poor throw of rock fragments and low utility of blast holes, which directly influences the rate of roadway drivage in rocks. In this study, a duplex wedge cut blasting with 12 holes is studied by numerical method. The simulation results reveal the propagation of stress waves in the hollow cavities and the formation process of cavities at the bottom of the blasting holes, where two stress peaks are formed, which makes the crushing of the rock much effective. The presence of the center hole enhances the throw of the broken rocks, and improves the utilization efficiency of blasting holes. In situ blasting tests were car- ried out with a blasting hole of 3 m deep. An average utility of 94.9 % of the blasting holes was achieved in 10 tests.