煤矿井巷中空孔掏槽爆破模型实验研究

Model test of empty hole cut blasting in coal mine rock drivage

针对煤矿硬岩巷道掘进掏槽爆破效果差的问题,通过模型实验研究了不同直径中心空孔掏槽腔体的爆破破坏形式。从掏槽爆破腔体体积、岩石爆破块度等方面进行对比分析,并采用高速摄影系统观测不同空孔直径下掏槽爆破腔体的抛掷过程。试验结果表明:随着空孔直径的增加,爆破掏槽深度越深,掏槽腔体的破坏半径越小,槽腔体体积越小,岩石块度越来越小。空孔直径较小时,爆破后大块度碎石占的比例较大。从高速摄影结果可以直观看出,大空孔掏槽爆破抛掷过程比较"收敛",掏槽腔体碎石抛掷速度均值为18.9 m/s;小空孔掏槽爆破抛掷过程比较"开放",掏槽腔体碎石抛掷速度均值为9.2 m/s;前者是后者的两倍。

In view of the problem of the cut blasting effect is not good of the hard rock roadway excavation in coal mine,the model experiment is used as a research tool to study the failure mode of the slot cavity with different diameter of center empty holes,the test results were compared and analyzed form the aspects of cavity volume and blasting block size,and slot cavity throwing process with different empty hole diameter have observed by using high speed camera system. Test results show that: with the increase of the diameter of the empty holes,the deeper the cut depth is,the smaller the damage radius is,the smaller the size of the cavity is; the empty hole diameter is smaller,the larger proportion of the large size of the gravel,with the increase of the empty hole diameter,the rock mass is smaller and smaller;from the high-speed photography can be seen directly,the throwing process of big empty hole cutting is"convergence",mean throwing velocity of slot cavity gravel is 18.9 m/s; the throwing process of small empty hole cutting is "open",mean throwing velocity of slot cavity gravel is 9.2 m/s,and the former velocity is about two times as fast as the latter.