煤巷掘进中预裂爆破对抽放提高的分析

The analysis on pre-splitting blasting to improve permeability draining rate in heading excavation

针对低透气性煤层掘进工作面瓦斯预抽率较低以致突出危险较高的问题,以某矿(K1、K4)煤层煤巷掘进工作面为研究对象,进行了现场深孔预裂爆破试验,对预裂爆破前后钻孔瓦斯抽放量进行了对比分析,并对预裂爆破后有效的钻孔瓦斯抽放半径进行了考察。试验结果表明:K1煤层预裂爆破后瓦斯预抽率仅需10d就能达到37.13%,缩短抽放时间60%;而且效果检验5个循环才出现瓦斯解吸指标超标。K4煤层预裂爆破后瓦斯预抽率仅需12d就能达到34.28%,缩短抽放时间60%;而且效果检验3个循环才出现瓦斯解吸指标超标,预裂爆破对瓦斯抽放效果有明显的提高;爆破后K1和K4煤层瓦斯有效抽放半径分别为4.5和5.2m。这对于现场预裂爆破工作具有一定的指导意义。

Aiming at the problem of low excavation speed and high risk of coal and gas outburst because of low gas draining rate in heading excavation,and taking an excavation heading of a mine for example,the test of deep-hole pre-splitting blasting is processed.The amount of gas draining after pre-splitting is compared with the amount of direct draining,and the effective radius of draining is surveyed.The test result shows that the draining rate of K1 coal seam reaches 37.13 %,which reduces the draining time by 60%,10 days after pre-splitting,and the gas desorption index exceeds the standards until the fifth blasting.The draining rate of K4 needs 12 days to reach 34.28 %,which reduces the draining time by 60%,and the gas desorption index exceeds the standards when the third blasting processes.Obviously,the effect of gas draining is improved by pre-splitting blasting.The effective draining radius of K1 and K4 are 4.5 and 5.2 m respectively after pre-splitting blasting.The research can provide reference for the fieldwork of pre-splitting blasting.