多缝线金属射流定向预裂爆破技术在瓦斯抽采中的应用

Application of multi-seam metal jet directed pre-split blasting technology in gas extraction

为提高高瓦斯、高应力、低透气性煤层钻孔瓦斯抽采能力,开发了多缝线金属射流定向预裂爆破技术,并在常村矿N1-3采区进行了预裂爆破增透工程试验。爆破过程中,多缝线金属射流首先在煤层中射出主裂缝,随后推进剂延迟爆破产生高能爆生气体压裂煤体,破坏坚硬煤体的致密结构,在钻孔周围形成松动裂隙圈,达到煤层增渗效果。试验结果表明:钻孔瓦斯抽采浓度由措施前的10.1%增加到措施后的42.2%,钻孔瓦斯抽采流量由措施前的0.026 m3/min增加到措施后的0.077 m3/min,百米钻孔瓦斯涌出量和煤层透气性系数也分别提高近1倍,掘进速度由措施前的49.5 m/月提高到了措施后的130 m/月。

To improve gas extraction efficiency of low permeability coal ,the authors developed multi-seam metal jet directed pre-splitting blasting technology, and did engineering experiment on pre-split blasting in the N1-3 of Changcun Mine. In blasting,coal seams could achieve the aim of antireflection effect through projecting main cracks, producing high energy explosive gas to break coal body by delaying propellant blasting, destroying dense structure of hard coal body, and forming loose slit ring around holes. Experimental results show that the average concentration of gas extraction increases from 10. 1% to 42.2%, the average discharge of gas extraction increases from 0. 026 m3/min to 0. 077 m3/min,and the tunneling speed is enhanced from 49.5 m/month to 130 m/month,the gas emission of holes and the permeability of coal seam improves nearly double.