裂纹闭合对高压空气爆破冲击煤体瓦斯抽采效果影响

鉴于高压空气爆破冲击煤体过程中裂纹闭合对瓦斯抽采效果的影响,基于能量和弹性理论,对裂纹闭合的长度进行分析计算,得到了闭合区域位置在距离爆破孔3.8 m。通过在丁集煤矿进行井下现场试验,结果表明:裂纹的闭合对该区域的瓦斯抽采影响表现为闭合区域瓦斯的涌出量增幅变小;在距离爆破孔1.0~4.0 m的区域内,随着距离爆破孔距离的增加观测孔瓦斯的涌出量增幅先增大后减小;在距离爆破孔1.8~2.5 m的区域内,瓦斯涌出量增幅最大;在距离爆破孔4.0 m区域,瓦斯涌出量增幅最小,接近裂纹闭合区域。理论计算和现场试验具有良好的一致性。

Effect of crack closure on the gas drainage efficiency during the impact coal seam with high pressure air blasting

The crack closure in an impact coal seam induced by the high pressure air blasting has a great effect on the gas drainage efficiency.The length of crack closure was calculated and analyzed based on the energy and elastic theories.And,it was found that the closure region is located at the distance of 3.8 m from blasting hole.The high pressure air blasting experiment was conducted in the Dingji underground coal mine,China.The results show that the effect of crack closure on gas drainage efficiency was manifested as the amplitude of gas emission decreases at the crack closure region.In the region of 1.0-4.0 m from blasting hole,the amplitude of gas emission in observation hole was first increased and then decreased with the increase of distance from blasting hole.In the region of 1.8-2.5 m from blasting hole,the amplitude of gas emission was maximal.At the region of distance 4.0 m from blasting hole,the crack was nearly closed that the gas emission in observation hole was minimal.The theoretical calculation is in a good consistency with the field test,and it can provide an important reference for the reasonable arrangement of gas drainage boreholes.