高瓦斯低透气性煤体定向聚能爆破增透机制

Increasing permeability mechanism using directional cumulative blasting in coal seams with high concentration of gas and low permeability

针对传统煤层预裂爆破增透存在的问题,对定向聚能爆破控制裂纹演化方向的理论和方法进行研究,即通过聚能射流的初始导向裂纹与后续高压气体形成的气楔联合作用,达到控制裂纹演化方向和长度的目的。基于模型试验和数值模拟,探讨了定向聚能爆破聚能方向和非聚能方向裂纹演化的机制。在潘三矿掘进工作面现场运用定向聚能爆破技术,达到增加煤体裂纹与保护围岩稳定性有机的统一。试验结果表明:爆破后3 h内抽采瓦斯量变化最为明显,其中最大抽采量是原始抽采量的470倍。有效抽采半径为7 m以内,爆破后顶板振幅约为0.23 cm。

In order to solve the problems of blasting to increase permeability in the coal seam, the methods of directional explosion with shaped charge are investigated. Jet of shaped charge penetrates the coal forming initial cracks and subsequently cracks are expanded by the wedge of explosive gas. The mechanisms of cracks of different directions are researched using numerical simulation and model tests. Through experiments on the work face of coal, it is proved that directional explosion with shaped achieve the aims of protecting roof and increasing cracks in demanding direction. The experiment results show that the change of gas drainage volume is most obvious in 3 hours after blasting; and maximum gas drainage volume is 470 times the original volume. The effective radius of gas drainage is within 7 meters; meanwhile the roof vibration amplitude is about 0.23 centimeters.