低透气煤层深孔预裂聚能爆破增透试验研究

Experimental Study on Permeability Improvement of Deep Hole Pre-splitting Cumulative Blasting in Low Permeability Coal Seam

为了提高深孔预裂爆破增透的效果,基于相似模拟理论,建立低透气煤层深孔预裂爆破的试验模型,利用相似材料配比加工制备试样,试样包含4个控制孔和1个爆破孔,并采用聚能药包进行爆破模拟试验。通过监测煤层的应变信号,分析爆破载荷作用下试样的裂纹扩展特性。结果表明:爆破试样在爆炸压缩荷载作用会产生反向拉伸卸载波,造成爆破试样的裂纹扩展,沿聚能药包方向有明显侵彻效果。现场试验表明在经过深孔预裂聚能爆破增透后的煤层瓦斯抽采浓度为原来的1.18～3.05倍,瓦斯抽采流量是爆破前的1.2～3.3倍,抽采半径达到了4.5 m。

In order to improve the permeability improvement effect of deep hole pre-splitting blasting,based on the similarity simulation theory,the experimental model of deep hole pre-splitting blasting of low permeability coal seam was established,and the sample was prepared by using the proportion of similar materials.By monitoring the strain signal of coal seam,the crack propagation characteristics of samples under blasting loading are analyzed.The results show that the blasting sample will produce reverse tension unloading wave under the action of explosion compression load,which will cause the crack expansion of the blasting sample and have obvious penetration effect along the direction of energy collecting charge.Field tests showed that the concentration of gas extraction in the coal seam after permeability improvement by pre-splitting cumulative blasting through deep hole was 1.18 to 3.05 times of the original,the gas extraction flow was 1.2 to 3.3 times of that before blasting,and the extraction radius was 4.5 m.