深孔爆破技术在高地应力低透气性高瓦斯煤层增透防突中的适用性

Feasibility of deep-hole blasting technology for outburst prevention and permeability enhancement in high-gas-content coal seams with low-permeability subjected to high geo-stresses

同时考虑爆炸波、爆生气体、煤层原始瓦斯压力和煤层地应力的作用,对不同地应力条件下的高瓦斯低透气性煤层深孔爆破进行了有限差分动力数值模拟,并与室内相似模型实验和相关现场实践进行了对比。结果表明:地应力对煤层深孔爆破效果的影响显著,尤其对于高地应力煤层,地应力严重抑制着煤层爆生裂隙的扩展,煤层爆生裂隙半径随地应力的增大而近线性地减小,但深孔爆破技术对于高应力低透气性煤层仍可取得良好的增透效果;煤层地应力的主应力方向在一定程度上影响着爆生裂隙的扩展方向,实际工程需结合煤层地应力状况来布置爆破孔的空间位置。

By considering the action of blasting wave, explosion-induced gas and initial gas pressure as well as geo-stress endured by coal seam simultaneously, the deep-hole blasting in low-permeability high-gas-content coal seams under different geo-stresses were numerically simulated by using the FLAC3D code. And the simulated results were compared with the laboratory model test and other re- lated field studies on the permeability improvement of the low-permeability coal seams. The comparable analysis indicates that the geo-stress can dramatically inhibit the extension of the blast-induced cracks in the coal seams, especially for the deeply-buried coal seams. Though the radius of the blasting crack zones linearly decreases with the increasing of geo-stress, the blasting technique can also be adapted to enhance the permeability of the deeply-buried low-permeability coal seams. And the direction of the maximum geo-stress can affect the extension direction of the blast-induced cracks in some degree. Therefore, in a practical blasting engineering, the spatial location of the blast holes should be determined according to the state of the geo-stress endured by the coal seam.