低透气性煤层松动爆破增透效应研究

松动爆破是防治瓦斯突出的有效措施。针对煤层透气性差,突出危险预测指标高的问题,采用松动爆破技术对煤层进行卸压增透。结合某矿工作面煤体和爆破参数,理论计算了爆破后裂隙圈范围,主要包括应力波作用和静压破坏作用两部分,分别为0.41 m和1.47 m;通过布置钻孔并观测瓦斯流量变化,裂隙圈范围与理论计算较为接近,略小于应力波和静压破坏两部分理论计算之和;在理论计算和现场观测的基础上,确定合理的钻孔间距为3 m。采煤工作面经卸压爆破后,突出预测指标S(钻屑量)和q(瓦斯涌出初速度)分别下降了16.7%和57.1%,有效降低了工作面突出危险性。

Study on Permeability Increase of Loosening Blasting in Low Permeability Coal Seam

Loosening blasting is an effective measure to prevent gas outburst.Aiming at the problem of low per-meability of coal seam and high risk prediction index,the loosening blasting technology is adopted to increase the permeability and pressure unloading of coal seam.Combined with the coal body and blasting parameters of a certain mine working face,the theory calculates the range of fracture circle after blasting,mainly including stress wave action and static pressure damage,0.41 m and 1.47 m respectively.By arranging boreholes and observing the change of gas flow,the fracture circle range is relatively close to the theoretical calculation,and it is slightly smaller than the two parts of theoretical calculation.Based on theoretical calculation and field observation,reasonable drilling spacing is determined.After the blasting of the coal mining face,the outburst prediction index S and the initial velocity of gas e-mission q decreased by 16.7% and 57.1% respectively,which effectively reduced the outburst danger of the working face.