液态CO2爆破煤层增透最优钻孔参数研究

 爆破钻孔参数的选取是消除爆破空白区域、提高爆破增透和瓦斯抽采效果的关键。监测液态CO2爆破过程中爆破器主管内高压气体压力时程曲线，研究液态CO2爆破煤层增透机制，并建立FLAC3D数值模型，研究结果表明：在水平层理上，单孔液态CO2爆破有效影响半径为出气孔方向6 m和出气孔法向4 m；控制孔明显增加多孔连续爆破裂隙区范围。采用数学计算和数值模拟2种方法确定多孔连续爆破最优钻孔参数为：爆破器间距5 m和爆破孔间距7.5 m。进行井下液态CO2爆破试验，爆破后煤层透气性系数提高17.49～22.76倍，瓦斯抽采浓度提高3.16倍，瓦斯抽采混量提高1.71倍。合理选取液态CO2爆破钻孔参数，为井下节约爆破成本和达到最佳爆破效果提供参考。

Research on optimal borehole parameters of antireflection incoal seam by liquid CO2 blasting

The selection of blasting borehole parameters is a key to eliminate the blasting blank area and to improve effects of blasting antireflection and gas extraction. In the process of liquid CO2 blasting，the curve of pressure-time process in the main pipe blasting was monitored. The principle of liquid CO2 blasting was studied and a FLAC3D numerical model was established. The results showed that the effective radius of single hole blasting was 6 m and 4 m along and normal to the direction of the vent hole in the horizontal bedding respectively. The control hole increased obviously the range of fracturing area under multi hole continuous blasting. Mathematical calculations and numerical simulation were adapted to identify optimal borehole parameters of multi hole continuous blasting. The spacing of blasting device and the blast hole spacing were determined as 5 m and 7.5 m respectively. The results of experiment on liquid CO2 blasting underground indicated that the permeability of coal seam increased by 17.49–22.76 times，and that the gas extraction concentration and mixed flux increased by 3.16 times and 1.71 times respectively. Optimal selection for borehole parameters of liquid CO2 blasting helped to save cost and achieve the best effect of blasting.