School of Energy Science and Engineering, Henan Polytechnic University
State and Local Joint Engineering Laboratory for Gas Drainage & Ground Control of Deep Mines, Henan Polytechnic University
Department of Mining Engineering, West Virginia University
Jiulishan Coal Mine, Henan Coking Coal Energy Co., Ltd.

长壁采空区卸压瓦斯抽采是煤矿绿色开采技术体系中煤与瓦斯共采的重要组成部分，在覆岩内布置水平定向长钻孔抽采卸压瓦斯近年来应用较多；与高抽巷、普通高位钻孔不同，其在采动覆岩内布置抽采时，对覆岩破坏及瓦斯运移的响应与敏感性具有显著的特殊性。通过理论分析、数值模拟与工程实例验证等方法研究了采动覆岩内水平定向长钻孔的位置特征与卸压瓦斯抽采机理。阐述了水平定向长钻孔抽采卸压瓦斯的技术原理，结合室内试验、数值模拟分析了水平定向长钻孔的3个位置特征：① 钻孔布置位置区域瓦斯积聚程度高，为钻孔抽采瓦斯提供浓度条件；② 钻孔布置位置区域裂隙较为发育，为钻孔抽采提供瓦斯源保障；③ 钻孔布置位置区域岩层受采动影响较小，为钻孔提供稳定性条件。在此基础上，从采动裂隙内瓦斯积聚程度、采动岩层渗透率和采动钻孔稳定性3个方面揭示了水平定向长钻孔布置抽采机理，提出了水平定向长钻孔的位置判据，给出了确定钻孔抽采位置的方法流程，并通过数值模拟、工程实例进行了合理性验证。研究结果表明：依据钻孔位置判据进行钻孔布置抽采的最大瓦斯抽采纯量达2.59 m3/min，为其他对比钻孔的2.56倍；在定向长钻孔抽采作用下，回风巷最大瓦斯体积分数为0.11%～0.72%，风排瓦斯量为0.69～2.79 m3/min，验证了按照钻孔位置确定方法进行钻孔布置抽采的合理性。研究成果可对矿井布置水平定向长钻孔抽采采空区卸压瓦斯提供技术依据，进而提高矿井卸压瓦斯抽采率、促进煤矿绿色开采技术发展。

The pressure-relief gas drainage in longwall mining goaf is an important part of the simultaneous extraction of coal and gas in the green mining technology system. The horizontal-directional long boreholes arranged in overlying strata for pressure-relief gas drainage have been widely used in recent years. The boreholes in mining overburden are different from the high drainage roadway and ordinary high-level boreholes. When the pressure-relief gas is extracted from the overburden of goaf, the boreholes response and sensitivity to the mining overburden damage and gas migration have some significant particularities. Through theoretical analysis, numerical simulation and engineering example verification, the position characteristics and pressure-relief gas drainage mechanism of horizontal-directional long boreholes in mining overburden were studied. The technical principle of extracting pressure-relief gas by horizontal-directional long boreholes was described. Combined with laboratory tests and numerical simulation, three position characteristics of hori-zontal-directional long boreholes were analyzed. The gas accumulation degree at the borehole area is high, which provides the concentration conditions for borehole gas drainage. The fractures at the borehole area are relatively developed, which provides gas source guarantee for borehole drainage. The stratum at the borehole area is less affected by mining, which provides stability conditions for the borehole. On this basis, the drainage mechanism of horizontal-directional long boreholes was revealed from three aspects: the degree of gas accumulation in mining fractures, the permeability of mining strata and the stability of mining boreholes. The theoretical criteria for determining the position of horizontal-directional long boreholes was proposed, and the method for determining the position of the boreholes drainage was given, which were verified by numerical simulation and engineering examples. The research results show that according to the borehole position criteria, the maximum pure volume of gas drainage of the borehole arranged is 2.59 m3/min, which is 2.56 times that of other comparative boreholes. Affected by horizontal-directional long boreholes drainage, the maximum gas volume fraction in return airway is 0.11%−0.72%, and the gas volume is 0.69−2.79 m3/min, which verifies the reasonability of pressure-relief gas drainage based on the position determination method of horizontal-directional long boreholes. The research results can provide a technical basis for the layout of horizontal-directional long boreholes to extract the pressure-relief gas in goaf, thereby improving the pres-sure-relief gas extraction rate and promoting the development of green mining technology of the mine.

国家自然科学基金重点资助项目(U21A20108)；国家自然科学基金资助项目(U1704131)；深井瓦斯抽采与围岩控制技术国家地方联合工程实验室开放基金资助项目(SJF2201)

郭明杰，郭文兵，赵高博，等. 长壁开采覆岩内水平定向长钻孔位置特征与卸压瓦斯抽采机理[J]. 煤炭学报，2023，48(10)：3750−3765.

GUO Mingjie，GUO Wenbing，ZHAO Gaobo，et al. Position characteristics of horizontal-directional long boreholes in overlying strata and drainage mechanism of pressure-relief gas in longwall mining[J]. Journal of China Coal Society，2023，48(10)：3750−3765.