近距离煤层群下行开采底板应力分布与瓦斯抽采技术研究
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摘要
针对沙曲煤矿近距离突出危险煤层群开采的瓦斯防治难题,采用室内试验、数值模拟现场试验等研究手段对近距离煤层群下行开采底板应力分布特征与卸压范围及钻孔瓦斯抽采布置有进行分析。结果表明:煤层群各顶底板岩层物理、力学性质呈现不均匀分布,表现为岩层间横向性质相近,垂向岩性差异性较大的典型层状分布。其中,3号、4号、5号煤层间顶底板均为密度较大、内聚力较大、抗拉、抗压强度均较高的砂岩。4号煤层开采后采空区中部底板岩层一定范围内出现明显的垂直应力为0MPa的区域,底抽巷处在卸压区范围内,采空区中部下方底抽巷围岩垂直应力低于5MPa。底抽巷布置在距5号煤层14m处是合适的。工程实践表明,抽采半年后瓦斯压力由1. 5MPa降至0. 2MPa,平均抽采率维持在80%以上,采用底抽巷抽采瓦斯效果较佳。
Aiming at the gas prevention and control difficulty in the mining of close-range coal seams in Shaqu Coal Mine,the stress distribution characteristics,pressure relief range and drilling gas drainage arrangement of the floor in the downward mining of close-range coal seams are analyzed by means of laboratory test and numerical simulation field test. The results show that: The physical and mechanical properties of the roof and floor strata of coal seam group are uneven distribution,which shows that the horizontal properties of the strata are similar,and the vertical lithologic differences are large. Among them,the roof and floor of No. 3,No. 4 and No. 5 coal seams are sandstones with high density,cohesion,tensile and compressive strength. After the No. 4 coal seam is mined,the obvious vertical stress of the middle floor strata in the goaf is 0 MPa in a certain range,the high floor extraction roadway is within the pressure relief zone,and the vertical stress of the surrounding rock of the bottom extraction roadway in the middle and lower part of the goaf is less than 5 MPa. It is suitable to arrange the floor high extraction roadway at 14 m away from No. 5 coal bed. Engineering practice shows that after half a year of gas extraction,the gas pressure dropped from 1. 5 MPa to 0. 2 MPa,and the daily gas extraction rate maintained above 80%. The bottom drainage roadway has better gas extraction effect.
Aiming at the gas prevention and control difficulty in the mining of close-range coal seams in Shaqu Coal Mine,the stress distribution characteristics,pressure relief range and drilling gas drainage arrangement of the floor in the downward mining of close-range coal seams are analyzed by means of laboratory test and numerical simulation field test. The results show that: The physical and mechanical properties of the roof and floor strata of coal seam group are uneven distribution,which shows that the horizontal properties of the strata are similar,and the vertical lithologic differences are large. Among them,the roof and floor of No. 3,No. 4 and No. 5 coal seams are sandstones with high density,cohesion,tensile and compressive strength. After the No. 4 coal seam is mined,the obvious vertical stress of the middle floor strata in the goaf is 0 MPa in a certain range,the high floor extraction roadway is within the pressure relief zone,and the vertical stress of the surrounding rock of the bottom extraction roadway in the middle and lower part of the goaf is less than 5 MPa. It is suitable to arrange the floor high extraction roadway at 14 m away from No. 5 coal bed. Engineering practice shows that after half a year of gas extraction,the gas pressure dropped from 1. 5 MPa to 0. 2 MPa,and the daily gas extraction rate maintained above 80%. The bottom drainage roadway has better gas extraction effect.
引文
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[4]李日富,梁运培,张军.地面钻孔抽采采空区瓦斯效率影响因素[J].煤炭学报,2009,34(7):942-946.
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[6]谢和平,周宏伟,薛东杰,等.我国煤与瓦斯共采理论、技术与工程[J].煤炭学报,2014,39(8):1391-1397.
[7]卢平,袁亮,陈烨,等.低透气性煤层群高瓦斯采煤工作面强化抽采卸压瓦斯机理及试验[J].煤炭学报,2010,35(4):580-585.
[8]程志恒.近距离煤层群保护层开采裂隙演化及渗流特征研究[D].北京:中国矿业大学(北京),2015.
[9]张春雷.煤层群上行开采层间裂隙演化及卸压空间效应[D].北京:中国矿业大学(北京),2017.
[10]姚晓旭.近距离煤层群首采上位被保护层工作面瓦斯运移规律及治理研究[M].湘潭:湖南科技大学,2017.
[11]石琨.近距离煤层群上保护层煤与瓦斯共采技术研究[J].煤炭工程,2018,50(7):64-66.
[12]陈云.吕梁矿区近距离煤层群下邻近层瓦斯抽采方法研究[J].煤炭工程,2018,50(6):78-80,84.
[13]谢和平,高峰,周宏伟,等.煤与瓦斯共采中煤层增透率理论与模型研究[J]煤炭学报,2013,38(7):1101-1108.
[14]薛俊华.近距离高瓦斯煤层群大采高首采层煤与瓦斯共采[J].煤炭学报,2012,37(10):1682-1687.
[15]刘建高,谢小平,刘宗柱.高瓦斯煤层群薄煤层保护层开采卸压效果分析[J].煤矿安全,2013,33(10):192-195.