外错高抽巷高位钻孔卸压瓦斯抽采技术

Pressure-relief gas drainage technique by high level borehole in lateral high drainage roadway

为解决相邻两工作面上隅角瓦斯超限难题和实现高抽巷＂一巷两用＂,提出外错高抽巷布置方式：沿上工作面回风顺槽侧,在煤层顶板内外错布置走向高抽巷;在高抽巷服务前期,在其内采用高位钻孔抽采上工作面采动卸压瓦斯;在高抽巷服务后期,直接采用高抽巷抽采下工作面采动卸压瓦斯;实现1条高抽巷服务于相邻两工作面,提高高抽巷利用效率。基于山西霍州煤田集团李雅庄煤矿2-603工作面地质条件,建立外错高抽巷围岩结构力学模型,采用理论分析、数值模拟、相似材料模拟及现场实测等研究方法系统分析工作面覆岩采动裂隙发育特征,研究覆岩采动裂隙分布规律,确定外错高抽巷和高位抽采钻孔布置参数;基于高位钻孔测斜结果,提出角度补偿纠偏方法及纠偏效果评价指标。高抽巷位于2煤层顶板25.0 m处,外错2-603工作面25.0 m;高位钻孔终孔位于顶板44.0 m处,水平及倾斜方向上的纠偏角分别为-3°和-2°。研究结果表明：高抽巷受2-603工作面采动影响较小,巷道断面能满足下区段2-605工作面抽采要求;高位钻孔终孔位置合理,高位钻孔抽采瓦斯体积分数高,且持续抽采时间长;采用角度补偿纠偏方法后钻孔瓦斯体积分数的最大值和平均值较纠偏前分别提高15.3%和11.6%,2-603工作面生产班、检修班上隅角瓦斯体积分数分别为0.504%~0.951%和0.467%~0.893%,解决了工作面隅角瓦斯超限难题,保障了工作面安全高效开采。

To solve the problems of the gas consistence exceeding limit at the upper corner of the two adjacent coalfaces and to realize the high drainage roadway with two utilizations, the arrangement mode and the connotation of the lateral high drainage roadway（LHDR） were proposed. Along the air return way of the upper coalface, strike high-bleeding roadway in roof was laid on lateral upper coalface, pressure relief gas in fractured zone of the upper coalface’s overlying strata was extracted by boreholes in high drainage roadway at the earlier stage of service, pressure relief gas in fractured zone of the next coalface’s overlying strata was extracted by the roadway at the later stage of service, the LHDR could serve two coalfaces, and the utilization ratio of the LHDR was improved. Based on the geological conditions of No.2-603 coalface of Liyazhuang coal mine in Huozhou, Shanxi Province, mechanical model of the LHDR was established. Theoverlying strata’s mining-induced fracture development features were analyzed by the methods of the theoretical analysis, numerical simulation, similar material simulation and field measurement, the overlying strata’s mining-induced fracture distribution law was obtained, and the layout parameters of the LHDR and drainage boreholes were determined. Based on the borehole inclination survey results, borehole angle compensation correction method and the evaluation index of borehole correction effect were proposed. The high drainage roadway was located at 25.0 m to the roof of No.2 coal seam, and 25.0 m to the No.2-603 coalface. The borehole’s final hole location was 44.0 m in height over the roof, and the correction angles of the horizontal direction and inclined direction were-3° and-2° respectively. The results show that, mining of the No.2-603 coalface has little influence on the lateral high drainage gateway, the roadway section can meet the drainage requirements of No.2-605 coalface, the borehole’s final hole location is reasonable, and the maximum and average value of the gas concentration is improved by 15.3% and 11.6%, and the gas consistence at the upper corner is 0.504%-0.953% and 0.467%-0.893%.The problem of the gas consistence exceeding limit is solved, and the coalface is mined safely and effectively.