摘要:
杜儿坪煤矿北三盘区8号煤瓦斯含量高，直接顶和基本顶均为坚硬的石灰岩，工作面回采后在上隅角容易形成较大面积悬顶，短期内不易自然垮落，致使相邻工作面保护煤柱内应力集中程度高。在工作面回采过程中，布置在煤柱下方的底抽巷受超前及侧向支承压力的影响，往往发生较大变形，严重影响了巷道通风和瓦斯抽采。受强烈动压影响的底抽巷，矿压显现剧烈，不能满足一巷两用需求。针对上述问题，以68306工作面为研究对象，开展了水力压裂切顶卸压护巷（底抽巷）技术研究。在回风巷靠煤柱侧不采帮顶板上实施水力压裂切顶卸压护巷技术，切断巷道和煤柱上方基本顶的连接，减小侧向悬臂梁的长度，削弱或转移煤柱上覆的高应力，降低煤柱的载荷，使68306底抽巷处于低应力区域，从根本上改变巷道围岩的应力状态，达到卸压护巷的效果。试验结果表明，实施水力压裂切顶卸压护巷技术后，明显降低了底抽巷围岩变形量，两帮和顶底板变形量分别控制在12%和20%以内；回风巷实施水力切顶后，工作面上隅角悬顶面积得到了有效控制，避免了上隅角瓦斯积聚。
Abstract:
The gas concentration of No.8 coal seam in north 3 panel of Duerping Coal Mine is high, the direct roof and the basic roof are both hard limestone, and it is easy to form a large area of hanging roof in the upper corner after stoping on working face, which is not easy to collapse naturally in a short time, resulting in a high degree of stress concentration in the protective coal pillar of the adjacent working face. In the process of stoping of working face, floor gas drainage roadway arranged under the coal pillar is often affected by advance and lateral supporting pressure, which often results in large deformation and seriously affects ventilation and gas extraction of the roadway. Under influence of strong dynamic pressure, the floor gas drainage roadway shows intense pressure, which cannot satisfy the dual-use of one roadway. In view of the above problems, taking 68306 working face as research object, application research on roadway protection (floor gas drainage roadway) technology by hydraulic fracturing roof cutting pressure relief was carried out. The roadway protection technology by hydraulic fracturing roof cutting pressure relief was adopted on roof near the coal pillar side in air return way to cut off the connection between the roadway and the basic roof above the coal pillar, and minimize the length of side cantilever beam, weaken or transfer high stress of overlying coal pillar, reduce the load of coal pillar,so as to make 68306 floor gas drainage roadway be in a low stress area, fundamentally change the stress state of roadway surrounding rock,which achieves the effect of pressure relief and protect the roadway. The test results show that the deformation of surrounding rock of floor gas drainage roadway is obviously reduced after implementation of roadway protection technology by hydraulic fracturing roof cutting pressure relief, the deformation of the two sides and the roof and floor are controlled within 12% and 20% respectively. After using hydraulic fracturing roof cutting in air return way, the area of hanging roof in the upper corner of the working face is effectively controlled, and the gas accumulation in the upper corner is avoided.
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