跨工作面采空区瓦斯抽采技术研究

Research on gas extraction technology in goaf across working face

  • 摘要: Y型通风连续回采工作面采用沿空留巷技术提高煤炭采出率,随着工作面回采,采空区会扩大、连通,回风隅角和挡矸架内风流不畅,瓦斯不仅容易积聚,还很难稀释吹散,导致超限报警频繁。目前针对回风隅角和挡矸架内瓦斯积聚问题的解决方案,无法实现对采空区的持续抽采,且抽采能力较为分散,难以保证治理效果。针对Y型通风连续回采工作面采空区瓦斯治理难题,以东峰煤矿3202工作面为工程背景,提出一种跨工作面采空区瓦斯抽采技术。在相邻工作面的回风巷内施工定向长钻孔至采空区顶板断裂带,定向长钻孔抽采管路在工作面回采后无需撤管,可持续抽采采空区瓦斯,最大限度降低采空区及其顶板断裂带瓦斯存量,形成跨工作面,对采空区瓦斯进行抽采,减少了相邻采空区积聚瓦斯,有效防止顶板大面积垮落时采空区瓦斯突然扇出带来的瓦斯灾害。试验结果表明:跨工作面钻孔距离巷道顶板30~40 m,跨工作面定向长钻孔终孔位置在水平方向上距轨道巷20~40 m时抽采效果理想;施工定向长钻孔至采空区顶板断裂带,持续抽采采空区瓦斯,挡矸架内的瓦斯体积分数由0.67%降至0.22%,回风流瓦斯体积分数由0.47%降至0.18%,回采期间3202工作面瓦斯体积分数保持在0.6%以下。跨工作面采空区瓦斯抽采技术为采空区的瓦斯抽采方式提供了新思路。

     

    Abstract: The Y-shaped ventilation continuous working face adopts the technology of gob-side entry retaining to improve the coal recovery rate. As the working face recovers, the goaf area will expand and connect. The air flow in the return corner and gangue rack is not smooth. Gas not only accumulates easily, but is also difficult to dilute and blow away. This leads to frequent exceeding limit alarms. At present, solutions of the gas accumulation in the return corner and gangue rack is unable to achieve continuous extraction of goaf. The extraction capacity is relatively scattered, making it difficult to ensure the effectiveness of governance. In order to solve the difficult problem of gas control in the goaf of the Y-shaped ventilation continuous working face, a gas extraction technology in cross working face is proposed based on the engineering background of the 3202 working face of Dongfeng Coal Mine. The directional long boreholes are constructed in the return air roadway of adjacent working faces to the roof crack zone of the goaf. The directional long borehole extraction pipeline does not need to be removed after the mining of the working face. The pipeline can continuously extract gas from the goaf, minimizing the gas storage in the goaf and its roof crack zone, forming a cross working face for gas extraction in the goaf. This reduces the accumulation of gas in adjacent goaf areas, and effectively prevents gas disasters caused by sudden gas gushing out of goaf during large-scale roof collapse. The test results show that the distance between the cross working face drilling and the roadway roof is 30-40 meters. The extraction effect is ideal when the final position of the directional long borehole across the working face is 20 to 40 meters horizontally from the track roadway. The directional long boreholes are carried out to the roof crack zone of the goaf, and the gas in the goaf is continuously extracted. The gas volume fraction in the gangue rack decreases from 0.67% to 0.22%. The gas volume fraction in the return air flow decreases from 0.47% to 0.18%. During the mining period, the gas volume fraction in the 3202 working face remaines below 0.6%. The gas extraction technology in the goaf cross working face provides a new approach for gas extraction methods in goaf areas.

     

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