考虑推进速度效应的高位定向钻孔优势布置与效果分析

Superior layout and effect analysis of high directional drilling considering advancing speed effect

为了提高采空区的瓦斯抽采能力,控制工作面的瓦斯涌出,以王家岭矿12302工作面为试验对象,研究了煤层开采后覆岩采动裂隙的演化规律;根据矿井的实际抽采效果研究了不同日推进速度下钻孔层位和平距的定量关系,并对高位钻孔进行了设计和抽采效果考察。结果表明:覆岩的裂隙的发育范围和数量随着工作面的推进逐渐增大增多,多次来压后,采空区覆岩中部形成了明显的压实区,瓦斯富集区在进、回风巷20~50 m,煤层顶板以上25~50 m范围内,覆岩垮落带高度为28.2 m,裂隙带为118.6 m;不同日推进速度下钻孔的优势层位和平距符合一次线性方程关系y=ax±b,依据研究结果设计的高位钻孔实施后,对比孔的抽采纯量低于其余4个钻孔,最大单孔瓦斯抽采纯量较其它钻场的最大单孔瓦斯抽采纯量提高了51%,高位定向钻孔的平均瓦斯抽采率为68%,有效的提高了工作面的瓦斯抽采效果,控制了工作面的瓦斯涌出,抽采期间上隅角和回风流最大瓦斯体积分数均保持在0.8%以下,能够保证矿井的安全生产。

In order to control the gas flow of the working surface, improve the gas extraction capacity of the mining-out area, this paper takes Wangjialing Mine 12302 working surface as a test object, and the evolution law of mining-induced fractures in overburden rock after coal mining is studied. According to the actual pumping effect of the mine, the quantitative relationship of drilling layer and spacing under different daily advancing speed is studied, and the design of high drilling and the pumping effect are investigated. The development range and number of cracks in overburden gradually increased with the advance of working face. After several times of pressure, obvious compaction area was formed in the middle of overburden in goaf. In the gas rich area, the height of overburden caving zone was 28.2 m and the height of fracture zone was 118.6 m within the range of 20-50 m in inlet and return air roadway and 25-50 m above the roof of coal seam. The dominant horizon and spacing of drilling holes at different daily advancing speeds conform to a linear equation y =ax ±b. After the high-position drilling designed according to the research results is implemented, the pure amount of gas extraction from contrast holes is lower than the other four holes, and the maximum pure amount of gas extraction from single hole is 51% higher than that from other drilling fields. The average gas extraction rate of high directional holes is 68%, which effectively improves the effect of gas extraction from working face and controls the gas emission from working face. The maximum gas volume fraction of the upper corner and the return flow is kept below 0.8% during the extraction period, which can ensure the safe production of the mine.