下伏邻近层瓦斯采动卸压运移规律及抽采特征研究

Study on Mining Pressure Relief Migration Law and Extraction Characteristics of Underlying Adjacent Layer Gas

为研究下伏邻近层瓦斯采动卸压运移规律及顺层钻孔瓦斯抽采特征,以屯兰矿2^(#)煤层为研究对象,基于下伏采动卸压理论、底板采动破坏深度经验公式和稳定同位素测定分析技术,分析了下伏邻近层瓦斯卸压涌出规律,对下伏煤层顺层瓦斯钻孔采动卸压抽采特征进行了研究。结果表明:12507工作面底板采动破坏深度24.80 m,采动卸压后单孔最高抽采浓度75%、流量0.5 m^(3)/min,下伏邻近层瓦斯抽采量占工作面瓦斯抽采总量的27.08%,为实现下伏卸压瓦斯高效治理,需对下伏4^(#)煤进行采前预抽和采动抽采;根据上隅角瓦斯主要来源及占比,将工作面瓦斯涌出划分为3个阶段,单一煤层主导阶段、邻近层卸压调整阶段及卸压平衡阶段;工作面回采6~100 m时,采空区下伏4^(#)煤迅速卸压,瓦斯大量涌出至采空区,100 m后下伏4^(#)煤层瓦斯达到稳定卸压涌出。

In order to study the law of gas depressurization movement in the adjacent strata and the characteristics of gas extraction in the borehole along the strata,taking the No.2 coal seam of Tunlan mine as the research object,the law of gas depressurization emission in the adjacent strata was analyzed based on the theory of underlying mining depressurization,the empirical formula of floor mining failure depth and the determination and analysis technology of stable isotope.The characteristics of mining and pressure relief extraction of gas borehole along the underlying coal seam are studied.The results show that:The mining failure depth of the floor of 12507 face is 24.80 m,the maximum extraction concentration of a single hole after mining pressure relief is 75%,the flow rate is 0.5 m^(3)/min,and the gas extraction amount of the underlying adjacent layer accounts for 27.08% of the total gas extraction of the working face.In order to achieve efficient gas control of the underlying pressure relief,pre-mining and mining extraction of the underlying No.4 coal should be carried out.According to the main source and proportion of gas in the upper corner,the gas emission of the working face can be divided into three stages:the dominant stage of a single coal seam,the pressure relief adjustment stage of the adjacent layer and the pressure relief balance stage.When the mining face is 6-100 m,the pressure relief of No.4 coal under the goaf is rapid,and a large amount of gas gush to the goaf.After 100 m,the gas of the No.4 coal seam reaches stable pressure relief and gush.