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瓦斯涌出衰减特征法测定水力冲孔抽采影响半径

Determination of influence radius of hydraulic punch extraction by gas emission attenuation characteristic method

  • 摘要: 确定水力冲孔瓦斯抽采影响半径参数对于提高瓦斯抽采效率,消除钻孔间防突空白带,保证煤矿安全生具有重要的现实意义。在研究分析钻孔周围煤体松动对瓦斯涌出的影响,负压抽采下排放钻孔瓦斯流动、涌出特点,发现排放钻孔瓦斯涌出可分为前期、后期2个阶段,应用钻孔瓦斯涌出量负幂指数方程分别计算前期瓦斯排放量和后期瓦斯极限排放量,两者加和为钻孔瓦斯极限排放量Qj,提高了计算求解的准确性;指出负压抽采影响下排放钻孔周围煤体瓦斯流向抽采钻孔,是排放孔后期瓦斯涌出衰减系数突变性减少原因,造成排放孔百米钻孔瓦斯极限排放量与未受抽采影响的显著差异性;根据受负压抽采影响出现的排放钻孔瓦斯涌出衰减系数突变性、排放钻孔百米瓦斯极限排放量显著差异特征,提出了瓦斯涌出衰减系数特征法测定水力冲孔抽采影响半径的方法;运用此法在鹤壁中泰煤业公司进行了现场测试,结果表明,煤孔平均冲出煤量1.3 t/m,抽采时间60 d,抽采影响半径为5.1 m。

     

    Abstract: It is of great practical significance to determine the influence radius parameters of gas drainage by hydraulic punching through strata for improving the gas drainage efficiency, eliminating the gap between the drilling holes and ensuring the safety of coal mines. This paper studied and analyzed the influence of coal loose around the borehole on gas emission, and the characteristics of gas flow and emission from the borehole under negative pressure extraction. The negative power exponential equation of borehole gas emission calculates the gas emission in the early stage and the limit gas emission in the later stage respectively, and the sum of the two improves the accuracy of calculation and solution for the limit gas emission in the borehole; It is pointed out that the flow direction of coal gas around the drainage hole under the influence of negative pressure extraction is the reason for the sudden reduction of gas emission attenuation coefficient at the later stage of the drainage hole, resulting in a significant difference between the gas emission limit of 100-meter borehole of the drainage hole under the influence of negative pressure extraction and the one that has not been affected by the drainage; According to the abrupt change of gas gushing attenuation coefficient of discharge boreholes affected by negative pressure drainage and the significant difference of gas discharge limit of 100 meters of discharge boreholes, a characteristic method of gas gushing attenuation coefficient is proposed to determine the influence radius of hydraulic punching drainage. Using this method, the field test was carried out in Hebi Zhongtai Coal Industry. The results show that the average amount of coal flushed out of the coal hole is 1.3 t/m, the extraction time is 60 days, and the extraction influence radius is 5.1 m.

     

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