底抽巷穿层钻孔封孔深度与布孔间距优化研究
Study on optimization of strata passing borehole sealing depth and borehole layout space in floor gas drainage gateway
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摘要: 为了研究抽采钻孔间距、封孔深度、抽采时间对抽采瓦斯浓度的影响,以沙曲矿高瓦斯突出煤层群为研究对象,基于钻场围岩破碎区及其应力集中区现场开展了不同封孔深度的瓦斯抽采对比试验,应用COMSOL数值软件分析了抽采时间及布孔间距对瓦斯抽采效果的影响,提出了合理的穿层钻孔封孔深度和布孔间距。结果表明:随封孔深度增加,瓦斯抽采浓度先逐渐增大后趋于稳定,且存在临界封孔深度;随抽采时间延长,相邻钻孔间瓦斯压力降低呈叠加效应,抽采一定时间后趋于稳定;确定了沙曲矿4号煤层穿层钻孔封孔深度及布孔间距均为10 m;实测得出单孔平均抽采流量随时间延长呈负指数衰减,一年抽采期后有效消除了抽采区域的突出危险性。Abstract: In order to study the gas drainage borehole spacing, borehole sealing depth and gas drainage time importantly affected to the gas drainage concentratio n, taking the high gas outburst seam group in Shaqu Mine as the object, based on the broken zone of the surrounding rock along the drilling site and the site of the stre ss concentrated zone, comparison experiments were conducted on the gas drainage with different borehole sealing depth, the COMSOL numerical software was applied to analyze the gas drainage time and the borehole layout spacing affected to the gas drainage effect and to provide the rational hole sealing depth and borehole layout spacing of the strata passing boreholes. The results showed that with the borehole sealing depth increased, the gas drainage concentration would be firstly steadily incr eased and then would be in stable and there was a critical sealing depth existed.With the gas drainage time extended, the gas pressure reduction between the neighbor ing boreholes would be in a superposition effect and would be in stable after the certain time of the gas drainage.The sealing depth and the borehole layout spacing of t he borehole passed through No.4 seam in Shaqu Mine were 10 m as determined.The average gas drainage flow from a single borehole measured would be in an attenu ation of the negative indexes with the time extended and the outburst danger of the gas drainage area would be effectively eliminated after one year gas drainage.