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低透煤层增透效果的定量描述和评价一直处于盲目状态,使得煤矿瓦斯治理中致裂措施、瓦斯抽采不能因地制宜。增透率可反映采动或人工增透措施对煤岩体渗透特性的改变,并可定量评价煤层增透效果,其分布和演化规律可精准圈定瓦斯富集区域,指导瓦斯抽采钻孔的合理布置。在简化钻孔和裂隙模型基础上,求解了采动条件下钻孔的体积应变,提出了针对单孔的增透率计算方法;依托同煤矿塔山矿8212采面,开展现场裂隙探测试验,研究了工作面前方采动裂隙网络发育演化及卸压增透变化规律,并分析了单孔增透率随回采面推进的演化特征。结果表明:裂隙网络呈现“从无到有、从短变长、从窄变宽、不断贯通”的趋势,煤岩体单孔增透率随回采面推进呈现先逐渐上升后保持平稳的趋势,该成果有望直接优化煤矿现场瓦斯抽采孔的布置设计。
The quantitative description and evaluation of the anti-seepage effect of low permeability coal seam has been in a blind state, which makes the cracking measures in coal mine gas treatment and gas drainage can not be adapted to local conditions. The increase of permeability can reflect the change of seepage characteristics of coal and rock mass caused by mining or artificial augmentation measures, and can quantitatively evaluate the anti-seepage effect of coal seam. The distribution and evolution law can precisely define the gas-enriched area and guide the gas drainage Reasonable layout. Based on the simplification of borehole and fracture model, the volumetric strain of borehole under mining condition was solved, and the calculating method of permeability for single hole was put forward. Based on the 8212 face of Tashan Mine in Datong Coal Mine, site crack detection was carried out, The development and evolution of fractured network in front of working face and the law of pressure-relief and penetration enhancement are analyzed. The evolution characteristics of single-hole permeability with the advancing face are analyzed. The results show that the fracture network presents the trend of “from scratch, from short to long, from narrow to broad and continuous”, and the single-hole permeability of coal and rock mass rises steadily with the pushing of the mining face Trend, the result is expected to directly optimize the layout design of coal mine gas drainage holes.