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采动覆岩卸压瓦斯运储通道属性参数拓扑关系研究

Research on the evolution mechanism of the topological relationship of the property parameters of the mining overburden rock pressure relief gas migration channel

  • 摘要: 煤矿日益加剧的高强度开采过程中,诸多因素综合影响着覆岩裂隙的空间分布特征。覆岩裂隙分布的特征对于解放层开采中的瓦斯治理有着重要的指导意义。通过开展多组二维物理相似模拟试验,探究了不同开采条件下(开采高度、推进速度、关键层层位、煤层倾角)覆岩裂隙网络分布特征及卸压瓦斯运储通道的属性参数,得到了几何参数、裂隙参数的拓扑干系网络。基于复杂网络演化理论可以简化现实干系的拓扑变换,并结合复杂网络特征参数分析运储通道干系结构和因素节点的演化特征,实现了覆岩裂隙网络干系影响因素的定量描述,建立了卸压瓦斯运储通道网络干系结构矩阵及模型。结果表明:卸压瓦斯运储通道的发育范围、贯通度以及分形维数均随着采高、关键层层位及煤层倾角增大而不断扩大;随着推进速度的加快,发育范围却呈现减小的趋势。采高的增加对离层量影响最大,6 m采高相较于4 m时增幅达到146.9%。破断裂隙密度的变化主要受煤层倾角影响,受推速的影响较小,将钻孔布置在高密度区域(破断裂隙密度>4.7条/m),可以有效起到瓦斯截留的作用。研究结果可进一步优化不同因素影响下瓦斯抽采钻孔的布置参数,提高瓦斯抽采效率,从而保证工作面安全高效回采,对实现瓦斯精准绿色抽采具有一定的现实意义。

     

    Abstract: Many factors combine to influence the spatial distribution characteristics of overburden fracture during the increasingly intense mining process in coal mines. The characteristics of overburden fracture distribution has important significance in guiding the gas management in liberated layer mining. Several sets of two-dimensional physical similarity simulation experiments were carried out to investigated the distribution characteristics of overburden fracture network and the property parameters of the pressure relief gas storage and migration channels under different mining conditions (mining height, advancement speed, key layer upon layer and coal seam inclination). The topological network with geometric and fissure parameters was obtained. The topological transformation of the real stem system was simplified based on the theory of complex network evolution, and the evolution characteristics of the stem system structure and factor nodes of the transportation and storage channel was analyzed combined with the complex network characteristic parameters. The influencing factors of the overburden fissure network stem system was quantitatively described, and a matrix and model of the network structure of pressure relief gas transport and storage channel were established. The results indicated that, the development range, through degree, and fractal dimension of pressure relief gas migration and storge channel expand with the increase of mining height, key layer position, and coal seam dip angle. However, the development range shown a decreasing trend with the acceleration of advancing speed. The increase in mining height had the greatest impact on the amount of separation, with a 146.9% increase at 6 m mining height compared to 4 m. The variation in fracture density was mainly influenced by the dip angle of the coal seam, and was less influenced by the advancing speed. Arranging the boreholes in high-density areas (density > 4.7 pieces/m) can effectively act as a gas retention. The research results can further optimize the arrangement parameters of gas extraction boreholes under the influence of different factors, improve the efficiency of gas extraction, so as to ensure the safe and efficient recovery of the working face, which is of certain practical significance for the realization of accurate and green gas extraction.

     

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