【摘要】 为提高深部煤层瓦斯抽采效率,研究抽采钻孔周围煤体的瓦斯渗流规律十分关键。文中基于煤体的各向异性和非均质性,考虑煤体应力变形场和瓦斯渗流场的交叉耦合作用,分析了煤层抽采中水力割缝钻孔周围瓦斯压力以及渗透率的时空演化规律。结果表明:煤体的各向异性和非均质性影响割缝钻孔周围的瓦斯渗流规律。对于瓦斯压力的变化,平行层理方向瓦斯压力降幅大于垂直层理方向,抽采影响范围分布呈现"椭圆形",煤体各向异性表征明显。对于渗透率的变化,平行层理方向的煤层渗透率高于垂直层理方向,抽采初期渗透率的增加幅度较快,随后逐渐减缓,渗透率变化曲线呈现不规则"锯齿形",煤体非均质性表征明显。将数值模拟结果与杨柳矿4~#钻场瓦斯抽采的实际监测情况相互对比,现场实测的瓦斯抽采情况与模拟得到情况基本吻合,从而验证了数值模拟的合理性及工程适用性。更多还原

【Abstract】 In order to improve gas drainage efficiency of deep coal seams,it is very important to study the gas seepage law of coal bodies around the extraction borehole.Based on the anisotropy and heterogeneity of coal body,considering the cross-coupling effect of coal stress-deformation field and gas seepage field,the space-time evolution law of gas pressure and permeability around the borehole in the extraction process was analyzed.The results show that the anisotropy and heterogeneity of the coal affect the gas flow law around the borehole.For the change of gas pressure,the gas pressure decrease in the parallel bedding direction is larger than that in the vertical bedding direction,and the distribution of the influence range of the extraction is "elliptic",and the anisotropy of the coal body is obviously characterized.For the change of permeability,the permeability of coal seam in parallel bedding direction is higher than that of vertical bedding.The increase of permeability in the initial stage of extraction is faster,and then gradually slows down.The curve of permeability shows irregular "zigzag" and coal body heterogeneity is clearly characterized.The numerical simulation results were compared with the actual monitoring situation of the gas drainage in the 4~# drilling site of Yangliu Mine.The actual gas extraction in the field is basically consistent with the simulated situation,which verifies the rationality of the numerical simulation and the applicability of the engineering practice.更多还原