为研究采动影响下构造发育区煤层瓦斯运移规律,以桑北矿区为工程背景,综合运用理论分析、现场实测与数值模拟的方法,通过构建采动影响下煤体渗透率动态演化模型,结合煤岩应力场、变形场和渗流场相互作用,研究了瓦斯运移流固耦合机制。研究发现,桑北整合区位于鄂尔多斯盆地伊陕斜坡东南,构造复杂,含褶曲、断层等,地应力受重力与构造运动双重影响,3#煤层应力值普遍小于15MPa。基于含瓦斯煤层应力-损伤-渗流多场耦合模型建立数值模拟,模拟不同抽采时间下瓦斯运移情况。结果表明:原始区域抽采时瓦斯压力变化区域随时间外扩,30d变化明显,180d后幅度变小;完全卸压区域瓦斯压力随时间降低,卸压程度越高受抽采钻孔影响越明显,降低幅度越大;构造发育区瓦斯压力变化受构造发育程度影响,发育程度越高影响越小,且随抽采时间增加压力变化区域扩大,前90d变化明显。现场实测与模拟结果对比显示,原始区域、完全卸压区域和构造发育区瓦斯压力变化趋势分别基本一致。

In order to study the law of coal seam gas migration under the influence of mining, the method of theoretical analysis, field measurement and numerical simulation is carried out based on the engineering background of Sangbei Mining area. By building a dynamic evolution model of coal permeability under the influence of mining and combining the interaction of coal-rock stress field, deformation field and seepage field, the fluid-solid coupling mechanism of gas migration is analyzed. It is found that the Sangbei integration area is located in the southeast of Yishan Slope in Ordos Basin. It has complex structures, including folds and faults, and the ground stress is influenced by gravity and tectonic movement. The stress value of the coal           seam is generally less than MPa. Based on the multi-field coupling model of stress-damage-seepage in gas-bearing coal seams, numerical simulation was established to simulate the gas migration under different extraction times. The results show that the variation area of gas pressure in the original extraction area expands with time, the change is obvious at days, and the amplitude decreases after days. The gas pressure in the complete pressure relief area decreases with time, and the higher the pressure relief degree is, the more obvious the influence of extraction drilling is. The change of gas pressure in the structural development area is affected by the degree of structural development, and the higher the degree of development, the smaller the effect. The change area of pressure expands with the increase of extraction time, and the change is obvious in the first days. The comparison between the field measurement and the simulation results shows that the variation trend of gas pressure in the original area, the complete pressure relief area and the structural development area is basically the same.