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为研究钻孔瓦斯抽采过程中瓦斯运移机制,基于瓦斯渗流扩散方程,探讨钻孔周围不同区域煤体变形和渗透率动态变化,推导出钻孔周围卸压区和非卸压区瓦斯流动耦合方程。根据某矿己15-31010工作面煤体物性参数建立几何模型,利用COMSOL Multiphysics有限元分析软件对耦合方程进行数值求解。结合模拟结果分析煤体形变、渗透率动态变化、钻孔周围瓦斯压力之间的耦合关系。对相关参数模拟结果进行现场抽采效果验证。结果表明,在瓦斯抽采过程中,煤体瓦斯压力随着时间推移逐渐降低,沿钻孔中心向四周方向,瓦斯压力在卸压区迅速增加,在非卸压区增速逐渐变缓,最终趋于稳定;煤体渗透率在钻孔周围呈现非对称V字型变化规律;卸压区的煤体变形较大,变形量在远离钻孔的方向上逐渐减小;模拟结果与现场抽采效果基本吻合。
In order to study the mechanism of gas migration during gas drainage in boreholes, based on the gas seepage diffusion equation, the dynamic changes of coal deformation and permeability in different regions around the borehole are discussed, and the gas flow in the pressure-relief zone and non-relief zone around the borehole is deduced Coupling equation. The geometrical model was established according to the coal body physical parameters of 15-31010 working face in a mine and the coupling equations were numerically solved by COMSOL Multiphysics finite element analysis software. Combining with the simulation results, the coupling relationship between coal deformation, dynamic change of permeability and gas pressure around the borehole is analyzed. Simulation results of the relevant parameters on-site pumping effect verification. The results show that during the process of gas drainage, the gas pressure of coal decreases gradually with the passage of time. The gas pressure increases rapidly in the pressure relief zone and decreases slowly in the non-pressure relief zone, The permeability of coal appears asymmetric V-shaped variation around the borehole; the deformation of coal in the pressure relief area is larger and the deformation decreases gradually in the direction away from the borehole; the simulation results are in agreement with the field extraction The effect is basically consistent.