Understanding the permeability characteristics of coal under mining disturbance is crucial for ensuring coal mine safety and efficient gas extraction. Coal is a dual porosity medium consisting of matrix and fracture, and there are some differences in mechanics and permeability between matrix pores and fracture. However, research on the damage and gas seepage characteristics of dual-porosity coal is limited. In this paper, a coupled damage-permeability model considering matrix pores and fractures in coal is established, incorporating the influences of effective stress, gas adsorption, thermal expansion, and thermal cracking. And the reliability of the newly developed model was verified using experimental data of temperature and pressure variations under different stress boundary conditions. The results indicate that during the elastic stage, the total permeability and fracture permeability of coal exhibit a trend of decreasing and then increasing with pore pressure, while matrix permeability gradually increases. In the full stress-strain stage, the overall damage-permeability and fracture damage-permeability of coal exhibit an “S"-shaped variation trend with axial strain, while matrix damage-permeability shows a slow increasing trend. To accurately characterize the evolution of gas seepage in coal, contributions from matrix pores and fractures must be comprehensively considered, and the effects of gas adsorption, effective stress, thermal cracking, and thermal expansion on permeability cannot be ignored. Furthermore, through parameter sensitivity analysis, it is found that during the elastic stage, coal permeability decreases with an increase in the adsorption sensitivity coefficient and thermal expansion coefficient. In the full stress-strain process, coal permeability increases with an increase in the damage-permeability coefficient. The results of this study are of great significance for predicting the evolution of coal permeability in the working face ahead under mining disturbance.

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热力耦合作用下双孔隙煤损伤-渗透率模型研究

了解开采扰动下煤炭的渗透特性对于确保煤矿安全和高效瓦斯抽采至关重要。煤是由基质和裂缝组成的双重孔隙介质，基质孔隙和裂缝在力学和渗透率方面存在一定差异。然而，对于双孔隙煤的损伤和瓦斯渗流特性的研究还很有限。本文建立了考虑煤基质孔隙和裂隙的损伤-渗透率耦合模型，综合考虑了有效应力、瓦斯吸附、热膨胀和热裂化的影响。并利用不同应力边界条件下温度和压力变化的实验数据验证了新开发模型的可靠性。结果表明，在弹性阶段，煤的总渗透率和裂缝渗透率随孔隙压力的变化呈现先减小后增大的趋势，而基质渗透率逐渐增大。在全应力应变阶段，煤的整体损伤渗透率和裂隙损伤渗透率随轴向应变呈现“S”形变化趋势，而基质损伤渗透率则呈现缓慢增加的趋势。煤中瓦斯渗流必须综合考虑基质孔隙和裂隙的贡献，不能忽视瓦斯吸附、有效应力、热裂、热膨胀对渗透率的影响。此外，通过参数敏感性分析发现，在弹性阶段，煤的渗透率随着吸附敏感系数和热膨胀系数的增加而减小；在全应力应变过程中，煤的渗透率随着损伤渗透系数的增加而增加，本研究结果具有重要意义。预测开采扰动下工作面煤层渗透率的演变。