采空区残留煤柱阻流机理与受载水浸灾变机制

采空区残留煤柱是矿井地下水库工程的重要组成部分，但其渗透能力要远低于垮落带破碎煤岩体，造成煤柱附近矿井水积聚，影响地下水库正常运行。另一方面残留煤柱受复杂应力、长期水浸影响，产生“损伤-渗流-累积损伤”效应，严重时将导致煤柱失稳。本项目基于神东矿区典型工程背景，量化表征残留煤柱应力与水环境，揭示各场物理量分布变化规律；构建“孔隙-裂隙”双渗流本构关系，阐明残留煤柱在矿井地下水库蓄放水过程中的阻流机理；采用加载CT从宏细观角度分析受载-水浸-水渗过程中煤体初始损伤-受载损伤-水损伤耦合特征，量化表征应力、水浸时间、水浸高度等因素对残留煤柱损伤的影响程度；探索采空区残留煤柱受载-水浸-水渗多场耦合大尺度模拟实验方法，揭示残留煤柱受载水浸阻流机理与灾变机制；提出基于孔隙分形维数的损伤系数，构建残留煤柱损伤程度与承载渗流能力的量化关系。预期研究成果有助于科学评价煤矿地下水库稳定性和流场演化特征。

Residual coal pillar in goaf is an important part of underground reservoir engineering. Its permeability is much lower than the broken coal and rock mass in the caving zone, which causes the accumulation of mine water near coal pillar and affects the normal operation of the underground reservoir. Besides, the residual coal pillar is affected by complex stress and long-term water immersion, resulting in "damage-seepage-cumulative damage" effect, which will lead to the instability of coal pillar. Based on the typical engineering background of Shendong mining area, this project quantitatively characterizes the residual coal pillar stress and water environment, and reveals the distribution and variation law of physical quantities in each field. The "pore-fracture" dual seepage constitutive relation is constructed to clarify the flow resistance mechanism of residual coal pillar in the process of underground reservoir water storage and discharge. Loading CT was used to analyze the coupling characteristics of initial damage, loading damage and water damage of coal mass in the process of loading-water immersion-water flow from macro and micro perspectives, and quantitatively characterize the influence degree of stress, water immersion time, water immersion height and other factors on the damage of residual coal pillar. The multi field coupling simulation experiment method of loading, water immersion and water flow were developed for residual coal pillar in underground reservoir. It further reveals the mechanism of flow resistance and activation of residual coal pillar under the coupling effect of loading and water immersion. The damage coefficient based on pore fractal dimension is proposed to establish quantitative relationship between damage degree and bearing seepage capacity of residual coal pillar. The research results are expected to be helpful for scientific evaluation of the stability and flow field evolution distribution of coal mine underground reservoir.