Developing and utilizing mining water resources in ecologically fragile mining areas in western China require underground reservoir technologies. However, the creep and permeability of coal pillar dams under the coupling of overburden pressure and stock water seepage are not well understood. This hinders the control of their long-term stability. This study aimed to reveal these features by examining the creep characteristics and permeability evolution of coal samples under varying osmotic pressures. The results indicate that coal samples under a high osmotic pressure experienced lower creep damage stress but more severe rheological phenomena and damage degree. The permeability of the coal samples exhibited a dynamic variation pattern: the maximum permeability increased with the axial stress and osmotic pressure. Based on rock damage theory and test results, we determined the elastic and viscous damage quantities of the coal samples. After introducing these quantities into our model, we established a fractional-order nonlinear viscoelastic-plastic seepage-creep model that considers the seepage damage throughout the process. The validation results show that the model can accurately characterize the creep process of a coal column dam under seepage-creep coupling. These conclusions provide a scientific guide for related studies and address the problem of blindly controlling the long-term stability of coal pillar dams in underground coal mine reservoirs.

中文翻译：

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渗流与蠕变耦合作用下煤样渗透应变特征及损伤本构模型

西部生态脆弱矿区矿区水资源的开发利用需要地下水库技术。然而，上覆压力与蓄水渗流耦合作用下煤柱坝的蠕变和渗透性尚不清楚。这阻碍了对其长期稳定性的控制。本研究旨在通过检查不同渗透压下煤样的蠕变特性和渗透率演变来揭示这些特征。结果表明，高渗透压下煤样的蠕变损伤应力较低，但流变现象和损伤程度较严重。煤样的渗透率呈现出动态变化规律：最大渗透率随着轴向应力和渗透压的增加而增加。根据岩石损伤理论和试验结果，确定了煤样的弹性损伤量和粘性损伤量。将这些量引入模型后，我们建立了分数阶非线性粘弹塑性渗流蠕变模型，该模型考虑了整个过程的渗流损伤。验证结果表明，该模型能够准确表征渗流-蠕变耦合下煤柱坝的蠕变过程。这些结论为相关研究提供了科学指导，解决了盲目控制煤矿井下水库煤柱坝长期稳定性的问题。