Sand-based cemented backfill (SBCB) mining technology is instrumental in utilizing coal resources buried under the water bodies. SBCB is exposed to the long-term action of mining-induced stresses in the goaf and groundwater permeating via microcracks along the rock strata. Studying the permeability evolution of SBCB under varying stress states is crucial for protecting coal and water resources below the aquifer. This study is focused on the influence law of different stress states on the SBCB permeability exposed to groundwater, which was tested under different axial and confining pressures using a laboratory seepage meter, particle size analyzer, scanning electron microscope (SEM), and X-ray diffractometer (XRD). Best-fitting quadratic polynomials linking the SBCB permeability with confining and axial pressures, respectively, were obtained via statistical processing of test results. The permeability gradually dropped within the elastic range as the confining and axial pressures increased. Moreover, an increase in the confining pressure caused a more dramatic reduction in the SBCB permeability than the axial pressure. Finally, the SBCB seepage mechanism under different stress states was revealed based on the particle size analysis, XRD patterns, and SEM microstructure. These findings are considered instrumental in substantiating safe mining of coal resources below the water bodies and above the confined groundwater.

中文翻译：

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砂基水泥回填在不同应力条件下的渗透性：围压和轴向压力的影响

沙基水泥回填（SBCB）采矿技术在利用掩埋在水体下的煤炭资源方面发挥了重要作用。SBCB受到采空区长期采矿压力和通过沿岩石地层的微裂缝渗透的地下水的长期作用。研究SBCB在不同应力状态下的渗透性演变对于保护含水层以下的煤炭和水资源至关重要。这项研究的重点是不同应力状态对暴露于地下水的SBCB渗透率的影响规律，并使用实验室的渗漏仪，粒度分析仪，扫描电子显微镜（SEM）和X射线在不同的轴向和极限压力下对其进行了测试。衍射仪（XRD）。最合适的二次多项式，分别将SBCB渗透率与围压和轴向压力联系起来，通过测试结果的统计处理获得。随着围压和轴向压力的增加，渗透率在弹性范围内逐渐下降。此外，围压的增加导致SBCB渗透率的下降比轴向压力更大。最后，通过粒度分析，XRD图谱和SEM显微结构，揭示了不同应力状态下的SBCB渗流机理。这些发现被认为有助于证实水体下方和受限地下水上方的煤炭资源的安全开采。与轴向压力相比，围压的增加导致SBCB渗透率的降低更为明显。最后，通过粒度分析，XRD图谱和SEM显微结构，揭示了不同应力状态下的SBCB渗流机理。这些发现被认为有助于证实水体下方和受限地下水上方的煤炭资源的安全开采。与轴向压力相比，围压的增加导致SBCB渗透率的降低更为明显。最后，通过粒度分析，XRD图谱和SEM显微结构，揭示了不同应力状态下的SBCB渗流机理。这些发现被认为有助于证实水体下方和受限地下水上方的煤炭资源的安全开采。