The microstructure and appearance of sandstone samples from the bank slope of the Three Gorges Reservoir of the Yangtze River in Wanzhou District, Chongqing, China, were evaluated before and after wetting/drying cycles in aqueous solution using nuclear magnetic resonance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Water/rock interactions including dissolution, ion exchange, hydration, dissolution, and oxidation/reduction changed the mineral composition and microstructure of the rock mass media along with the pore structure and mineral particle shape of the rock mass. During wetting/drying cycles, the internal morphology of the sandstone gradually changed from neat and dense to fractured and loose. In greenish-grey sandstone, multiple wetting/drying cycles led to decreases in the proportions of micropores (0–0.01 μm) and small pores (0.01–0.1 μm), while the proportions of mesopores (0.1–1 μm) and macropores (> 1 μm) gradually increased. In gray-white sandstone, multiple wetting/drying cycles also lead to a decrease in the proportion of micropores, while the proportions of small pores, mesopores, and macropores gradually increased. These results could provide a significant guidance for the further study of the stability of the slope rock on the reservoir bank and the formation of effective stability maintenance and reinforcement measures.

中文翻译：

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干湿循环对万州砂岩孔隙特征的影响

使用核磁共振波谱，扫描电子显微镜，对重庆市万州区长江三峡水库水库边干/湿循环前后的砂岩样品的微观结构和外观进行了评估，和能量色散X射线光谱。水/岩石相互作用包括溶解，离子交换，水合作用，溶解和氧化/还原，改变了岩体介质的矿物组成和微观结构，以及岩体的孔隙结构和矿物颗粒形状。在湿/干循环中，砂岩的内部形态逐渐从纯净致密变为破裂松散。在灰绿色的砂岩中μ M）和小孔（0.01-0.1 μ M），而中孔（比例0.1-1 μ M）和大孔（> 1 μ M）逐渐增加。在灰白色砂岩中，多次润湿/干燥循环也会导致微孔比例的减少，而小孔，中孔和大孔的比例逐渐增加。这些结果可为进一步研究库岸边坡岩体的稳定性以及形成有效的稳定维护与加固措施提供重要的指导。