Understanding the flow behaviors of two-phase fluids in rock mass fractures holds significant importance for the exploitation of oil and gas resources. This paper takes rock fractures with different surface roughness characteristics as its research object and conducts experiments on the gas–water seepage laws of fractures under various confining pressures and shear displacements. The results indicate that the higher the fracture surface roughness, the larger the equivalent fracture width and the higher the single-phase permeability of gas/water in the fractures. During gas–water two-phase flow, when the water phase split flow rate is high, the influence of the confining pressure and fracture surface morphology on the water phase is significantly higher than that on the gas phase. The relative permeability at the isosmotic point of the fractures increases with the increase in confining pressure and decreases with the increase in roughness. After the dislocation of shale fractures, the interphase resistance within the fractures reduces. The relative permeability of the water phase increases more significantly compared to that of the gas phase. The water phase split flow rate at the isosmotic point does not change significantly, and the relative permeability at the isosmotic point increases. This research is helpful for guiding the protection based on the conductivity capacity of the rock mass fracture network.

To simulate the partial immersion exposure typical of underground water storage, concrete specimens of different strength grades were partially submerged in Na₂SO₄ solution. Ultrasonic pulse velocity testing, microhardness measurements, and nanoindentation were employed to evaluate physical and micro-mechanical property degradation. In addition, the phase composition and content changes in different concrete regions using X-ray diffraction and thermogravimetric–differential scanning calorimetry are analysed to detect the time-varying phase compositions of concrete in various regions. The findings indicate that with the progress of corrosion, the overall infiltration of the wet area of C30 concrete tends to stabilize after attaining a certain height along the waterline. Subsequently, the corrosion solution gradually infiltrates and ascends along the concrete surface, leading to the overall breakdown and damage of the concrete within the climbing area from the water level line. In the corrosion and deterioration process of C40 concrete due to sulphate exposure, the corrosion solution gradually ascends from the concrete surface. The degree of surface degradation correlates with the height of the corrosion solution, eventually reaching the top of the concrete. As the sulphate surface climbing height increases, the ongoing alkali consumption reaction between the sulphate and the cement hydration product ultimately causes the fracture and decomposition of the cement stone structure.