## 1 Introduction
However, the specific effects are variable and depend on the rock type. For sedimentary rocks, such as siltstones and sandstones, water saturation frequently leads to a substantial decrease in the compressive strength, elastic modulus, shear strength, and tensile strength, accompanied by a significant increase in crack development and failure severity. In contrast, metamorphic rocks, such as granites, may exhibit different responses. The impact of water saturation on their strength and deformation parameters is more complex and is influenced by factors such as mineralogical and petrographic composition, particularly the content of clay particles. Using true triaxial loading experiments can effectively replicate the actual stress conditions of rock masses in the complex underground environment found in mines. The impact of water-rock chemical interactions on rock degradation under true triaxial conditions has gained increasing attention. [PERSON] et al. [26] conducted true triaxial experiments on sandstone using different chemical solutions and found that the chemical composition of water significantly influenced the strength and deformation characteristics of rocks. Acidic and alkaline solutions accelerate the transition of rocks from brittle to ductile behavior, significantly degrading their mechanical parameters. Similarly, [PERSON] et al. [27] studied the effect of the moisture content on siltstone and pointed out that an increased moisture content significantly weakened the local cohesion of the rock, leading to a decrease in bearing capacity, with the failure mode exhibiting enhanced plasticity. Through true triaxial experiments, [PERSON] et al. (2018) revealed the failure modes of rocks under multiaxial stress conditions and their mechanical properties under the influence of water. Their study found that the failure modes of red sandstone in the natural and water-saturated states were significantly different. Under water-saturated conditions, the rock exhibited tensile failure, whereas under natural conditions, a combined tensile-shear failure occurred, indicating that the presence of water changed the mode of rock failure. [PERSON] et al. (2019) used true triaxial Hopkinson pressure bar tests to study the dynamic characteristics of coal samples under different pre-stress conditions. They found that static pre-stress under true triaxial conditions significantly increased the dynamic strength of the coal samples and reduced the extent of failure, whereas water infiltration further exacerbated the degradation process. Additionally, true triaxial experiments during the unloading process provide a clearer understanding of the effects of water-rock interactions on the rock energy evolution. [PERSON] et al. (2019) conducted unloading disturbance experiments to study the failure behavior of deep rocks under different stress paths. They found that the rocks exhibited strong dilation in the unloading direction and that the presence of water further exacerbated crack propagation and reduced rock mass stability. [PERSON] et al. (2019) developed a shear deformation band prediction model for sandstone under unloading conditions in true triaxial experiments and revealed the impact of the intermediate principal stress on the rock failure mode. Their study provided a theoretical basis for understanding the failure behavior of rock masses under complex hydrogeological conditions. In studies on the impact of water-rock interactions on rock permeability, [PERSON] et al. (2019) used true triaxial hydraulic fracturing experiments to compare the enhancement of permeability in sandstone roofs and soft coal seams. Their results showed that under hydraulic fracturing, the fracture network in the sandstone developed significantly, leading to a noticeable increase in permeability, whereas the coal seam exhibited compaction and fracture closure, indicating that water infiltration not only affected the mechanical properties of the rocks but also directly influenced the fracture propagation and permeability.