## 3 Experimental Results and Analysis
### Mechanical Properties of Argillaceous Silitstone Under Different Water Temperatures
To understand the failure characteristics of argillaceous siltstone in different water temperature solutions, a failure characteristic analysis was conducted on the specimens after failure. As shown in Figure 6, argillaceous siltstone subjected to different water temperatures under uniaxial compression produced more than one obvious failure crack, and the failure surfaces were rough. At water temperatures of 5 \({}^{\circ}\)C and 35 \({}^{\circ}\)C, the failure mode of argillaceous siltstone was mainly tensile failure, with tensile cracks generated under axial stress that did not penetrate the entire specimen, maintaining a relatively intact state. At water temperatures of 15 \({}^{\circ}\)C and 25 \({}^{\circ}\)C, the failure mode was primarily \"X\"-shaped shear failure, with a significant increase in the number of tensile cracks accompanied by the appearance of shear cracks. The tensile cracks initiated and propagated from the crack tips, extending linearly towards both ends of the rock specimen. Eventually, the cracks interconnected, causing severe local damage or even spalling of the rock mass, resulting in a relatively fragmented state of the specimen. Figure 6: Failure modes of argillaceous siltstone under different water temperatures: (**a**) 5 \({}^{\circ}\)C. (**b**) 15 \({}^{\circ}\)C. (**c**) 25 \({}^{\circ}\)C. (**d**) 35 \({}^{\circ}\)C.  
In the analysis of rock microstructures, scanning electron microscopy (SEM) plays a crucial role. SEM can reveal the fine structural characteristics of rocks, thereby aiding in the understanding of their mechanical mechanisms. To investigate the microstructural characteristics of argillaceous siltstone under different water temperatures, a field emission scanning electron microscope was used for an in-depth study. The SEM can perform imaging analysis on samples at a magnification of 4000 times. As shown in Figure 7a, after soaking for 3 days, changes in water temperature significantly affect the strength of argillaceous siltstone. Therefore, argillaceous siltstone samples soaked for 3 days under different water temperature conditions were selected for SEM imaging, and the results are shown in Figure 7.  
Figure 5a-d show the microstructures of argillaceous siltstone under water temperatures of 5 \({}^{\circ}\)C, 15 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, and 35 \({}^{\circ}\)C, respectively. At 5 \({}^{\circ}\)C, parts of the quartz structure have been damaged, and a small amount of flocculent bodies and fine particles appear. These flocculent bodies typically manifest as micron- to millimeter-sized aggregates. As the temperature increases to 15 \({}^{\circ}\)C, the degree of damage to the quartz structure further intensifies, forming a large number of flocculent bodies, most of which have been damaged and form corrosion grooves. At 25 \({}^{\circ}\)C, the quartz structure shows signs of fracturing, the number of flocculent bodies decreases, and the corrosion grooves become shallower and narrower. At 35 \({}^{\circ}\)C, the quartz structure is relatively intact, the flocculent bodies significantly decrease, and their structure shows no evident signs of damage. Due to the significant changes in the internal structure of argillaceous siltstone under different water temperatures, the impact of water temperature on the strength and elastic modulus of argillaceous siltstone becomes very pronounced.