## 3 Analysis of Test Results
### Rock Mechanical Properties Under the Interaction of Multiple Factors
#### 3.3.2 Factor Interactions on Peak Stresses
Due to the strong superposition effect of the two factors, the peak stress of the rock specimen is the largest under the conditions of high grouting material strength and high roughness, indicating that for rock masses with high fracture roughness, the selection of high-strength grouting materials can better enhance the bearing capacity and stability of the rock mass; under high levels of confining pressure and grouting material conditions, the peak stress of the rock specimen is the largest, indicating that in high confining pressure environments (such as deep tunnels or mines), high-strength grouting materials should be given priority to fully utilize the gain effect of confining pressure; under conditions of high fracture dip and high roughness, the peak stress of the rock specimen is the largest, indicating that in geological environments with a large fracture dip angle, optimizing the roughness of the fracture surface can effectively increase the peak stress and overall stability of the rock mass. According to Figures 11 and 12, under the interactive effect of grouting material and the number of freeze-thaw cycles, and the number of freeze-thaw cycles and confining pressure, as the interactive factors increase, the peak stress of the rock specimen increases, but the increase is less than the effect of the two factors being superimposed independently (the decrease in peak stress due to the interaction between grouting material and number of freeze-thaw cycles is 86.46%, and the decrease due to the interaction between the number of freeze-thaw cycles and confining pressure is 57.68%). From the density of the contour lines, it is evident that grouting material in the interaction between grouting material and the number of freeze-thaw cycles, and confining pressure in the interaction between confining pressure and number of freeze-thaw cycles, has a more prominent influence on peak stress, respectively. Interaction between grouting material and number of freeze-thaw cycles: During the transition from low to high numbers of freeze-thaw cycles, the peak stress gain decreases from 27.76 MPa to 16.45 MPa, a decrease of 40.7%, as the strength of the grouting material increases. The unfrozen and thawed rock mass has a high initial strength, and the improvement in the strength of the grouting material can significantly enhance the rock mass's resistance to freeze-thaw damage. However, at a high number of freeze-thaw cycles, the  
Figure 11: Visualization of the interaction effect between grouting material and the number of freeze–thaw cycles on peak stress. rock mass will experience crack expansion and strength degradation due to repeated freezing and thawing, and even if the strength of the grouting material is improved, its effect on increasing the peak stress is limited. In addition, under the condition of low-strength grouting material, the increase in the number of freeze-thaw cycles resulted in a 55.2% decrease in peak stress, while under high-strength grouting material, the increase in the number of freeze-thaw cycles resulted in a 47.7% decrease in peak stress. The low-strength grouting material has a limited reinforcing effect on the crack surface, and the cumulative effect of freeze-thaw cycles is more likely to cause a decrease in peak stress. High-strength grouting material, on the other hand, can effectively slow down freeze-thaw damage, thereby maintaining a higher peak stress. Interaction between number of freeze-thaw cycles and confining pressure: As the number of freeze-thaw cycles changes from low to high, the peak stress gain decreases from 33.89 MPa to 23.75 MPa with increasing confining pressure, a decrease of 29.9%. The unfrozen rock mass has a relatively complete structure, and the confining pressure helps to compact the original microcracks and micropores, thereby improving the strength of the rock mass.