## 3 Test Results
### Anisotropic Variation  
According to Formula (1), proposed by [PERSON] et al. (2019), the anisotropy indexes of rock physical and mechanical properties are obtained. \[R_{S}=\frac{(S_{max}-S_{min})}{S_{mean}}\times 100\% \tag{1}\]  
Figure 12: Temperature-dependent variation in the internal friction angle of granite in different sampling directions. Figure 13: The variation law of granite cohesion with different temperatures in different sampling directions. \(R_{S}\) is the anisotropy of a certain physical and mechanical index of granite, \(S_{max}\) is the maximum value of this index, \(S_{min}\) is the minimum value of this index, and \(S_{mean}\) is the average physical and mechanical index of rock samples in all sampling directions. Figure 14 illustrates the variation of the granite wave velocity anisotropy with different temperatures. At a heating temperature of 200 \({}^{\circ}\)C, the granite's anisotropy decreased. This decrease in wave velocity was attributed to the removal of free water and weakly bound water from primary fractures within the granite. On the other hand, an increase in the temperature led to the expansion and mutual compression of mineral particles, which could cause some cracks to be compressed or even disappear. This phenomenon was random and irregular, resulting in a decrease in the anisotropy of the granite wave velocity at 200 \({}^{\circ}\)C. As the heating temperature increased, the anisotropy of the two types of rocks gradually increased. New microcracks were generated and propagated along the weakest surface of the mineral crystals and might have also connected to form large cracks. At 400 \({}^{\circ}\)C, the anisotropy of the granite wave velocity increased. At 600 \({}^{\circ}\)C, the anisotropy of the longitudinal wave velocity in the granite reached its maximum value, which was significantly greater than that at room temperature. After heating above 800 \({}^{\circ}\)C, the anisotropy of the longitudinal wave velocity in the granite decreased but was still greater than that in the normal temperature state. It can be inferred that temperatures above 400 \({}^{\circ}\)C can amplify the anisotropy of the longitudinal wave velocity in granite. The trend of the peak deviatoric stress anisotropy with respect to temperature under different confining pressure conditions is shown in Figure 15. Under uniaxial compression conditions, the peak deviatoric stress anisotropy first increased and then decreased with temperature. In the temperature range of 200-600 \({}^{\circ}\)C, the anisotropy of the peak deviatoric stress increased compared to that at room temperature, indicating that within this temperature range, thermal damage within the granite leads to a more pronounced anisotropy of the peak stress in the granite. When the heating temperature exceeded 600 \({}^{\circ}\)C, the anisotropy of the peak deviatoric stress in the granite rapidly deteriorated, and the difference in the peak deviatoric stress in each sampling direction decreased. As the confining pressure increased, it could be observed that the confining pressure can significantly reduce the anisotropy of the granite peak deviatoric stress. At various temperature levels, the anisotropy of the granite did not change much compared to that at room temperature, indicating that under the combined influence of a confining pressure and temperature, the peak deviatoric stress of granite can still show a certain degree of anisotropy. Figure 14: The variation law of wave velocity anisotropy with different temperatures. Figure 16 shows the variation in the anisotropy of the elastic modulus with different temperatures. Under various confining pressure conditions, the anisotropy of the granite elastic modulus remained basically unchanged with different temperatures, and the anisotropy of the elastic modulus first increased and then decreased with an increasing temperature. The degree of anisotropy reached its maximum value at 400 \({}^{\circ}\)C, and as the temperature continued to rise, the degree of anisotropy began to decrease.