## 3 Results and Discussion
### Temperature Difference Between the Left and Right Sides of the Fracture  
Figure 9 reveals the temperature variations of the horizontal monitoring line F-F in fractured granite during the entire heating process with a heat source of 80 \({}^{\circ}\)C. As shown in Figure 9, the temperature at monitoring points on the right side of the fracture (33#, 34#, 35#, 36#) is generally higher than those at the monitoring points on the left side of the fracture (28#, 29#, 30#, 31#). Among the monitoring points on the left and right sides of the fracture, the temperature at point 33#, located on the right side of the fracture, is the highest. This result is primarily attributed to the accumulation of heat on the right side of the fracture. Conversely, the temperature at monitoring point 31# on the left side of the fracture is the lowest, mainly because of the influence of the fracture's thermal barrier. Figure 8: Relationship between peak heating rates at monitoring points and vertical distance from the heat source during the first 2 h of fractured granite heated by an 80 \({}^{\circ}\)C heat source. Figure 9: Temperature variation curves of monitoring points on horizontal line F-F (\(T_{\rm h}\) = 80 \({}^{\circ}\)C). To further explore the influence of the fracture on the heat transfer of granite, the temperature difference between monitoring points on the left and right sides of the fracture at the same \(d_{\rm h}\) was analyzed. The temperature difference between the left and right monitoring points of the fracture under heating conditions ranging from 60 \({}^{\circ}\)C to 90 \({}^{\circ}\)C is shown in Figure 10. From Figure 10, it can be seen that the temperature difference between the left and right monitoring points of the fracture initially increases and then decreases over time within the temperature range of 60 \({}^{\circ}\)C to 80 \({}^{\circ}\)C, eventually stabilizing. When heated by a 90 \({}^{\circ}\)C heat source, the temperature difference between the left and right monitoring points of the fracture rises slowly after 7 h.  
The size of the temperature difference between the left and right monitoring points of the fracture can, to some extent, reflect the degree to which the fracture impedes the heat transfer process of the granite. The temperature difference is greater during the unsteady heat transfer stage of the granite compared to the steady heat transfer stage. It can be seen that the fracture's hindering effect on granite during the unsteady heat transfer stage is more pronounced than in the steady heat transfer stage. The main reason is that in the unsteady heat transfer stage of granite, the presence of the fracture significantly interferes with the heat transfer and distribution process. This is because the heat flow needs to bypass or traverse the fracture, and the stable heat transfer path has not yet been established in this stage due to the granite experiencing a higher heating rate during the unsteady heat transfer stage, which exacerbates the hindrance caused by the fracture of the heat transfer  
Figure 10: Temperature difference change of the left and right monitoring points of the fracture at different temperatures: (**a**) 60 \({}^{\circ}\)C; (**b**) 70 \({}^{\circ}\)C; (**c**) 80 \({}^{\circ}\)C; (**d**) 90 \({}^{\circ}\)C.  
of granite. After entering the steady-state heat transfer stage, although the fracture still affects the heat flow path in the granite, as the heating time increases, the heat balance in the granite is gradually established. The heat flow reaches a stable state, and the distribution of heat in the granite becomes increasingly uniform, resulting in a diminished blocking effect of the fracture on the granite's heat transfer. As observed from Figure 10a-d, the temperature difference between monitoring points 33# and 31# is the largest, whereas the temperature difference between monitoring points 53# and 51# is the smallest.