# Study on Damage Behavior and Its Energy Distribution of Deep Granite at High-Temperature Conditions
## 5 Conclusions and Future Work  
The research results are as follows:  
1. With the increase in confining pressure, the peak stress and corresponding strain of rock samples with similar equivalent damage factors increase. However, compared with the same confining pressure rock specimens of different initial thermal damage found that when the confining pressure is the same, the greater the confining pressure, the difference in peak stress of different initial thermally damaged samples becomes smaller and smaller, when the confining pressure is 0 MPa, the maximum difference of peak stress is 6 MPa, but when the confining pressure is 10 MPa and 20 MPa, the peak stress is almost identical, and the difference of corresponding peak strain does not decrease with the increase in confining pressure, and is always stable between 0.006 and 0.007. The results show that the peak stress is sensitive to confining pressure and the peak strain is sensitive to the equivalent fracture damage factor.
2. For rocks with similar equivalent damage factors, the greater the confining pressure, the less the influence of equivalent damage factors inside the rock mass on the failure mode. The evolution of dissipated energy ratio of specimens with different initial thermal damage is similar in the compression deformation failure process under different confining pressures, and all specimens experience four stages, rapid increase \(\rightarrow\) rapid decline \(\rightarrow\) steady at a certain value \(\rightarrow\) rapid rise. In addition, the proportion of dissipated energy of samples with equivalent damage factor D = 0.89 is significantly higher than that of other damaged samples, indicating that the development of internal cracks in granite samples is mutational, and the internal cracks in rock develop rapidly when the thermal stress reaches the threshold value of crack propagation.
3. Under the same fracture degree, the maximum energy dissipation changes greatly with the increase in confining pressure. Under the same confining pressure, the maximum energy dissipated during rock failure increases slowly first and then decreases rapidly with the increase in fracture degree. Taking 20 MPa as an example, the maximum dissipated energy density remains stable at 3.5-3.6 MJ\(\cdot\)m\({}^{-3}\) at D = (0.4-0.5). Before this, the dissipated energy density increases monotonically, and then slowly decreases. Therefore, there is a maximum inflection point at the fissure D = (0.4-0.5). So, when the internal fracture degree of rock mass D = (0.4-0.5), it can be used as the discriminant basis for critical support in engineering support.  
Figure 12: The schematic diagram of the internal fracture degree of rock mass with surrounding rock deformation.  
**Author Contributions:** Conceptualization, Q.L.; Methodology, M.Z.; Validation, M.Z.; Formal analysis, M.Z.; Investigation, J.Y.; Resources, L.Q.; Data curation, Q.L. and J.Y.; Writing--original draft, M.Z.; Supervision, Q.L.; Project administration, L.Q.; Funding acquisition, L.Q. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the National Natural Science Foundation of China, grantnumber 52274107 and Interdisciplinary Research Project for Young Teachers of USTB (FRF-IDRY-GD21-001).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Some or all data, models, or codes generated or used during the study are proprietary or confidential in nature and may only be provided with restrictions.  
**Conflicts of Interest:** The authors declare no conflict of interest.