# Study on the Distribution Law of Crustal Stress in Fault Fracture Area
## 5 Conclusions  
The article focuses on analyzing the impact of fault structure and the degree of fault fragmentation on the distribution of ground stress through numerical simulations. The results of the study reveal the following findings:  
1. Presence of Fault Fracture Zone: When a geological area is influenced by tectonic stress and contains a fault fracture zone, the magnitude and direction of the main stress are disturbed by the fault. The degree of disturbance depends on factors such as the differences in deformation characteristics between the fault and ordinary strata, the degree of fault fragmentation, and the angle between the fault strike and the main stress direction.
2. Deformation Characteristics and Fault Fragmentation: The differences in deformation characteristics between faults and ordinary strata primarily affect the degree of stress change. Larger differences result in greater degrees of change. The degree of fault fragmentation affects the distribution of crustal stress within the fault, causing fluctuations from the original state. The angle between the fault strike and the main stress direction directly influences the direction and magnitude of the deviation of the main stress.
3. Angle \(\alpha\) Less Than 45\({}^{\circ}\): When the angle \(\alpha\) between the maximum horizontal principal stress direction and the vertical fault direction is less than 45\({}^{\circ}\), the internal \(\sigma_{1}\) and \(\sigma_{3}\) within the fault increase, while the surrounding rock area near the fault slightly decreases. Moreover, the direction of \(\sigma_{1}\) inside the fault deflects parallel to the fault, while \(\sigma_{1}\) near the outside of the fault experiences slight deflection in the direction of the vertical fault. When \(\alpha=0^{\circ}\), the direction of principal stress remains unchanged.
4. Angle \(\alpha\) Greater Than 45\({}^{\circ}\): When the angle \(\alpha\) between the maximum horizontal principal stress direction and the vertical fault direction exceeds 45\({}^{\circ}\), the \(\sigma_{1}\) and \(\sigma_{3}\) inside the fault decrease, whereas \(\sigma_{1}\) and \(\sigma_{3}\) in the surrounding rock area near the fault increase. Additionally, the \(\sigma_{1}\) direction inside the fault deflects perpendicular to the fault trend, while the \(\sigma_{1}\) deflection direction near the outside of the fault is the opposite. When \(\alpha=90^{\circ}\), the direction of principal stress remains unchanged.
5. Project Considerations: The variation of ground stress caused by faults should be considered in engineering projects. In high-stress hard rock tunnels, stress concentration at fault edges may increase the likelihood of rock bursts. Therefore, measures should be taken to strengthen the affected areas and minimize the risk to ensure the safety of the construction process.  
H.-L.F.: Conceptualization, Methodology, Supervision, Project administration. W.X.: Methodology, Software, Data processing, Writing, original draft. Y.-M.W.: Validation, Formal analysis, Writing, review, and editing. All authors have read and agreed to the published version of the manuscript.  
This work was supported by Research on the Mechanism and Control Technology of Rock Bursts in Super Deep Tunnels by National Railway Group Co., Ltd. (19-15-02), National Natural Science Foundation of China (51978668).  
The authors thank the Advanced Research Center, Central South University, for providing the experiment conditions. The authors also express special thanks to the editors and anonymous reviewers for their constructive comments.  
The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.