## 5 Conclusions  
The stress-structural failure mechanism that occurs in the excavation of the left-side tunnel section of 610 m crushing station in Jinchuan II mine is investigated herein. The main causes and key controlling factors contributing to the formation of the mechanism and failure characteristics are discussed. The main conclusions, suggestions, and future research directions are as follows:  
The instability of the surrounding rock in the left-side tunnel section of the 610 m crushing station is controlled by the contact area between the reddish-brown granite stratum and the gray-black-gray gneiss stratum, as well as the in-situ stress field. The stress-structural inducement is that the excavation and unloading of the crushing station causes joint sets (JSet #2 and JSet #3), and the excavation face causes the formation of unfavorable blocks. Thus, stress-structural failure caused by jointing in the formation of the tunnel section is one of the key issues concerning the instability of the surrounding rock during the excavation of the crushing station. To ensure overall stability during the excavation of the left-side tunnel section of the 610 m crushing station, it is recommended to adopt an 'optimized excavation parameter + joint support form' approach to systematically control stress-structural failure at three levels: the surface layer, shallow layer, and deep layer. The following specific measures are recommended: controlling the dosage of explosives used for excavation by blasting; reinforcing advanced support with anchoring; strengthening the surface layer with steel arches and shotcrete; and strictly limiting sidewall damage.  
Figure 10: The left-side tunnel section of 610 m crushing station: (**a**) the distribution of excavation damage zone of surrounding rock (**b**) excavation damage zone distribution and displacement vector diagram (section is 0.5 m from working face); (**c**) displacement vector local amplification diagram.  
The perspective in future research about stress-structural failure in deep engineering should be centered on advancing the understanding of underground rock mechanics and structural behavior, with a clear goal of enhancing safety and operational reliability. Several key areas of focus can be considered: advanced numerical simulation techniques (discrete element and computational fluid dynamics); material characterization and modeling (the development of constitutive models that capture the complex behavior of rock under high-stress conditions); in-situ monitoring and instrumentation (advancements in sensor technology and real-time monitoring systems); and in-situ monitoring and instrumentation.  
Y.K.: conceptualization, methodology, and resources; S.Y.: conceptualization; S.Q.: formal analysis; J.X.: supervision. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Key R&D Program of China (Grant Nos. 2022 YFC2904103); the Key Program of the National Natural Science Foundation of China (52034001); the Program of the National Natural Science Foundation of China (52004152); and the Youth Foundation of the Shandong Natural Science Foundation (ZR2020 QE100).  
Not applicable.  
All data generated or analyzed during this study are included in this published paper.  
[PERSON] was employed by Gansu Jinchuan Group Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.