## 5 Conclusions  
In the No.6 and No.7 transportation roadways of the middle section of Baoxiu-120 at the Shilu Iron Deposit, significant rock mass failures, including roof caving and rib spalling, were observed. A comprehensive assessment classified the rock mass in this section as level IV based on data obtained from field investigations, structural surface analyses, drilling activities, and laboratory rock experiments.  
Figure 7: Displacement of roadway roof and surrounding rocks on two sides.  
Informed by this evaluation and the support guidelines derived from geomechanical classification methods, a joint support system comprising anchor mesh and shotcrete was implemented. The design parameters for the support structure at Shilu Iron Deposit were established as follows: the shotcrete was applied with a thickness of 55 mm, using a mix of Portland cement, medium-fine sand (with particle sizes smaller than 2.5 mm), and stones (with particle sizes smaller than 15 mm) in a weight ratio of 1:2:2. The water-cement ratio was maintained between 0.3 and 0.4. Additionally, resin bolts with an outer diameter of at least 20 mm and a length of 2200 mm were employed, with row and column spacings set at 1100 mm. A rectangular metal mesh with dimensions of 80 \(\times\) 80 mm served as the anchor mesh. Digital convergence gauges were utilized to monitor deformations within the roadway. In the initial five weeks following the implementation of the support system, significant changes in convergence deformation rates were recorded, with displacements exceeding 20 mm at the sides and roof of the roadway. However, after one month, the convergence deformation rates rapidly decreased and stabilized. The adopted support patterns effectively controlled displacement and mitigated stress concentration within the surrounding rocks, thereby ensuring the overall stability of the roadway.  
This case highlights the importance of conducting thorough rock mass quality assessments prior to support design. The timely recognition of changes in rock mass quality and the subsequent redesign of support structures are critical for maintaining stability in underground environments. By integrating continuous monitoring and adaptive design practices, we can enhance the safety and effectiveness of support systems in similar geological settings.  
Methodology and visualization, C.M., P.W. and J.L.; writing--original draft preparation, C.M., P.W., J.L. and X.F.; writing--review and editing, Z.D., Z.C., X.F. and X.W. All authors have read and agreed to the published version of the manuscript.  
This work was financially supported by the National Key R&D Program of China (No. 2023 YFC2907400, 2021 YFC2900500), the Hainan Province Science and Technology Special Fund (ZDYF2024 GXJS307), and the National Natural Science Foundation of China (No. 52074020).  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
We acknowledge the valuable advice of the editors and reviewers.  
Author [PERSON] was employed by the company Hainan Mining 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.