## 7 Conclusions  
The study employs a combination approach of theoretical analysis, physical similarity simulation, numerical simulation, and field measurement to investigate the deformation mechanism of surrounding rock in the RR during the final extraction of the 3301 working  
Figure 14: Surrounding rock deformation curve of ERR.  
Figure 13: Sectional diagram of support parameters of RR before end mining breakthrough.  
face in the Hanjiawan Coal Mine located in the Shendong mining area. It analyzes the instability characteristics of the main roof during the final extraction and retreat of a fully mechanized working face, clarifies the load distribution pattern of the RCP in the working face, and optimizes the support parameters for the RR. The following main conclusions are obtained: (1) The stability of the RCP and the location of the main roof rock beam fracture are primary factors inducing large-scale roof pressure and support crushing when the working face interconnects with the RR during the final extraction stage. It is clarified that when the working face and the RR are interconnected, the fracturing of the main roof behind the support that forms a cantilever beam structure above the RR is most conducive to the safe retreat of the working face. (2) Theoretical analysis reveals that the width of the limit plastic zone in the RCP in the Hanjiawan Coal Mine is 5.5 m, which indicates that the appropriate stopping and pressure-relief position is 5.5 m from the working face. It analyzes the stress distribution pattern of the RCP during the final extraction stage, quantifies the linear relationship between the load acting on the advanced coal pillar and its strength, and determines that yielding and failure occur when the width of the RCP is 2.3 m. (3) The instability characteristics of the main roof during the final extraction stage are elucidated through physical similarity simulations. The instability pattern of the roof structure varies when the working face, after stopping and pressure-relief at the position 5.5 m from the RR, interconnects with the RR. This verifies the accuracy of the theoretically determined stopping and pressure-relief position. (4) The UDEC numerical simulation software was used to optimize the support parameters of mesh and cables for the RR roof. The proposed control technology that integrates \"mesh, cables, and caving-style supports\" effectively maintains the stability of the surrounding rock in the RR during the retreat stage, which demonstrates promising application results.  
Conceptualization, B.W. and J.Z.; methodology, B.W. and H.L. ([PERSON]); validation, B.W. and D.L.; investigation, B.W., D.L. and H.L. ([PERSON]); data curation, B.W.; simulation experiment, B.W., D.L. and H.L. ([PERSON]); numerical simulation, B.W.; writing--original draft, B.W.; writing--review and editing, B.W.; supervision, J.Z. and H.L. ([PERSON]); project administration, B.W.; funding acquisition, B.W. All authors have read and agreed to the published version of the manuscript.  
This project was supported by the National Natural Science Foundation of China (Grant No. 52404144), the Natural Science Basic Research Program of Shaanxi (Program No. 2024 JC-YBQN-0594), and the Postdoctoral Research Project Funding of Shaanxi Province (Program No. 2023 BSHEDZZ298).  
Not applicable.  
The data used to support the findings of this study are available from the corresponding author upon request.  
We thank the National Natural Science Foundation of China, the Natural Science Basic Research Program of Shaanxi, and the Postdoctoral Research Project Funding of Shaanxi Province for their support to this study. We thank the Academic Editors and anonymous reviewers for their kind suggestions and valuable comments.  
Author [PERSON] was employed by the company Shaanxi Yongxin 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.