## 6 Discussion  
1. Before the single support pillar fractures, both sides of the support system experience pronounced loosening and spalling, while the roof exhibits minimal subsidence. After the fracture occurs, the overburden rock layers undergo severe damage and fail to support loads, increasing the risk of toppling accidents.
2. Field observation data show that the two sides across the three measurement stations experience 104.858 mm convergence on average, which is noticeably larger than the mean roof subsidence (i.e., 46.000 mm). This indicates that the surrounding rock failure occurs on both sides. In contrast, when the existing support parameters are optimized, the simulated roof subsidence and side convergence are comparable, reaching 24.071 mm and 23.478 mm, respectively, or 0.48 m and 0.47 m in the real-world scenario. This result indicates that the optimized support scheme effectively controls the convergence of the surrounding rock.
3. The peak support pressure occurs approximately 16 cm from the coal side, representing 3.2 m in actual conditions. Within the range from the coal side to the peak support pressure, the surrounding rock on both sides is prone to fragmentation and plastic deformation. Through similar material simulation experiments, the optimized loosening and damage range for the left and right sides of the opening cut are 7.3 cm (1.46 m in the field) and 6.1 cm (1.22 m in the field), respectively. Compared to the theoretical calculation of the plastic failure range of 1.83 m under the original design support parameters, the optimized support parameters effectively control the loosening and damage range of both sides of the opening cut.
4. Data from three delamination measuring stations indicate that the delamination range of the overburden rock layer above the opening cut is between 0 and 5 m, with almost no delamination occurring between 5 and 8 m, suggesting stability of the roof rock layer at a depth of approximately 5 m. The use of 8.3 m rock cables in the field risks penetrating water-bearing layers, leading to water ingress and softening of the overburden rock, which complicates excavation support. It is recommended to shorten the cable length to 6 m. Observations from the experimental model show that the delamination range of the optimized support parameters is 12.3 cm (2.46 m in the field), indicating that shortening the cable length prevents large-scale loosening of the roof rock layer, making the optimized cable parameters feasible.
5. Observations reveal that the average delamination values for the roof rock layers at depths of 1-3 m and 3-5 m are 9 cm and 15 cm, respectively, with the delamination in the 3-5 m range being significantly greater than in the 1-3 m range. This suggests that the top rock rods are effective in controlling fragmentation in the upper rock layers but less effective for deeper rock layers. Through theoretical calculations, it is recommended to increase the length of the top rock rods, with a reasonable length suggested to be 3 m. Theoretical calculations recommend increasing the length of the top rock rods, with a reasonable length suggested to be 3 m. Simulation experiments indicate that the delamination of the optimized roof rock layer is only 12.3 cm (2.46 m in the field), and delamination in the 15-25 cm range (3-5 m in the field) is absent, confirming the feasibility of the top rock rod support scheme.  
The on-site monitoring data show good consistency with the simulation experiment results. The optimized support parameters effectively constrained rib convergence and reduced loosening failure zones in open off-cut ribs. Comparative analysis of field monitoring data and simulation results validated the practical applicability of the optimized scheme, demonstrating its effectiveness. Critical control parameters for large-section open off-cut support were identified, enabling rational determination of support configurations including cable bolts and roof bolts.