## 4 Simulation Analysis of Key Roof-Cutting Parameters for GSER
### Analysis of Simulation Results
Within the same burial depth range, as the cutting angle increases, the vertical stress shifts towards the solid coal side, and both the vertical displacement and stress peak of the retained roadway roof show a decreasing trend, albeit with diminishing reductions. When comparing various scenarios, the maximum displacement and stress peak of the roof are significantly larger when the cutting angle is \(0^{\circ}\) or \(5^{\circ}\), indicating that smaller cutting angles result in greater sliding resistance between the cuts, making it difficult for the gob-side roof to collapse completely under dynamic pressure. Additionally, the deflection of the roof cantilever structure contributes to larger displacement and stress on the retained roadway roof. As the cutting angle increases, the peak stress concentration on the solid coal side gradually increases, suggesting that blindly increasing the cutting angle does not continuously enhance the benefits. Furthermore, due to field construction constraints, increasing the cutting angle prolongs the drilling cycle, significantly affecting the progress of underground roof-cutting and pre-splitting projects. Stability analysis of the roadway cross-section in different cutting scenarios of the 9306 working face was conducted using the strength reduction method. According to this method, the mechanical parameters of the rock mass (internal friction angle C and cohesion  
Figure 10: Vertical displacement and stress peak curves of the retained roadway roof for each cutting scheme. \(\varphi\)) were altered until the limit equilibrium state was reached, and the reduction factor at this point was defined as the safety factor [44; 45]. Under different simulation scenarios, the reduction of the surrounding-rock parameters of the roadway cross-section started from 1 and increased incrementally by 0.1. When the displacement growth rate of the control points suddenly increased, indicating instability of the roadway, the reduction was performed incrementally by 0.02 as the instability stage approached. The safety factors of the roadway under different scenarios are summarized in Table 4. Analysis revealed that by selecting reasonable roof-cutting parameters, all scenarios could ensure that the safety factor of the roadway was above 1.68. Within the same burial depth range, as the cutting height and cutting angle increased, the safety factor of the roadway gradually increased, but the rate of increase gradually decreased. Therefore, when determining the roof-cutting parameters, it is necessary to comprehensively consider the balance between drilling construction costs and roadway stability. Based on theoretical analysis and the numerical simulation results, considering the variability in burial depth within the coal seam region of the karst mountainous area, a cutting angle of 10\({}^{\circ}\) is able to effectively ensure the long-term stability of the retained roadway roof without being limited by the duration of drilling. Specifically, when the burial depth is below 400 m, Scenario 2 is suitable; when the burial depth is between 400 m and 500 m, Scenario 7 is appropriate; and when the burial depth is above 500 m, Scenario 9 is recommended.