## 3 Stability Analysis of Roadways Under High Horizontal Stress Conditions
### Stability Analysis of Surrounding Rock Under Different Side Pressure Coefficients  
To examine the distribution of horizontal stress in the surrounding rock under different lateral pressure coefficients, numerical simulations are conducted for four conditions: 1.8, 1.9, 2.0, and 2.1. The simulation results are shown in Figure 10. Based on the simulation results, the curves of horizontal stress variation with distance from the roof and floor of the roadway under different lateral pressure coefficients are plotted, as shown in Figure 11.  
Figure 10: Horizontal stress in surrounding rock under different lateral pressure coefficients. (**a**) 1.8, (**b**) 1.9. (**c**) 2.0. (**d**) 2.1.  
Figure 9: Surrounding rock deformation curve under different roadway angles.  
The analysis of Figures 10 and 11 shows the following:  
1. As the lateral pressure coefficient increases, the horizontal stress in the surrounding rock also increases. The peak value of the horizontal stress on the roof ranges from 21.2 MPa to 34.9 MPa, occurring 3 m from the roof. The peak value of the horizontal stress on the floor ranges from 17.2 MPa to 27.6 MPa, occurring 6 to 7 m from the floor.
2. As the distance between the roof and floor increases, the horizontal stress also increases. The horizontal stress reaches its peak at 4 m from the roof and 6 m from the floor. After reaching the peak stress, the horizontal stress rapidly drops to about half of the peak stress. Then, after stabilizing at a distance of 2-3 m, the stress increases slightly and remains stable, while the stress above the roof decreases after stabilizing over 4 to 5 m. Finally, the stress gradually stabilizes at positions 10 m from the roof and 8 m from the floor.  
To examine the deformation of the roadway under varying lateral pressure coefficients, numerical simulations are conducted for four conditions: 1.8, 1.9, 2.0, and 2.1. The simulation results are shown in Figure 12. Based on the simulation results, the deformation curves for different lateral pressure coefficients are plotted in Figure 13.  
Analysis of Figures 12 and 13 reveals the following:  
1. As the lateral pressure coefficient increases, the deformation generally exhibits an upward trend. The deformation increases sharply when the lateral pressure coefficient rises from 2.0 to 2.1. The roof subsidence is 44 mm, 135 mm, 192 mm, and 325 mm, respectively; the floor heave is 23 mm, 55 mm, 74 mm, and 114 mm; and the side convergence is 30 mm, 70 mm, 100 mm, and 200 mm.
2. When the side pressure coefficient is 1.8, the overall deformation of the roadway is small, and the surrounding rock is within the control range. With the increase of the side pressure coefficient, the deformation of the roof increases most obviously, while the increase of the floor and the two sides is small. However, when the side pressure coefficient is from 2.0 to 2.1, the deformation of the surrounding rock increases greatly. The deformation of the roadway roof and sides shows a positive correlation with the lateral pressure coefficient, indicating that controlling the roof and sides will become significantly more difficult.  
Figure 11: Distribution law of horizontal stress in surrounding rock under different lateral pressure coefficients.  
Numerical simulation analysis of roadway excavation shows that the included angle between the direction of the \(\sigma_{\rm H}\) and the strike of the roadway, along with the lateral pressure coefficient, has a significant influence on stability. Consequently, for roadways subjected to high levels of stress, developing a rational support scheme is crucial to ensuring the safety and stability of the roadway.  
Figure 12: Surrounding rock deformation under different lateral pressure coefficients. (**a**) 1.8. (**b**) 1.9. (**c**) 2.0. (**d**) 2.1.  
Figure 13: Surrounding rock deformation curve under different lateral pressure coefficients.