## 5 Application Case
### Process of Numerical Modeling
#### 5.3.3 Modeling of the Excavation of the Seventh to Twelfth Layers  
After the excavation of the seventh layer, the displacement of the south slope continues to increase, and the deformation degree of the mesh increases rapidly, leading to the penetration of the maximum shear strain increment belt of the slope and the instability of the south slope (Figure 14c). After the simulation of a landslide, the unstable part on the south slope is eliminated, and the plastic zones on the north and south slopes are reduced (Figure 14d).  
When the eighth layer is excavated, the way that the south slope is destroyed is similar to that of when the fifth layer was excavated. The earth pressure inside the north slope is relatively high because of the excavation at the foot of the slope, and this is the penetration of the maximum shear strain increment belt. As shown in Figure 14e, the numerical calculation is not convergent at this time, indicating that a landslide occurs. Therefore, the landslide is simulated by the method proposed in this paper.  
After the third landslide, the north and south slopes were in a stable state with a relatively high safety factor. The excavation of the ninth layer ore body had little effect on the stability of the north and south slopes. Figure 15 shows the plastic zone of the slope after excavation. Although penetration of the plastic zone occurs, the numerical calculation converges. This shows that the slope is in a critical state.  
According to the excavation of the seventh and eighth layers, the excavation of the ore body at this stage has a great influence on the stability of the slope: with the increase in the excavation depth, the north and south slopes alternately lose stability. This behavior is repeated when excavating the tenth and eleventh layers. These layers are located near the fault, so the slope is less stable there. When the tenth layer is excavated, the numerical calculation does not converge, and the south slope is unstable. The penetration of the maximum shear strain increment belt occurs (Figure 14e). After simulating the landslide on the southern slope, the plastic zone of the slope did not penetrate the slope completely, and the slope was stable (Figure 14f). When excavation is performed on the eleventh layer, the top rock mass of the ore body loses the support of the ore layer, so the rock body collapses and causes a landslide, the penetration of the maximum shear strain increment belt occurs and the meshes exhibit obvious distortion. The numerical calculation does not converge, and the slope is unstable (Figure 14g). After simulating the landslide on the southern slope, the plastic zone of the slope did not penetrate the slope completely, and the slope was stable (Figure 14h).  
When the eleventh layer of the vein is excavated, the maximum shear strain increment belt of the south slope is not completely penetrated (Figure 14g), and the numerical  
Figure 15: The plastic zone after mining the ninth layer.  
calculation converges, leaving hidden dangers for the subsequent stability of the south slope. Therefore, the south slope is already in a critical state when excavating the twelfth layer (Figure 16).