## 4 Numerical Simulation Study on Stability of Ridge and Slope after Excavation
### Stability of Ridge Slope under Different Exxavation Slope Ratio  
In actual engineering, if the slope height is small, then it can be directly excavated without considering the influence of excavation. The effect of the excavation slope rate was considered only when the slope height was large, so the slope height was set to 30 m in this paper. Figure 15 presents the displacement cloud map of the ridge slope under different excavation slope ratios when \(\alpha\) is \(20^{\circ}\) and \(\beta\) is \(40^{\circ}\). The maximum displacement occurred at the top of the slope under different excavation slope rates, and the greater the excavation slope rate, the greater the displacement at the top of the slope (Figure 15). The displacement of the flank slope also increased with the excavation slope ratio. When the excavation slope ratio was small, the displacement of the  
Figure 14: Schematic diagram of ridge slope excavation model, (**a**) pre-exxavation; (**b**) post-exxavation. Figure 15: The displacement clouds map of ridge slope after excavation under different excavation slope rates (Unit: m). (**a**) The excavation slope ratio is 1:1.5; (**b**) the excavation slope ratio is 1:1.25; (**c**) the excavation slope ratio is 1:1.  
lower part of the ridge slope and the disturbance of the excavation effect on the bedrock at the bottom of the slope were small. However, when the excavation slope rate was large, the bedrock at the bottom of the slope displayed a large displacement, and the area of the bedrock deformation zone was also large. Figure 16 shows the cloud map of the plastic zone of the ridge slope under different excavation slope rates when \(\alpha\) is 20\({}^{\circ}\) and \(\beta\) is 40\({}^{\circ}\). The larger the excavation slope ratio, the larger the plastic zone area and plastic displacement of the ridge slope. When the excavation slope ratio was 1:1.5, the plastic strain of the ridge slope was 2.89, and very little plastic displacement occurred on the excavation surface. When the excavation slope ratio increased to 1:1, the plastic displacement of the excavation slope increased, and even a penetrated plastic zone appeared. A plastic zone also existed in the area of the slope toe. Therefore, appropriate reinforcement treatment was required at the slope foot. Figure 17 shows the relationship between the displacement at the top of the slope and the strength reduction coefficient under different excavation slope rates. The curves of the displacement at the top of the slope with the reduction coefficient at different excavation slope rates. The safety factor of the excavated slope was indeed reduced compared with the original slope. The comparison of the displacement curves of three different excavation slope ratios indicates that the stability coefficient of the slope with a small slope rate was small. When the excavation slope rate was small, the excavation volume was large, and the slope extended to the back of the ridge side slope. The slope surface was greatly affected by the displacement of the trailing edge of the slope, so the stability coefficient of the ridge slope was low at this time (Figure 17). In the calculation of \(H=30\) m, \(\alpha=30^{\circ}\), and \(\beta=40^{\circ}\), even when the excavation slope rate was 1:1, the excavated slope still reached the peak of the ridge when excavating the ridge slope. Therefore, the slope was cut from the top of the ridge slope, and the slope ratio  
Figure 16: The plastic zone cloud map of ridge slope after excavation under different excavation slope rates. (**a**) The excavation slope ratio is 1:1.5; (**b**) the excavation slope ratio is 1:1.25; (**c**) the excavation slope ratio is 1:1. Figure 17: Displacement curves at the top of the slope with different excavation slope ratios. was 1:0.9, which satisfied the road width requirement.