## 4 Results
### Results of Numerical Simulation  
#### 4.2.1 Deformation Characteristics and Sliding Modes of Slope  
During the excavation stage, we monitored the deformation of the top of the slope and the fourth step, as shown in Figure 8c. We created models for the two most unstable blocks (Model 1 for Block 8 and Model 2 for Block 9) and compared the deformation data of each monitoring point with the actual field measurements (Figure 9). While it is difficult to achieve a perfect match between simulated and actual measurements, we found that the measurements are consistent in scale, and the simulated deformation aligns with the direction of the actual measurements. Both Model 1 (for Block 8--Figure 8a) and Model 2 (for Block 9--Figure 8b) reflect the deformation trend of each monitoring point. Furthermore, both models show tensile plastic zones on the top of the slope and near the cracks, as observed in situ (Section 2.1). After failure, these tensile plastic zones dilate and connect to form a crack (Figure 10a,b), indicating that both models accurately reproduce the cracks observed in situ. The results of deformation measurements and the occurrence of on-site cracks validate both models. \begin{table}
\begin{tabular}{c c c c c c c c} \hline Blocks & 4-1 & 4 & 8 & 8-1 & 8-2 & 9 & 10 & 10-1 \\ \hline FOS & 3.78 & 1.98 & 1.25 & 2.38 & 2.58 & 1.28 & 1.56 & 2.10 \\ \hline \end{tabular}
\end{table} 
Table 6: FOS of LEM. Figure 8: **(a)** Block 8. **(b)** Block 9. **(c)** The location of the in situ monitoring points. Figure 10 shows the failure characteristics of each model and reveals the difference in deformation features between the two models:  
1. The sliding surface of Model 1 is exposed on the slope surface (Figure 10a). The unexcavated part on the right is significantly deformed, which means the sliding block is pulling the unexcavated part of the rock mass. The coalescence of the plastic tensile zone appears on the 3 rd, 5 th, 7 th and 8 th steps (Figure 10c). 2. The most significant deformation area of Model 2 is at the left (Figure 10b). The scope of the failure parts is shown in Figure 10d. The tensile plastic zone appears on the slope surface after failure and is distributed in a wider range than Model 1. To compare the failure areas of the two models, the maximum shear strain increment of the sliding surface after failure was analyzed in Figure 11:  
1. The maximum shear strain increment is concentrated at the lower and top of the sliding surface, creating a banded concentration area in Model 1 (refer to Figure 11a). This area is very close to the daylight of the potential sliding surface. The shear strain increment area gradually diffuses to the right, indicating that the rocks in the concentrated area exert a strong drawing effect on the unexcavated rock mass. The drawing effect caused by the banded area of the sliding surface can easily lead to slope cracking and the formation of a sliding block. The forming process of this band will be discussed in Section 5.2. The sliding block may deform asymmetrically, potentially leading to rotational failure on the plane. The sliding surface of Model 1 is exposed on the slope surface, forming a sliding block. This failure mode reflects cracking from the back edge, as reported by [PERSON] [4]. 2. In Model 2 (Figure 11b), the maximum shear strain increment is concentrated at the middle and top of the slope and diminishes at the lower part. This indicates that the deformation of the entire potential sliding surface is impeded at the bottom. The bottom of the slope strongly constrains the sliding body. When the upper rock experiences significant pressure, the sliding body is susceptible to buckling failure in the middle. Even slight deformation in the middle of the sliding body can result in a substantial bending moment. [PERSON] et al. [2] suggested that this locking phenomenon may be caused by the front edge of the slope. Figure 9: (**a**) X displacement of monitoring point 1. (**b**) Y displacement of monitoring point 1. (**c**) Z displacement of monitoring point 1.