## 3 Results and Discussion
### Numerical Simulation Analysis
#### 3.4.2 Calculation Results  
The strength reduction method is commonly used in numerical simulation to analyze slope stability. This method uses factor of safety \(F\) to reduce the cohesion and internal friction angle [11]:  
\[c_{1}=\frac{c_{0}}{F_{\rm trial}}, \tag{5}\]  
\[\varphi_{1}=\frac{\varphi_{0}}{F_{\rm trial}}, \tag{6}\] \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Name** & \(\rho\) **(kg\(\cdot\)m\({}^{-3}\))** & \(E\) **(MPa)** & \(c\) **(kPa)** & \(\varphi\) **(\({}^{\circ}\))** & \(v\)** & \(k\) **(cm\(\cdot\)s\({}^{-1}\))** & \(n\) \\ \hline Fully weathering rock & 2100 & 800 & 500.0 & 35 & 0.30 & \(5\times 10^{-3}\) & 0.25 \\ Strongly weathering rock & 2400 & \(1\times 10^{4}\) & 9.0 \(\times\)\(10^{3}\) & 35 & 0.26 & \(2\times 10^{-6}\) & 0.1 \\ Weakly weathering rock & 2500 & \(4\times 10^{4}\) & \(2.5\times 10^{4}\) & 45 & 0.23 & \(1\times 10^{-7}\) & 0.05 \\ \hline \end{tabular}
\end{table} 
Table 7: Geological body parameters. \begin{table}
\begin{tabular}{c c c c} \hline
**Loading Stage** & **Rainfall Intensity (mm\(\cdot\)h\({}^{-1}\))** & **Groundwater Discharge per Mesh (m\({}^{3}\)s\({}^{-1}\))** & **Duration (min)** \\ \hline Rainfall & Stage-1 & 35 & 0 & 10 \\ Stage-2 & 65 & 0 & 10 \\ Stage-3 & 105 & 0 & 30 \\ \hline Hydraulic fluctuation & Stage-4 & 105 & \(5\times 10^{-4}\) & 40 \\ \hline \end{tabular}
\end{table} 
Table 8: Loading scheme of numerical simulation. where \(c_{0}\) and \(\varphi_{0}\) are the initial cohesion and internal friction angle of the geological body, respectively; \(c_{1}\) and \(\varphi_{1}\) are the reduced cohesion and internal friction angle, respectively; \(F_{\text{trial}}\) is the factor of safety selected for each calculation attempt. Figure 14a shows that the initial factor of safety is 1.3, and the maximum shear strain increment of the slope is distributed in large quantities throughout the slope. Figure 14b shows that the factor of safety after support is 2.4, and the maximum shear strain increment is concentrated at the front edge of the strong weathering zone. The existence of tensile cracks and structural planes is an important factor in inducing plane failure. Figure 15 shows the evolution of the pore water pressure contour at the end of each loading stage. Figure 15a shows that the pore water pressure of the slope was small at the end of Stage-1, as the saturated region of the geological body was small at this time. Figure 15b illustrates that at the end of stage 2, the pore water pressure contour of 4.0 kPa was distributed in the shallow layer of the strongly weathering zone, revealing the saturation process of geological bodies under continuous infiltration. Figure 15c shows that the pore water pressure in the shallow layer of the slope increased significantly compared with the first two stages. Figure 15d indicates that the pore water pressure in the strongly weathering zone increased as a whole, and the structural plane evolved into a groundwater seepage channel, which well simulated the physical model test results. Due to the influence of lower porosity or permeability, the pore water pressure in the fully weathering zone and weakly weathering zone were lower than the strong weathering zone. Figure 16 shows the evolution of the displacement magnitude at the end of each loading stage. As shown in Figure 16a, there was almost no displacement at the end of Stage-1. Combined with Figure 15a, it can be seen that the reduction of the effective stress caused by rainfall was weak. Figure 16b shows that the displacement was concentrated in the strongly weathering zone, and the displacement magnitude of the front block is about 0.1 m. Figure 16c shows that the tensile cracks were the dominant infiltration path of rainfall and led to the increase of pore water pressure at this position. At this time, the 1.0 m displacement magnitude contour was distributed on the sixth-level platform.