## 5 Numerical Analysis Results and Discussion
### PLAXIS Analysis
#### 5.3.3 Case Simulation of Site 3  
Table 15 displays the soil properties for Site 3, Tables 16-18 display the material specifications of the slope protection structures at Site 3, and Figure 31 displays Site 3's analysis model. The retaining wall is shown by the blue line, the ground anchor's free section is shown by the black line, and the anchor segment is shown by the red line. From top to bottom, the soil layer is separated into a colluvial layer, and sandstone and shale that are interbedded. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Soil Layer**} & \multicolumn{5}{c}{**Parameters**} \\ \cline{2-7}  & \(\gamma_{\text{unsat}}\) & \(\gamma_{\text{sat}}\) & \(E\) & \(\
u\) & \(c\) & \(\varphi\) & \(\psi\) \\  & **(kN/m\({}^{3}\))** & **(kN/m\({}^{3}\))** & **(kN/m\({}^{2}\))** & & **(kN/m\({}^{2}\))** & **(\({}^{5}\))** & **(\({}^{5}\))** \\ \hline Colluvial layer & 18.6 & 19.1 & \(7\times 10^{4}\) & 0.3 & 10 & 28 & 0 \\ Interbedded sandstone and shale & 25.5 & 26.0 & \(3\times 10^{5}\) & 0.3 & 50 & 35 & 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Soil parameters of Site 3. Figure 30: Site 2’s \(\Sigma\)_Msf_ in various scenarios. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Scenarios**} & \multicolumn{3}{c}{**Safety Factor**} \\ \cline{2-5}  & **Simulation Result** &
\begin{tabular}{c} **Design** \\ **Specification** \\ \end{tabular} \\ \hline Scenario 1: Normal groundwater level & 1.265 & \(\geqq 1.5\) \\ Scenario 2: High groundwater level & 1.105 & \(\geqq 1.2\) \\ Scenario 3: Normal groundwater level and & 1.009 & \(\geqq 1.1\) \\ \hline \hline \end{tabular} Note: Initial value of safety factor for Site 2 at normal groundwater level without slope protection facilities = 1.078.  
\end{table} 
Table 14: Safety factor for Site 2 in various scenarios. Table 19 displays Site 3's displacement in each scenario. The contour line diagrams of the slope displacement in various scenarios are displayed in Figures 32-34. Figure 32 indicates that the force acting on the slope was focused below the ground anchor since Site 3 was at the normal groundwater level. However, as Figure 33 illustrates, the force acting on the slope was focused at the top in the high groundwater level scenario. The pseudo-static analysis result seen in Figure 34 revealed that the force acting on the slope extended from the slope's top to its toe when seismic conditions were included. The force acting on the slope was found to be centered beneath the ground anchors. Figures 35-37 show the potential sliding surface based on safety analysis in different scenarios at Site 2. In Scenario 1, the potential failure surfaces of the slope were mostly located behind the ground anchors, but some penetrated through the lower ground anchors, as shown in Figure 35. In Scenario 2, the potential failure surfaces of the slope were raised \begin{table}
\begin{tabular}{c c c c c c} \hline
**Simulation** & **Material Type** & **Axial Stiffness** & **Elevural Stiffness** & **Weight** & \\
**Elements** & **Modelulus** & **Weight** & **(kN/m)** & **(kN\({}^{2}\)/m)** & **(kN/m)** & **\(\
u\)** \\ \hline Plate element & Elasticity & \(7.53\times 10^{6}\) & \(56,475\) & \(7.2\) & \(0.17\) \\ \hline \end{tabular}
\end{table} 
Table 16: Parameters of retaining wall materials of Site 3. Figure 31: PLAXIS 2D model for Site 3. \begin{table}
\begin{tabular}{c c c c c} \hline
**Simulation Elements** & **Material Type** & **Axial Stiffness** & **Horizontal Spacing** & **Pre-Force** \\
**Node-to-node anchor element** & Elasticity & \(2\times 10^{5}\) & \(2.5\) & \(600\) \\ \hline \end{tabular}
\end{table} 
Table 18: Material parameters of free section of ground anchor of Site 3. Figure 39 shows Site 3's \(\Sigma Msf\) curve in different scenarios. The SF was determined from the ordinate value after the curve in the figure reached the stable stage. As Table 20 shows, the SFs of Scenarios 1, 2, and 3 were 1.405, 1.306, and 1.021, respectively.