## 2 Laboratory Investigation of the Effect of a Landslide on Stabilizing Piles
### Experimental Model  
The landslide model is designed based on the physical and mechanical parameters of the bedrock and discontinuities. On the trailing edge of the landslide, a horizontal thrust is applied to study the influence of the force and deformation characteristics of the landslide bed on the block.  
The testing system consists of three parts, i.e., the data acquisition device, the frame of the landslide model and the loading device. The horizontal load is applied by a jack. The displacement of the pile head and the force in the stabilizing pile under different conditions are monitored. The layout of the test model is shown in Figure 1, and the frame diagram is shown in Figure 2. The testing device contains the sliding body, the loading device, the sliding bed, the stabilizing pile, and the monitoring equipment.  
The frame dimensions are 160 cm \(\times\) 76 cm \(\times\) 100 cm (see Figure 2). One side of the frame is an 8 cm thick tempered glass, so continuous monitoring of deformation of the sample is a convenient process in the experiment. The size of the stabilizing pile is 2 cm \(\times\) 3 cm \(\times\) 70 cm, and the embedded length of the pile is 30 cm.  
The jack was used to load the trailing edge of the sample. The loading was divided into five stages, and the standard procedure for each stage of the loading was to move the trailing edge by 3 cm. The thrust at the trailing edge of the sample was measured by the pressure sensor placed at the top of the jack during the loading process. The strain of the pile was measured using strain gauges. Fourteen strain gauges were used along the length of the pile and seven gauges were used on each side with a 10 cm spacing between them, as shown in Figure 3.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Rock Type**} & **Density \(\rho\)** & **Elastic Modulus E** & **Poisson’s Ratio \(\mu\)** & **Cohesion \(c\) (MPa)** & **Friction Angle \(\varphi\) (\({}^{\circ}\))** & **Tensile Strength (MPa)** \\ \hline Mudstone & 2.43 & 15.3 & 0.27 & 2.99 & 33.3 & 2.8 \\ Sandstone & 2.63 & 27.3 & 0.16 & 6.63 & 50.4 & 4.9 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Material parameters of the bedrock.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{3}{c}{**Bedding Plane**} \\ \cline{2-4}  & **Mudstone** & **Sandstone** & **Sandstone-Mudstone** \\ \hline Cohesion \(c\) (MPa) & 0.35 & 0.45 & 0.24 \\ Friction angle \(\varphi\) (\({}^{\circ}\)) & 30.36 & 38.56 & 33.8 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Shear strength parameters of the bedding plane.  
The sliding bed is prepared in 4 different rock layers and the sliding body is a whole part. In the process of the experimental model, each layer of sliding bed is casted by one-time casting. The bottom rock layer is casted according to the experimental scheme, and it needs to be emphasized that each rock layer should be cured with four days to obtain the basic strength. Subsequently, the stabilizing pile is fixed on the bottom rock layer, then the second layer, the third layer and the fourth layer were placed respectively. Finally, the sliding body was placed.  
To minimize the boundary effects on the test results, three stabilizing piles were used in the model, and the top displacement of the middle pile was measured through the dial indicator. The arrangement of the stabilizing pile and the dial indicator is shown in Figure 4.  
Figure 1: Landslide test model framework.  
Figure 2: Functional block diagram of the pile–landslide physical model: (**a**) side view (**b**) top view.