# Evolution Process of Toppling Deformations in Interbedded Anti-Inclined Rock Slopes
## 2 Materials and Methods
### Model Configuration  
This physical model test was conducted using a self-developed automated base friction test apparatus (Figure 1). Place the two-dimensional slope model horizontally on the conveyor belt. Constrained by a fixed model frame, the slope model does not move horizontally with the conveyor belt. As shown in Figure 1a,b, when the conveyor belt moves from right to left, the sliding friction between the conveyor belt and the model can effectively replace the gravity force acting on the two-dimensional slope model. As shown in Figure 1b, the slope surface is free within the horizontal plane to simulate the movement of the slope when under the effect of gravity. The base of the slope model is set as fixed boundaries to prevent overall movement and ensure a stable application of frictional forces on the model base surface when the conveyor belt is operating. The lateral sides of the model are each designed as free in the movement direction of the conveyor belt. The test process can be recorded through a Gopro camera located above the slope model. The speed of the conveyor belt can be adjusted from 0 to 50 r/min. Before the formal test, we used a dynamometer to measure the value of \(\mu\) at different speeds. It can be seen that at 50 r/min, the dynamic friction coefficient reached its maximum value (\(\mu\) = 0.484),  
Figure 1: Base friction test apparatus: (**a**) Side view of the apparatus; (**b**) Panoramic photograph of the apparatus; (**c**) Schematic diagram of the apparatus. with the lowest data dispersion (Figure 2). To ensure the stability of the test process, the speed of the conveyor belt was set to 50 r/min for this test. According to the dimensions of the model frame of the test apparatus and the actual dimensions of the typical interbedded rock slopes located in the upper Yalong River of southwest China [38], the value of \(C_{L}\) is determined to be 1000. The value of \(C_{\varphi}\) and \(C_{\gamma}\) are both determined to be 1. According to Equation (3), it can be derived that \(C_{\varphi}=2066\). The field study shows that the interbedded rock slopes located in the study area are primarily composed of phyllite and metasandstone [38]. The parameters of intact rocks and discontinuities were determined via uniaxial compression tests, Brazilian tests and direct shear tests conducted in the laboratory. The mean values of the test results are presented in Tables 1 and 2. The similar materials of metasandstone and phyllite were made by mixing iron powder, quartz sand, parite powder, clay, and gypsum [43]. The configuration scheme of two similar materials was obtained by trial and error to meet the requirements of the similarity conditions as closely as possible. A summary of the physical and mechanical properties for the optimal similar materials is presented in Tables 1 and 2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Material Type** & **Density (kg/m3)** & **Elastic Modulus (GPa)** & **Cohesion (Mpa)** & **Internal Friction Angle (\({}^{\circ}\))** & **Tensile Strength (MPa)** \\ \hline Phyllite & 2700 & 6.0 & 3.0 & 40.0 & 5.0 \\ Target value 1 & 2700 & 2.9 \(\times\) 10\({}^{-3}\) & 1.45 \(\times\) 10\({}^{-3}\) & 40.0 & 2.4 \(\times\) 10\({}^{-3}\) \\ Similar material 1 & 2636 & 4.8 \(\times\) 10\({}^{-3}\) & 2.82 \(\times\) 10\({}^{-3}\) & 43.3 & 4.5 \(\times\) 10\({}^{-3}\) \\ Metasandstone & 2600 & 11.0 & 7.0 & 45.0 & 9.0 \\ Target value 2 & 2600 & 5.3 \(\times\)10\({}^{-3}\) & 3.4 \(\times\) 10\({}^{-3}\) & 45.0 & 4.3 \(\times\) 10\({}^{-3}\) \\ Similar material 2 & 2480 & 6.7 \(\times\) 10\({}^{-3}\) & 4.8 \(\times\) 10\({}^{-3}\) & 48.7 & 6.1 \(\times\) 10\({}^{-3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters of the intact rock and similar materials.