## 2 Materials and Methods
### Basic Physical Properties  
The Hipparion laterite samples collected from the landslide slide zone underwent laboratory testing to determine the basic physical properties and soluble salt content. The results of these tests are presented in Tables 1 and 2.  
Figure 2: Landslide engineering geological profile.  
The mineral composition testing of the Hipparion laterite samples was conducted using the XD-3 X-ray diffractometer (XRD). The samples were ground into powder and loaded into the sample stage. The positions of the X-ray source, sample stage, and detector were adjusted to ensure optimal diffraction conditions. A copper target was selected as the X-ray source, with the tube voltage and current appropriately set. The diffraction angle was fixed at 20, and the scan range was set from 5\({}^{\circ}\) to 80\({}^{\circ}\). After configuring all parameters, the XRD scanning commenced. During the scanning process, X-rays passing through the sample generated diffraction peaks at specific angles, forming the XRD diffraction pattern shown in Figure 3. Quantitative analysis and phase identification of the sample were performed using dedicated data processing software, enabling the determination of the mineral composition of the Hipparion laterite. The experimental results are summarized in Table 3.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Soil Characteristics** & **Values** & **Test Methods** & **Standards** \\ \hline Natural moisture, \(\omega\) (\%) & 20.35 & Drying & GB/T 50123–2019 5.2 [71] \\ Density, \(\rho\) (g/cm\({}^{3}\)) & 2.06 & Ring knife & GB/T 50123–2019 6.2 [71] \\ Dry density, \(\rho_{d}\) (g/cm\({}^{3}\)) & 1.71 & Formula calculation & GB/T 50123–2019 6.2 [71] \\ Specific gravity, \(Gs\) & 2.71 & Heavyweight bottle & GB/T 50123–2019 7.2 [71] \\ Plastic limit, \(\omega_{\text{P}}\) (\%) & 28.28 & Combined determination of & GB/T 50123–2019 9.2 [71] \\ Liquid limit, \(\omega_{L}\) (\%) & 48.51 & liquid and plastic limit & GB/T 50123–2019 9.2 [71] \\ Classification of soil & Low-liquid-limit clay (CL) & Plasticity index and liquid limit & GB/T 50145-2007 4.0.8 [72] \\ \hline \end{tabular}
\end{table}
Table 1: Basic physical index parameters of Hipparion laterite.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Ca\({}^{+}\)** & **Mg\({}^{+}\)** & **Cl\({}^{-}\)** & **SO\({}_{4}^{2-}\)** & **HCO\({}_{3}^{-}\)** & **CO\({}_{3}^{2-}\)** & **K\({}^{+}\) + Na\({}^{+}\)** & **Total Soluble Salt** & **PH** \\ \hline mg/kg & 141 & 32 & 59 & 178 & 475 & 0 & 87 & 972 & 8.15 \\ 1/Zmmol/kg & 7.04 & 2.63 & 1.66 & 3.71 & 7.78 & 0 & 3.48 & & 8.15 \\ \hline \end{tabular}
\end{table}
Table 2: Corrosion detection content of Hipparion laterite.  
Figure 3: XRD pattern of mineral composition in Hipparion laterite.  
Particle size analysis was conducted on Hipparion laterite samples using a Bettersize 2600 laser particle size analyzer. Cumulative percentage content curves for different particle sizes were derived (Figure 4). Statistical analysis revealed the following particle size distribution: effective particle size D\({}_{10}\) = 1.175 \(\upmu\)m, median particle size D\({}_{30}\) = 3.866 \(\upmu\)m, control particle size D\({}_{60}\) = 9.598 \(\upmu\)m. The clay content (D \(\leq\) 5\(\upmu\)m) was 38.35%, the silt content (5 \(\upmu\)m \(\leq\) D \(\leq\) 75 \(\upmu\)m) was 58.26%, and the sand content (predominantly fine sand) (75 \(\upmu\)m \(\leq\) D \(\leq\) 250 \(\upmu\)m) was 3.39%. The calculated coefficient of inhomogeneity (Cu) is 8.169, and the coefficient of curvature (C\({}_{\rm c}\)) is 1.325, indicating that the Hipparion laterite sample is well graded.