## 2 Materials  
The Lijiazu Landslide is in Shijiang Village, Huju Town, Chaling County, Zhuzhou City, Hunan Province, China. The main landslide is on the east bank of the Mishui River, about 200 m from the river. Geologically, it is on the southwestern edge of the Chayong Basin, with the main fault being the Jiubujiang Fault, which runs NE-SW (Figure 1). In the study area, there is no significant recent tectonic activity, indicating that it belongs to a relatively stable tectonic block. According to the local geological map (Figure 1), the main exposed geological formations in the study area consist of the Devonian, Carboniferous, Jurassic, and Quaternary periods. The exposed geological formation of the landslide area is characterized by the Carboniferous Malanbian Formation. The main sliding direction of the landslide is 332\({}^{\circ}\), and it exhibits an irregular shape overall. The slope gradient ranges from 20\({}^{\circ}\) to 35\({}^{\circ}\), with an average gradient of 28\({}^{\circ}\). The main body of the landslide has a length of approximately 100 m and a width of around 160 m, categorizing it as a small-scale landslide (Figure 2). On both sides of the landslide, the boundaries are marked by cracks, and these boundaries align with the transition from gentle to steep slopes on the natural hillside. The landslide front edge is located behind the residential house retaining wall, and due to the continuous development of the landslide, the retaining wall has experienced cracking and expansion (Figure 3). Based on the data consulted, the annual precipitation in the research area is around 1400 mm. The wet season spans from March to August, with monthly rainfall exceeding 100 mm each month. The rainy season, from April to June, experiences an average monthly precipitation of approximately 200 mm. In order to analyze comprehensively the landslide and investigate the geological characteristics of the landslide strata, a total of six boreholes were deployed at the landslide site (Figure 4). Based on the findings from drilling and geological investigations, it can be determined that the landslide cover material is mainly composed of fine-grained clay and gravelly soil. The underlying bedrock consists of Carboniferous lower Malanbian Formation, which is composed of siltstone, sandy shale, and limestone (Tables 1 and 2). Borehole data reveal that the sliding surface is situated within the sandy shale stratum. Physical tests indicate that the local geological strata are relatively fragmented, with poor physico-mechanical properties. Figure 1: Geological map of the study area. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample ID** & **MC \%** & **Sp. Gravity** & **Liquid Limit \%** & **Plastic Limit \%** & **Plasticity Index** & **DD (g/cm\({}^{3}\))** & **VR** \\ \hline
1 & 22.35 & 2.72 & 35.65 & 21.55 & 14.1 & 1.56 & 0.75 \\
2 & 24.8 & 2.72 & 37.5 & 22.6 & 14.9 & 1.55 & 0.76 \\
3 & 23.2 & 2.71 & 33.1 & 21.0 & 12.1 & 1.57 & 0.73 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Physical parameters of soil mass in landslide area. Figure 3: Landslide deformation signs: (**a**) cracks in the retaining wall at the front edge of the landslide; (**b**) landslide trailing edge crack. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample ID** & **Test** & **Number** & **Average** & **Maximum** & **Minimum** \\  & & & **Value** & **Value** & **Value** \\ \hline \multirow{3}{*}{4} & Uniaxial compressive strength (MPa) & 4 & 62.31 & 77.60 & 45.10 \\  & Shear strength & Internal friction angle (\(\Phi\)) & 4 & 42.18 & 44.2 & 41.2 \\ \cline{1-1}  & Cohesive force (MPa) & 4 & 6.02 & 7.25 & 6.17 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical and mechanical parameters of limestone. Figure 2: Map of landslide location. Yellow dashed circle: Landslide location in satellite images. Red: dashed circle: Drone aerial photography of landslide location. Red spot: study area.