## 4 Results  
### Characteristics of Landslide Deformation  
Multiperiod imagery of the study area was acquired using field geological surveys. Beginning with the observation of surface cracks in July 2022 and extending to September, a total of five landslides occurred on the eastern pit slope. All these landslides slide from east to west, with an approximate orthogonal projection area of 4.66 \(\times\) 10\({}^{4}\) m\({}^{2}\). Among them, three landslides on the south side of the eastern pit slope are centrally developed and relatively large in size. Detailed parameters for each landslide can be found in Table 2, and their distribution characteristics are illustrated in Figure 12.  
Figure 11: Numerical simulation process based on Rhinoceros software and FLAC3D software. As of March 2023, the southern pit's excavation had reached an elevation of 1548 m, resulting in the formation of a high and steep slope measuring approximately 83 m in height. As shown in Figure 13, this increase in mining depth has resulted in a significant change in overall slope angle, from 25\({}^{\circ}\) in September 2022 to 33\({}^{\circ}\). As the height of the eastern mining pit slope increases, stress concentration zones are generated due to stress redistribution near the slope surface. As shown in Figure 14, a total of 936 tensile fissures were developed in the tensile stress zone near the top of the eastern pit slope on the south side of the mining pit. Notably, the fissures at the trailing edge of the landslide II-1 exhibited more extensive development, causing slight misalignment at the upper platform edge and noticeable shear-induced bulging deformation in the lower \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Landslide**} & \multirow{2}{*}{**Length/m**} & \multirow{2}{*}{**Width/m**} & **Relative Height** & \multirow{2}{*}{**Terrain Slope/\({}^{\circ}\)**} & **Sliding Direction/\({}^{\circ}\)** & **Area/m\({}^{2}\)** \\  & & & **Difference/m** & & & \\ \hline I-1 & 45 & 48 & 26 & 30 & 255 & \(0.20\times 10^{4}\) \\ I-2 & 107 & 117 & 43 & 28 & 237 & \(1.12\times 10^{4}\) \\ I-3 & 35 & 58 & 17 & 31 & 219 & \(0.16\times 10^{4}\) \\ I-4 & 129 & 143 & 59 & 28 & 262 & \(1.71\times 10^{4}\) \\ I-5 & 116 & 135 & 49 & 26 & 263 & \(1.47\times 10^{4}\) \\ \hline \end{tabular}
\end{table} 
Table 2: Landslide parameters in the Wolong open-pit coal mine. Figure 12: Distribution map of landslide hazards (September 2022). Figure 13: Topographic line of the Wolong open-pit coal mine from September 2022 to March 2023.  
portion. The orthographic projection area of the deformed bodies of landslides II-1 and II-2 is approximately 7.84 \(\times\) 10\({}^{4}\) m\({}^{2}\), and the deformation direction is approximately 263\({}^{\circ}\) (Figure 14). The strata in the landslide deformation zone exhibited a gradual decrease in dip, shifting from 85\({}^{\circ}\) at the bottom to 70\({}^{\circ}\) at the top. Additionally, the front edges of mining benches displayed signs of stratigraphic inversion, which is characterized by distinct features of flexural toppling failure (Figures 14 and 15). Due to continuous creep deformation, the central region of the pit slope has experienced severe deformation, leading to the development of small, shallow landslides. Tensile fissures, extending tens of meters upward to the slope's peak, exhibit noticeable characteristics of inversion, particularly on the stepped-slope surface, as depicted in Figure 15.  
As illustrated in Figure 10, the window sampling method was employed to collect the fracture information within the exposed lithology of the pit slope. Then, utilizing  
Figure 14: Deformation development characteristics of the eastern pit slope (March 2023). Figure 15: Deformation characteristics of the pit slope: (**a**) Shallow landslide; (**b,c**) Tension fissure in the mining benches.