# Analysis of Slope Stability in Ion-Adsorption Rare Earth Mine Under In Situ Leaching Condition
## 3 Results and Discussion
### Analysis of Plastic Zone and Displacement Characteristics in Rare Earth Mine Slopes  
The distribution of the plastic zone on the slope during the leaching and push-water operation is shown in Figures 10 and 11. It should be noted that the yellow areas in Figures 10 and 11 denote the plastic zones. As shown in Figure 11, the result indicates that plastic zones develop at the top of the slope. As leaching progresses, large plastic zones emerge in the middle to upper parts of the slope and at the interface between the leaching agent injection wells and the ore-hosting horizon of the fully weathered granite layer. This can lead to the formation of tension cracks at the top of the slope. This phenomenon occurs because leaching starts from the top of the slope, allowing the leaching solution to infiltrate the mine through gravity and soil matrix suction. This results in a rapid increase in saturation and soil unit weight. The top of the slope is the first to experience the impact of permeate volume strength, causing soil particles to deform and displace along the infiltration path. In addition, the plastic zone within the fully weathered granite layer continues to expand with the leaching time. The leaching solution infiltrates along the slope to deformation. Because each layer's interface, particularly between fully weathered and semi-weathered layers, represents a weak point. The distribution of the plastic zone on the slope during the leaching and push-water operation is shown in Figures 10 and 11. It should be noted that the yellow areas in Figures 10 and 11 denote the plastic zones. As shown in Figure 11, the result indicates that plastic zones develop at the top of the slope. As leaching progresses, large plastic zones emerge in the middle to upper parts of the slope and at the interface between the leaching agent injection wells and the ore-hosting horizon of the fully weathered granite layer. This can lead to the formation of tension cracks at the top of the slope. This phenomenon occurs because leaching starts from the top of the slope, allowing the leaching solution to infiltrate the mine through gravity and soil matrix suction. This results in a rapid increase in saturation and soil unit weight. The top of the slope is the first to experience the impact of permeate volume strength, causing soil particles to deform and displace along the infiltration path. In addition, the plastic zone within the fully weathered granite layer continues to expand with the leaching time. The leaching solution infiltrates along the slope towards the bottom, resulting in substantial permeate volume strength and increasing soil  
Figure 9: Distribution of (**a**) maximum effective stress and (**b**) minimum effective stress after 15 days of leaching. deformation. Because each layer's interface, particularly between fully weathered and semi-weathered layers, represents a weak point. This causes the plastic zone to extend downward from the top along the slope, merging with the plastic zone at the interface between the fully weathered and strongly weathered granite layers. Additionally, the localized plastic zones developed at the bottom of the slope in the later stages. Figure 12 shows the distribution of displacement after 15 days of leaching, it visually depicts the distribution and magnitude of slope displacement. As the leaching solution continues to be injected, it infiltrates from the injection wells through the topsoil to the fully weathered ore-hosting layer and even into the less permeable bedrock. During this infiltration process, the displacement changes in the slope are most pronounced in the middle to upper parts, decreasing gradually from the vertical slope inward. This suggests that tensile cracks may form in the middle to upper parts of the slope. Additionally, the ongoing leaching increases the downward sliding force on the upper soil mass, ultimately leading to the slope sliding outward and potentially triggering geological hazards.