# Safety Analysis and Condition Assessment of Corroded Energy Pipelines under Landslide Disasters
## 4 Results and Discussion
### Effect of Corrosion Location
Figure 13 shows a stress analysis contrasting the maximum stresses at corroded sites with those at non-corroded areas across various circumferential angles. For corrosion defects at positions of 0\({}^{\circ}\), 30\({}^{\circ}\), 60\({}^{\circ}\), 180\({}^{\circ}\), 210\({}^{\circ}\), 240\({}^{\circ}\), and 330\({}^{\circ}\), as the landslide displacement grows, the area of maximum stress transitions from the defect to around 105-120\({}^{\circ}\) on the slide-facing side. Initially, the weakening effect of the defect dominates. Still, as displacement increases, the load from the sliding soil becomes paramount, shifting the stress concentration from the defect toward the slide face until a potential failure occurs. When corrosion defects are located on or near the slide-facing side (90\({}^{\circ}\), 120\({}^{\circ}\), 150\({}^{\circ}\)), the stress at the defect remains consistently higher than in other orientations as the landslide displacement increases. This is primarily due to the combined effects of the defect and landslide, which collectively outweigh the impact of the landslide alone. Consequently, there is a pronounced stress concentration at the defect, leading to steadily increasing stress levels until yielding occurs as the displacement load grows. When corrosion defects are positioned on the back side of the slide, specifically at 270\({}^{\circ}\) and 300\({}^{\circ}\), the stress at the defect location increases with the growing landslide displacement. However, the stress in areas closer to the slide-facing side eventually surpasses the defect stress. This behavior results from the combined stress on the pipeline, induced by the increasing displacement and the defect on the non-slide facing side. When the landslide load becomes more incredible, the stress near the slide-facing side becomes the primary influence. Figure 14 shows the stress distribution for corrosion positions at 30\({}^{\circ}\), 90\({}^{\circ}\), 150\({}^{\circ}\), 210\({}^{\circ}\), 270\({}^{\circ}\), and 330\({}^{\circ}\) under a 0.8 m displacement and the corresponding limit displacements for each angle. In Figure 14a, the stress variation across different corrosion circumferential positions is prominent only at the defect, while it remains almost uniform elsewhere. Notably, when the corrosion is at 90\({}^{\circ}\), the stress reaches 558 MPa, indicating yielding, whereas at 210\({}^{\circ}\), the stress is at its lowest at 365 MPa, signifying a safe state. An interesting phenomenon is observed based on the stress distribution. For non-corroded pipelines, areas under low stress show significant stress shifts when corroded, while high-stress regions exhibit a minimal change when the defect occurs. In Figure 14b, the minimum limit displacement is 0.358 m when the corrosion is located at 120\({}^{\circ}\) on the pipeline. From 120\({}^{\circ}\) to 300\({}^{\circ}\), the limit displacement distribution gradually increases in a semi-heart shape. The maximum limit displacement is 0.806 m, which is 0.053 m higher than the pipeline without corrosion defects. When corrosion occurs in areas with higher stress on the slide-facing front, the hazard is more significant. However, when corrosion occurs in areas with higher stress on the slide-backing face, the hazard is reduced. The harm of landslides on the facing surface is more sig  
Figure 13: Comparison of maximum equivalent stress at corrosion and non-corrosion sites across different angular directions. back surface, and the displacement due to landslides plays a crucial role in determining the safety and integrity of the pipeline. Evaluating the effects of the axial corrosion location, the stress distribution pattern from the middle of the landslide to the non-landslide area was investigated. As shown in Figure 15, at a displacement of 0.8 m, the maximum stress occurs at the corrosion site when it is within 6 m from the landslide center. Beyond this axial distance, the maximum stress shifts back to the center of the landslide, surpassing the stress at the defect.