# Safety Analysis and Condition Assessment of Corroded Energy Pipelines under Landslide Disasters
## 6 Conclusions  
This study employed numerical simulations to conduct a safety analysis of corroded pipelines under landslide disasters. Effects of critical parameters, including corrosion depth, corrosion length, and landslide displacement, are examined. The main contributions of this work involve (1) a correlation between the corrosion location and the maximum stress of pipelines is explored; and (2) a novel prediction equation for the maximum stress of corroded pipelines under landslides is developed, which considers not only the pipeline-soil interaction but also the existing corrosion dimensions and current landslide displacement. The conclusions of this work are as follows:  
* Under landslide conditions, the maximum stress of the pipeline increases with the growth of corrosion length or depth, albeit marginally. The order of the influence of each factor on the pipeline is landslide displacement > defect depth > defect length. * As displacement increases, the initial single-peak axial stress gradually transforms into a tri-peak stress profile (edge-center-edge) due to the combined effects of the landslide-induced soil thrust and soil shear at the edge. The angle facing the slide becomes the most vulnerable part of the pipeline, warranting close attention in engineering projects. * There is an interplay between the stress concentration and the increasing corroded area when the corrosion defect is small in depth and length. This interplay can lead to a short-term increase in the limited landslide displacement, followed by a gradual decrease. * For the defect at different circumferential positions in the pipeline, the maximum stress location alternates between the slide-facing side and the defect. When the defect is near the slide-facing angle, this side becomes the most critical, when situated between the slide-facing and slide-backing sides, the maximum stress remains on the slide-facing side, and when the defect is located near or at the slide-backing side, the stress at the defect exceeds that of the slide-facing side. * When the defect is not central within the landslide, the stress at the defect exceeds that at the landslide center. Yet, when the defect shifts a certain distance from the center, the landslide's central influence prevails, making the defect location the most hazardous \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Model** & **R** & **R2** & **MSE** & **F-Test** \\ \hline Test value & 0.9943 & 0.9732 & 4.7977 & 49.7363 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Model verification. point of maximum stress. Moreover, its stress decreases as the defect distance from the center increases, but in edge areas, shearing effects cause some increases in stress. The limitation of this work lies in its omission of an in-depth exploration into the formation mechanism of corrosion. The corrosion defect was modeled as a rectangular shape, assuming uniform thinning of local wall thickness. Additionally, this study did not account for the possibility of multiple corrosion defects occurring in pipelines. Future directions involve addressing the condition assessment of parallel corroded pipelines under landslide conditions, which can be combined with a finite element simulation, theoretical analysis, and reliability assessment, with a focus on addressing the coupled safety issues of parallel pipelines under landslide conditions. Conceptualization, S.L. and W.L. ; Methodology, P.Z. and T.X. ; Software, S.L. and Y.L. ; Validation, W.L. and T.X. ; Investigation, Y.H. ; Data curation, Y.L. ; Writing--original draft preparation, W.L. ; Writing--review and editing, P.Z., S.L. and Y.H. ; Supervision, P.Z. All authors have read and agreed to the published version of the manuscript. This work was supported by National Natural Science Foundation of China, grant number 50974105; Special Research Fund for Doctoral Programs in Universities, grant number 20105121110003; Major Consulting Research Project of the Chinese Academy of Engineering, grant number 2011-ZD-20. Not applicable.