Numerical framework for risk assessment of buried natural gas pipelines subjected to landslide-induced deformations due to rainfall infiltration: The Miscano landslide case

Natural gas pipeline systems constitute an indispensable type of infrastructure due to their vital function in transporting essential energy resources. Given their widespread nature, pipeline systems may cross unstable slopes, thereby exposing them to potential deformations caused by slope movements. Enhancing the resilience of these systems against slope displacements requires proper assessment of the displacements magnitude, as well as of the vulnerability of the pipelines affected. This study presents a comprehensive numerical framework for assessing the risk of buried natural gas pipelines subjected to axial deformation, due to landslide phenomena induced by rainfall infiltration. The Miscano landslide is examined as a case study. The proposed framework follows an uncoupled approach, consisting of two numerical models and an Event Tree Analysis (ETA). The first numerical model assesses landslide displacements induced by rainfall infiltration, whereas the second model analyzes the soil-pipeline interaction phenomena to assess the pipeline's vulnerability through analytical fragility functions, derived from statistical analysis. Consequences of a potential failure are assessed based on an Event Tree Analysis (ETA) approach. The results confirm the significant role of pipeline dimensions and steel grade in reducing vulnerability of natural gas pipeline networks. Consequences assessment show that flash fire caused by delayed local ignition is the most probable event to have as a result of a buried natural gas pipeline failure caused by landslide axial displacements. Based on the results of the study, a probability-based buried pipeline inspection and maintenance framework is finally presented, enhancing the applicability of the proposed framework.