Development of Landslide Fragility Functions for Natural Gas Transmission Pipelines

Abstract

Natural gas transmission pipelines are at risk of failure when they traverse potential landslide regions, leading to significant service disruptions and environmental impacts. This paper presents the results of an analytical study on the vulnerability of typical natural gas transmission pipelines when they are subjected to landslide-induced ground displacements. Pipeline vulnerability was evaluated for four pipe diameters under different internal pressures and various ground displacement profiles. The effects of pipe wall thickness and steel grade on vulnerability were also evaluated. The finite-element method was used to model the pipelines and the surrounding soils. Nonlinear static analyses were carried out to evaluate the response of the pipelines under landslide-induced ground displacements. Based on results of the analyses, landslide fragility functions were developed for the pipelines at the pressure integrity (PI) limit state. The results of this study indicate that pipeline vulnerability decreases with increasing pipe diameter but increases with increasing landslide width up to a threshold width where the effect becomes negligible. Additionally, internal pressure is found to have no significant effect on the vulnerability of various pipelines at the PI limit state. The results also show that the risk of pipeline failure can be reduced significantly by increasing pipe wall thickness and using a higher grade of steel material in landslide regions.