An analytical procedure for modelling pipeline-landslide interaction in gas pipelines

Abstract Landslide occurrence is a major consequence of seismic activity in uphill ground conditions. There effects range from minor damage to severe malfunctioning of local infrastructure. Particularly for transport systems such as underground gas transmission pipelines, the nature of landslide phenomenon is usually catastrophic, thereby necessitating a detailed design analysis for ensuring structural integrity. Numerous research studies have addressed these specific considerations, facilitated substantially by the advent of numerical software simulation. However, relevance of theoretical analysis and their application is still considered significant. This research study aims to determine the limiting axial strains of an underground gas pipeline subjected to longitudinal landslide movement. A novel mathematical formulation is first developed, giving due consideration to the pipeline-soil interaction, internal pressure, weight and temperature loads. Numerical simulation study through COMSOL Multiphysics software is then conducted for the same given conditions. Percentage error of around 6% was observed between the results obtained from both approaches. The proposed analytical methodology was further validated through sensitivity analysis involving slope angle variation. For different slope angles, percentage error between software and analytically computed results varied between 4% and 6%. Effects of changes in pipeline material, soil cohesive strengths and temperature gradient on underlying strains and loads contribution profile were also investigated through the sensitivity analysis study. For the achieved results, compliance with American Lifeline Alliance code was ensured and achieved for both tensile and compressive strain domains.