Numerical Simulation of Buried Steel Pipelines under Strike-Slip FaultDisplacements

The paper examines the structural response of buried butt-welded steel pipelines, crossing active strike-slip tectonic faults, which are vertical and perpendicular to the pipeline axis. The interacting soil-pipeline system is simulated with finite elements, accounting for large strains and displacements, nonlinear material behaviour, as well as for contact and friction on the soil-pipe interface. Steel pipelines of various diameter-to-thickness ratios, and typical steel material for pipeline applications (API 5L grade X65) are considered. The paper investigates the effects of various soil and pipeline parameters on the mechanical response of the pipeline, with emphasis on pipe wall "kinking" or fracture. The effects of cohesive and non-cohesive soils are also investigated. Furthermore, the influence of internal pressure on the structural response of the steel pipeline is examined. The numerical results are aimed at determining the fault displacement at which the pipeline failure occurs, they are presented in a graphical form showing the critical fault displacement, the corresponding critical strain versus the pipe diameter-to-thickness ratio, and can be used for efficient pipeline design against significant ground-induced deformations due to active strike-slip faults.