Approximate Accounting for Corrosion in Estimation of Strain Demand on Buried Pipelines Subject to Ground Displacements

AbstractBuried energy pipelines traversing long distances are susceptible to permanent ground displacements (PGDs), wherein, high soil restraints can induce potentially unacceptable strains in the pipelines. This concern has motivated practitioners to design pipelines using strain-based approaches, preferably over stress-based approaches. Analytical and numerical approaches are available to predict strain demand on buried pipelines due to permanent ground displacements, which forms the key input to strain-based design approach; computations are usually made assuming intact conditions although buried pipelines could possess segments with metal loss due to corrosion. Vulnerability of such corroded pipelines to permanent ground displacements make this a multi-hazard problem. The present study aims at exploring and quantifying the response of pipelines under both corrosion as well as PGD hazard and computing the resulting strain demand to pipelines. Several cases of FE analysis are performed using ABAQUS software, considering the cases of both intact and corroded pipelines subjected to spatially varying and abrupt ground displacement PGD profile. Corrosion metal loss for the pipe is accounted assuming equivalent reduced cross section. Using initial findings from this work, approximate factors are proposed to modify the strain capacity against ground displacements derived for uncorroded buried pipelines.KeywordsStrain demandBuried pipelinesPermanent ground displacementsCorrosionFE model