Βehavior of underground energy pipelines under permanent ground displacements

Abstract

The seismic performance of oil and natural gas steel pipelines embedded in earth slopes presents great uncertainty related both to the earthquake shaking characteristics and to the natural heterogeneity of geomaterials. Slope movements and landslides in general constitute a significant risk to pipelines because they can cause permanent deformations and rupture, resulting in spills, environmental problems, and long periods of outage. Moreover, significant risks for underground pipeline integrity may be caused by permanent ground displacements from tectonic fault action, lateral spreading of liquefied soils, where soil can move for a few meters and impose major deformation on the section of pipeline passing through the affected area. Similar risks appear also in the case of pipes embedded in a liquefiable soil layer passing below a river or ground aquifer. In all these cases, the pipe may be subjected to bending resulting to significant compression, with a high risk of local buckling, large plastic deformation and wall rupture. The magnitude of the imposed ground movement may depend significantly on the spatial variability of the soil properties in a zone along the path of the pipeline system. Also, the seismic response of a slope earth with embedded pipeline is investigated. The results compared with a similar slope with spatial variability of soil properties demonstrate that the influence of ground movement imposed on the embedded pipeline is very important and should be accounted for the evaluation of its seismic safety. The study is based on numerical modelling of the soil–pipeline systems, by considering the soil–pipe interaction during seismic shaking. The aim of this study is the investigation of the behaviour of underground energy pipelines under permanent ground displacements. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.