Soil-pipe interaction models for simulating the mechanical response of buried steel pipelines crossing active faults

Abstract

In geohazard areas, buried pipelines are subjected to permanent ground deformations, which constitute major threats for buried pipelines. Geohazards include seismic fault movements, liquefactioninduced lateral spreading and slope instability and the corresponding deformation induce severe strains in the pipeline, well beyond the elastic regime of the pipe material. Calculation of those strains is necessary for assessing pipeline integrity, and requires the development of numerical models that account for soil-pipe interaction. In the present paper, the performance of buried steel pipelines under severe ground-induced actions is investigated. In the first part of the paper, soil-pipe interaction is investigated with respect to pipe movements in axial and transversal direction using a rigorous finite element model. The model uses shell elements for the pipe and solid elements for the soil, and is calibrated through full-scale experimental testing, conducted at CSM facilities, Sardinia, Italy and other experimental tests of the literature. The comparison between the experimental results and the rigorous model offers valuable information for the key parameters governing soil-pipe interaction. In the second part of this paper, using the rigorous finite element model, calibrated through the above experiments, an analysis of pipeline response at fault crossing areas is conducted. The numerical results are compared with full-scale experimental results, also performed at CSM facilities and offer significant intuition on the behavior of buried pipelines subjected to permanent ground deformations. The present work is aimed at proposing complementary provisions in existing guidelines for buried pipeline design in geohazard areas. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).