The thermal expansion of heated pipelines buried in soft clay will develop a very complex soil-pipeline interaction phenomenon, inducing possibly-unstable buckles which may be supported by the passive soil reaction. These unstable buckles will develop as a non-linear inelastic regime, and the pipeline can jump from lateral or vertical displacements of few centimetres to one of metres. Once these finite displacements have developed, there is the possibility of local pipeline buckling, causing the pipeline to rupture and an oil spill as a consequence. This article presents a comprehensive description of the results obtained during the analysis of a rupture of a buried heated pipeline in Guanabara Bay, Rio de Janeiro, in Brazil. A very sophisticated procedure, including simulation of the thermal-mechanical interactions between the soil and the pipeline structure, was developed. Computer modelling was carried out using the finite-element technique, considering the soil and the pipeline's non-linear material behaviour and finite displacements. A cyclic thermo-mechanical soil-pipeline structure interaction model was the challenging aspect of the simulation, in order to explain the trigger mechanism of the "snap-through" behaviour of the heated pipeline which was responsible for the rupture of the line in Guanabara Bay. In order to overcome this challenging and destructive behaviour, a special pipeline with a 'zig-zag' geometry was developed, designed to accommodate thermal elongations and avoid lateral or vertical buckling.
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