Single Buoyancy Load to Trigger Lateral Buckles in Pipelines on a Soft Seabed.

For exposed subsea pipelines, lateral buckles are usually artificially triggered as an accommodation technique to release thermal expansion by providing temporary flotation with controlled spacing. With the given buoyancy load, the pipeline will be uplifted initially and will then buckle laterally under a certain thermally induced axial load, which is called the bifurcation load. Previous studies have analyzed this problem and modeled the uplifted pipeline as a fixed-fixed end beam, assuming the lateral seabed stiffness is infinite. However, the lateral seabed stiffness is usually low because the seabed is formed from soft soils. Using analytical methods, this paper investigates the buoyancy load required to trigger lateral buckles along a pipeline, considering a seabed with finite elastic stiffness, and provides suggestions for the buoyancy design with an elastic-plastic seabed model using an example of finite-element analysis. It was found that the seabed condition significantly influenced the flotation design. [ABSTRACT FROM AUTHOR]