Lateral Thermal Buckling of Pipelines on the Sea Bed

Abstract

Lateral buckling can occur in a submarine pipeline laid (without trenching) on the seabed, when the oil temperature rises. Motion of the (elastic) pipe relative to the sea bed is resisted by friction. The initial buckling is a localization phenomenon, and the first buckle lobes to form grow in amplitude most rapidly as the temperature increases. But as the temperature continues to rise, these early buckles cease growing, and growth is transferred to adjacent, newly formed lobes. The lobes first formed thus eventually become “extinct.” We investigate these phenomena by means of a small-scale physical model and by computer simulation. The results of many computer runs can be condensed into a few universal curves by the use of suitable dimensionless groups. Simple formulas emerge for the amplitude and wavelength of the “extinct” lobes, and for the maximum bending strain experienced by the pipeline, as a function of temperature.