On the Calibration of Coefficients of Friction for Pipeline-Seabed Interaction

Abstract

Subsea pipelines placed on the seabed can buckle due to thermal and mechanical loads. This buckling, and the associated pipe walking phenomena, can lead to large stresses in the pipe sections and at the pipe end attachments. These high stresses need to be accounted for in pipeline design. An accurate simulation of pipeline buckling for design purposes requires a rational representation of the nonlinear large deformations of the underlying soil, which entails a large 3D problem to be solved with repeated remeshing in the Lagrangian setting. However, it is possible to reduce this effort and forgo the direct modeling of the underlying soil by modeling the pipe as a beam, the seabed as a surface, and the resistance offered by the soil to the pipe through an appropriate contact interaction behavior between the pipe and the seabed. This contact interaction behavior can be expressed through variable coefficients of friction between the pipeline and the seabed. In this paper the Coupled Eulerian-Lagrangian technique is used to evaluate the resistance offered by the plastic soil to the pipeline; the resistance data are then used to calibrate these coefficients of friction, which are in turn used in an implicit dynamic analysis for simulating the buckling deformations of a representative pipeline, modeled as a beam, in contact with the seabed, which is modeled as a surface.