SIIBED: Numerical Modeling of Subsea Pipelines and Cables in Ice Prone Region

Abstract

The objective of this paper is to incorporate the outcomes of laboratory and physical testing carried out under the SIIBED program in order to develop, calibrate and validate a design tool for assessment of risk to subsea infrastructure due to ice keel interaction with pipelines, flexible flowlines, and electrical cables. This tool could then also be used to investigate load transfer to other subsea structures and facilities. A numerical modeling procedure is developed using the finite element analysis software Abaqus where the large deformation process of iceberg-pipe-soil interaction can be accommodated using the Coupled Eulerian Lagrangian (CEL) technique. The complexity of the ice-pipe-soil interaction is captured by appropriate and varied contact strategies in different areas of the model. Details of the model are discussed, including advancements of soil behavior and flexible flowline mechanical response, where it is desirable for the design tool to be optimized for computational efficiency while retaining reliable predictions of response. Case studies are presented for thick walled pipeline, flexible flowlines and electrical cables. Typically, the ice is modeled as a rigid body with unlimited strength. Limiting ice interaction forces, via pressure, is shown to have an effect on the displaced shape of the pipeline and flexible. Including radial compliance of the electrical cable is also shown to have an effect. With mesh refinement and retaining sufficient complexity in key areas, the complex model can be analyzed with a reasonable amount of computational cost. Advancements in the modeling of the ice feature strength limits are highlighted as well as application of large deformation modeling of electrical cables, which is atypical.