Lateral resistance of "rigid" pipelines and cables on rocky seabeds

Terry Griffiths, David J. White, Scott Draper, Adam Leighton, Liang Cheng, Hongwei An, Antonino Fogliani

Research output: Contribution to journalArticle

329 Downloads (Pure)

Abstract

Accurate assessment of lateral resistance is critical to ensure the on-bottom stability and integrity of subsea pipelines and cables in the oil-gas and marine renewable energy industries. However, on rocky seabeds recommended practices provide limited recommendations on pipe-seabed interaction, suggesting only a single value for the friction coefficient of 0.6. This paper reports on a programme of physical experiments and theoretical modelling investigating the lateral resistance of pipes on rocky seabeds. It is shown that the peak and mean effective friction can significantly exceed the interface (or Coulomb) friction coefficient when the pipe diameter (D) is similar to the median rock diameter (d(n50)). Only when the pipe diameter becomes large compared to the rock size does the mean effective friction approach the interface friction. The effective friction coefficient was found to vary with variability in rock size and shape, as well as the length of pipe relative to median rock diameter. Each of these findings is reproduced well using the theoretical model. Collectively, the results demonstrate that the effective lateral friction coefficient may be higher than 0.6 for mean friction, and significantly higher for peak friction. This implies that inaccuracy may exist in current design, which may be rectified using the theoretical model.

Original languageEnglish
Pages (from-to)823-839
Number of pages17
JournalCanadian Geotechnical Journal
Volume56
Issue number6
DOIs
Publication statusPublished - Jun 2019

Cite this