Analytical Prediction of Pipeline Behaviors in -Lay on Plastic Seabed
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 138, Issue 2
Abstract
-lay is widely accepted as a favorable method for deepwater pipeline installation. The configuration and internal force of the pipeline during the laying process are key factors for its safety, and the embedment induced during pipeline installation plays an important role for pipeline stability in service. Traditionally, the seabed in the analysis of -lay is assumed to be elastic, whereas deepwater deposits are usually very soft, exhibiting low strength and obvious plasticity. This paper presents an analytical model for pipelaying on plastic seabed. This model simplifies the pipeline as the combination of four segments: a natural catenary in water, a boundary-layer segment, a beam on the seabed (touchdown zone) where the soil deforms plastically, and a freely laid horizontal segment. The comparison with a traditional elastic-seabed model reveals that both models have similar pipeline configurations, although the elastic-seabed model slightly underestimates the maximum bending moment. In contrast, the pipeline embedment depths in the two models differ with deeper ultimate penetration predicted in the plastic-seabed model.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors would like to acknowledge the support of Grant No. UNSPECIFIED51079128 from the National Natural Science Foundation of China and Grant No. NNSFCR1100093 from the Excellent Youth Foundation of Zhejiang Scientific Commitee, China.
References
Aubeny, C. P., Shi, H., and Murff, J. D. (2005). “Collapse loads for a cylinder embedded in trench in cohesive soil.” Int. J. Geomech., 5, 320–325.
Aubeny, C. P., Biscontin, G., and Zhang, J. (2006). “Seafloor interaction with steel catenary risers.” Offshore Technology Research Center Final Report, Texas A&M Univ., College Station, TX, 1–27.
Brando, P., and Sebastiani, G. (1971). “Determination of sealines elastic curves and stresses to be expected during laying operation.” Proc., Offshore Technology Conf., OnePetro, OTC 1354.
Bridge, C., and Laver, K. (2004). “Steel catenary riser touchdown point vertical interaction models.” Proc., Offshore Technology Conf., Houston, TX, OTC 16628.
Callegari, M., Carini, C. B., Lenci, S., Torselletti, E., and Vitali, L.(2003). “Dynamic models of marine pipelines for installation in deep and ultra-deep waters: Analytical and numerical approaches.” Proc., 16th AIMETA Congress of Theoretical and Applied Mechanics, Italian Association of Theoretical and Applied Mechanics, Milano, Italy, 9–12.
Chai, Y. T., and Varyani, K. S. (2006). “An absolute coordinate formulation for three-dimensional flexible pipe analysis.” Ocean Eng., 33(1), 23–58.
Cheuk, C. Y., White, D. J., and Dingle, H. R. C. (2008). “Upper-bound plasticity analysis of a partially embedded pipe under combined vertical and horizontal loading.” Soils Found., 48(1), 133–140.
Croll, J. G. A. (2000). “Bending boundary layers in tensioned cables and rods.” Appl. Ocean Res., 22(4), 241–253.
Dixon, D. A., and Rultledge, D. R. (1968). “Stiffened catenary calculation in pipeline laying problem.” J. Eng. Ind., 90B(1), 153–160.
Guarracino, F., and Mallardo, V. (1999). “A refined analytical analysis of submerged pipelines in seabed laying.” Appl. Ocean Res., 21(6), 281–293.
Hodder, M. S., and Cassidy, M. J. (2010). “A plasticity model for predicting the vertical and lateral behavior of pipelines in clay soils.” Geotechnique, 60(4), 247–263.
Lenci, S., and Callegari, M. (2005). “Simple analytical models for the -lay problem.” Acta Mech., 178(1–2), 23–39.
McDonald, D. N., Sullivan, D. J., and Chol, S. (1998). “The next generation -lay system.” International Petroleum Conf and Exhihibition of Mexico, Society of Petroleum Engineers, Villahermosa, Mexico.
Merifield, R., White, D. J., and Randolph, M. F. (2008). “The ultimate undrained resistance of partially embedded pipelines.” Geotechnique, 58(6), 461–470.
Murff, J. D., Wanger, D. A., and Randolph, M. F. (1989). “Pipe penetration in cohesive soil.” Geotechnique, 39(2), 213–229.
Palmer, A. C., Hutchinson, G., and Ells, W. J. (1974). “Configuration of submarine pipelines during laying operations.” J. Eng. Ind., 96, 1112–1118.
Palmer, A. C. (2008). “Touchdown indentation of the seabed.” Appl. Ocean Res., 30(3), 235–238.
Plunkett, R. (1967). “Static bending stresses in catenaries and drill strings.” J. Eng. Ind., 89(1), 31–36.
Powers, J. T., and Finn, L. D. (1969). “Stress analysis of offshore pipelines during installation.” Proc., Offshore Technology Conf., Houston, TX, OTC 1071.
Randolph, M. F., and White, D. J. (2008). “Upper-bound yield envelops for pipelines at shallow embedment in clay.” Geotechnique, 58(4), 297–301.
Randolph, M. F., and Quiggin, P. (2009). “Non-linear hysteretic seabed model for catenary pipeline contact.” ASME, Honolulu, HI, OMAE2009-79259.
Savik, S., Giertsen, F., and Berntsen, V. (2004). “Advances in design and installation analysis of pipelines in congested areas with rough seabed topography.” Proc., 23rd Int. Conf. on Offshore Mechanics and Arctic Engineering, ASME, Vancouver, Canada, OMAE2004-51344.
Seyed, F. B. (1992). “Mathematics of flexible risers including pressure and internal flow effects.” Mar. Struct., 5(2–3), 121–150.
Steward, D. P., and Randolph, M. F. (1994). “-bar penetration testing in soft clay.” J. Geotech. Eng., 120(12), 2230–2235.
You, J., Biscontin, G., and Aubeny, C. P. (2008). “Seafloor interaction with steel catenary risers.” Proc., 8th Int. Offshore and Polar Engineering Conf., International Society of Offshore and Polar Engineers, Mountain View, CA.
Information & Authors
Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 138 • Issue 2 • March 2012
Pages: 77 - 85
Copyright
© 2012 American Society of Civil Engineers.
History
Received: Jul 2, 2010
Accepted: Jun 16, 2011
Published online: Jun 18, 2011
Published in print: Mar 1, 2012
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.