Numerical Study of Mobilized Friction along Embedded Catenary Mooring Chains
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 145, Issue 10
Abstract
Understanding the soil resistance along an embedded anchor chain is imperative for efficient and economic design of an overall mooring system as it determines the magnitude and direction of the load at the padeye of the anchor. The tensioning process of an embedded chain for catenary moorings was modeled using a coupled Eulerian–Lagrangian (CEL) finite-element approach simulating the large deformations of the chain as it cuts through the soil to form an inverse catenary. The analyses reveal that the configuration of the embedded chain and the relationship between tension and chain angle at the padeye show excellent agreement with previously published analytical predictions. However, the ratio of the tension at the padeye to that at the mudline obtained from CEL is significantly higher than the theoretical values, mainly due to partial mobilization of the frictional soil resistance along the length of the chain. The CEL results indicate that the partial mobilization is a result of the combined-loading effect during failure of the soil around the embedded chain as it cuts through the seabed, in contrast with the conventional assumption that the ultimate frictional and normal soil resistances are mobilized simultaneously. A new design approach is proposed for calculating the local equivalent coefficient of friction based on the yield locus for a deeply embedded chain and the normality rule.
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Acknowledgments
This work forms part of the activities of the Centre for Offshore Foundation Systems. Established in 1997 under the Australian Research Council’s Special Research Centres Program and currently supported as a node of the Australian Research Council’s Centre of Excellence for Geotechnical Science and Engineering (ARC Grant No. CE110001009), and through the Fugro Chair in Geotechnics, the Lloyd’s Register Foundation Chair and Centre of Excellence in Offshore Foundations, and the Shell EMI Chair in Offshore Engineering. The first author is supported by an Australian Government Research Training Program Scholarship and a Fugro PhD Scholarship; the second author is supported by the National Natural Science Foundation of China (51890915); and the fifth author is supported as the Fugro Chair in Geotechnics. All support is gratefully acknowledged.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 145 • Issue 10 • October 2019
Copyright
©2019 American Society of Civil Engineers.
History
Received: Nov 17, 2018
Accepted: Jun 2, 2019
Published online: Jul 30, 2019
Published in print: Oct 1, 2019
Discussion open until: Dec 30, 2019
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