Seafloor-Riser Interaction Model
Publication: International Journal of Geomechanics
Volume 9, Issue 3
Abstract
Fatigue stresses associated with extreme storms, vessel movements, and vortex-induced vibrations are critical to the performance of steel catenary risers. The critical location for fatigue damage often occurs within the touchdown zone, where cyclic interaction of the riser with the seabed occurs. Developing a model for seabed stiffness requires characterization of a number of complex nonlinear processes including trench formation, nonlinear soil stiffness, soil suction, and breakaway of the riser from the seafloor. The analytical framework utilized in this research considers the riser-seafloor interaction problem in terms of a pipe resting on a bed of springs, the stiffness characteristics of which are described by nonlinear load-deflection curves. The model allows for first penetration and uplift, as well as repenetration and small range motions within the bounding loop defined by extreme loading. The backbone curve is constructed from knowledge of the soil strength, the rate of strength increase with depth, trench width, and two additional parameters, while three parameters are necessary for the cyclic response.
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Acknowledgments
The writers would also like to acknowledge the support of Department of the Interior Minerals Management Service (Cooperative Agreement No. UNSPECIFIED35515), the Offshore Technology Research Center, and their colleagues at Texas A&M University.
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Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 9 • Issue 3 • May 2009
Pages: 133 - 141
Copyright
© 2009 ASCE.
History
Received: Sep 13, 2007
Accepted: Dec 8, 2008
Published in print: May 2009
Published online: May 15, 2009
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