Mechanics of Drag Embedment Anchors in a Soft Seabed
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 136, Issue 1
Abstract
This paper presents an analysis of the load capacity and trajectory of a drag embedment anchor in a soft seabed. Anchor capacity relationships are developed for an idealized anchor comprising a rectangular fluke and a cylindrical shank. Geometric variables considered for the anchor include fluke length, fluke thickness, shank length, angle between fluke and shank, and shank thickness. Parametric studies are presented investigating the effect of these variables on anchor capacity and performance. A method of anchor trajectory prediction during drag embedment is developed by considering anchor behavior in conjunction with the mechanics of the anchor line. The anchor trajectory simulations indicate that an equilibrium condition rapidly develops during embedment in which the rate of anchor rotation is identical to the rate of change in the anchor line uplift angle at the shackle point. At the equilibrium state, the anchor load capacity normalized by soil strength remains constant and the anchor is in a state of incipient rotation. The anchor line angle at the seabed also influences anchor trajectory. This angle varies throughout embedment according to the mechanics of the anchor line in both the seabed and the water column.
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Acknowledgments
The writers acknowledge the support of Delmar Systems, Inc., the Department of the Interior Minerals Management Service (Cooperative Agreement No. UNSPECIFIED1435-01-99-CA-31003), and the Offshore Technology Research Center. We extend particular thanks to Evan Zimmerman of Delmar Systems, Inc. for his encouragement and support for anchor research.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 136 • Issue 1 • January 2010
Pages: 57 - 68
Copyright
© 2010 ASCE.
History
Received: Nov 6, 2008
Accepted: Jul 13, 2009
Published online: Jul 15, 2009
Published in print: Jan 2010
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