Observations of the Effects of a Clay Layer on Suction Bucket Installation in Sand

Raffaele Ragni, Britta Bienen, Conleth D. O'Loughlin, Samuel A. Stanier, Mark J. Cassidy, Neil Morgan

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)
99 Downloads (Pure)

Abstract

Suction buckets are becoming established as a viable foundation solution for offshore wind turbines. In sand, suction-induced seepage flow reduces effective stresses at the skirt tips, which decreases penetration resistance. However, layered seabeds are often encountered in areas of offshore wind farm development. The effect of the presence of a clay layer on the suction-induced seepage flow in the sand layer is not well understood. Therefore in this study, the effects of a clay layer on suction bucket installation in dense sand was investigated. This was achieved by analyzing images of a half-bucket installed against a Perspex window. The images were captured during tests performed in a geotechnical centrifuge, such that the stress levels are realistic and relevant to field conditions. Installations in sand-over-clay were unproblematic and characterized by deformation of the sand-clay interface, with no clear interruption of the seepage flow. Installations in clay-over-sand were also successful. Uplift of the clay plug was identified as the mechanism to transfer suction to the underlying sand, creating seepage flow and thus facilitating further skirt penetration rather than terminating the installation.

Original languageEnglish
Article number04020020
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume146
Issue number5
DOIs
Publication statusPublished - 1 May 2020

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