Observations of the Effects of a Clay Layer on Suction Bucket Installation in Sand
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 146, Issue 5
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.
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Data Availability Statement
The data obtained from the centrifuge tests are available from the corresponding author by request. GeoPIV-RG is a free image analysis module for MATLAB designed for geotechnical and structural engineering research applications, available from http://www.geopivrg.com/.
Acknowledgments
This work forms part of the activities of the Centre for Offshore Foundation Systems (COFS), which is currently supported as a Centre of Excellence by the Lloyd’s Register Foundation. Lloyd’s Register Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research. This research is also supported through the Australian Research Council Linkage Project 180100024. The authors are grateful for this support. The views presented in this paper represent those of the authors and not necessarily those of their respective employers.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 146 • Issue 5 • May 2020
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©2020 American Society of Civil Engineers.
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Received: Apr 23, 2019
Accepted: Oct 23, 2019
Published online: Mar 9, 2020
Published in print: May 1, 2020
Discussion open until: Aug 9, 2020
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