Effect of Installation Method on External Shaft Friction of Caissons in Soft Clay
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 135, Issue 5
Abstract
The influence of the installation method on the soil flow pattern, resulting external radial total stress changes, and final external shaft friction after consolidation has been investigated for caissons in soft clay by means of centrifuge model tests, large deformation finite-element (FE) analysis, and a simple cavity expansion approach. Both the centrifuge measurements and the FE results show that more soil is forced into the caisson under suction than under jacking. However, the difference in the resulting external radial total stress changes or penetration-induced excess pore-water pressure is much less significant, since the expansion-induced excess pore pressure is smaller for thin-walled caissons than for driven piles. After subsequent consolidation, the influence of the installation method reduces further, and the final shaft friction ratios are close for the two installation methods. Based on the magnitude of heave ratios derived from the centrifuge measurements and the FE analysis, a simple form of cavity expansion approach can reasonably estimate external radial stress changes during installation and after consolidation, and final shaft friction ratios for the caissons. An approach for estimating the external shaft friction ratios for vertical pullout of sealed caissons is proposed.
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Acknowledgments
The work presented in this paper forms part of the activities of the Centre for Offshore Foundation Systems (COFS), established under the Australian Research Council’s Research Centres Program. The first and second writers held International Postgraduate Research Scholarships and University Postgraduate Awards from the University of Western Australia. The support is gratefully appreciated.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 135 • Issue 5 • May 2009
Pages: 605 - 615
Copyright
© 2009 ASCE.
History
Received: Jun 1, 2007
Accepted: Aug 25, 2008
Published online: Feb 11, 2009
Published in print: May 2009
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