Critical Skirt Spacing for Shallow Foundations under General Loading
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 139, Issue 9
Abstract
Finite-element limit analysis is used to identify the critical internal skirt spacing for the undrained failure of shallow skirted foundations under conditions of plane strain based on the criterion that the confined soil plug should ideally displace as a rigid block, such that optimal bearing capacity is realized. General loading (vertical, horizontal, and moment) is considered for foundations with skirt embedments ranging from 5 to 50% of the foundation breadth in soil having either uniform strength or strength proportional to depth. The results explicitly identify the number of internal skirts required to ensure soil plug rigidity under arbitrary combinations of horizontal and moment loading expressed as a function of the normalized skirt embedment and the maximum expected level of vertical loading as a fraction of the ultimate vertical bearing capacity. It is shown that fewer internal skirts are required with increasing normalized foundation embedment, but more internal skirts are required with increasing soil strength heterogeneity. The results also indicate the potential for a significant reduction in capacity if insufficient skirts are provided, such that plastic deformation is permitted to occur within the soil plug.
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Acknowledgments
The work described in this paper forms part of the activities of the Special Research Centre for Offshore Foundation Systems (COFS), currently supported as a node of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering. The work presented in this paper was supported through ARC grant DP0988904. This support is gratefully acknowledged. The work was carried out during an academic visit of the first and second authors to the Department of Engineering Science, University of Oxford, United Kingdom. The support of the Department of Engineering Science and the University of Oxford is gratefully acknowledged. MATLAB scripting advice from Professor David White is also gratefully acknowledged.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 139 • Issue 9 • September 2013
Pages: 1554 - 1566
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Jun 19, 2012
Accepted: Dec 18, 2012
Published online: Dec 21, 2012
Published in print: Sep 1, 2013
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