Three-Dimensional Lower and Upper Bound Analyses of Pile Systems
Publication: International Journal of Geomechanics
Volume 20, Issue 12
Abstract
The objective of this paper is to present simplified methods for determining the three-dimensional (3D) system capacities of pile foundations based on the lower and upper bound theorems of plasticity. The failure surface for a typical long offshore pile subjected to 3D head loads is derived based on the lower bound (LB) theorem of plasticity, and the LB capacity of a pile system is then proposed. Using the failure mechanism determined from the elastic solution in the LB analysis of a pile system, the upper bound (UB) capacity of the pile system is obtained from the energy-balancing equation. An actual offshore platform is selected as a case study to demonstrate the proposed methods. The current methods extend the planar limit analysis by incorporating global torsion and out-of-plane failures and can be useful in designing and assessing pile systems.
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Acknowledgments
The majority of this work was completed when the first author was at The University of Texas at Austin. We acknowledge the American Petroleum Institute (API) for providing the financial support to conduct this work. We also acknowledge the continuous support from the Bureau of Safety and Environmental Enforcement, the fruitful discussions with Dr. Albert Ku and Dr. J. Y. Chen (formerly with Energo Engineering), and Mr. Vul Thang from Bentley Systems, Inc. We also acknowledge Shell Global Solutions (US) Inc. and Shell International Exploration and Production Inc. for the permission to publish this paper. The views and opinions contained in this paper are those of the authors alone and do not necessarily reflect those of the sponsors or other contributors.
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Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 20 • Issue 12 • December 2020
Copyright
© 2020 American Society of Civil Engineers.
History
Received: Nov 21, 2019
Accepted: Jul 31, 2020
Published online: Sep 22, 2020
Published in print: Dec 1, 2020
Discussion open until: Feb 22, 2021
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