Partially mobile shallow subsea foundations: a practical analysis framework
Partially mobile shallow subsea foundations: a practical analysis framework
The geotechnical design of partially mobile subsea foundations (mudmats) for pipeline/flowline end terminals (PLETs) is presented in this paper. A partially mobile mudmat represents a fit-for-purpose engineering solution that has significant commercial competitiveness. The partially mobile design lies between that of a fully anchored mudmat (which is designed for negligible movements but may be too large, causing installation issues or requiring corner piles to anchor) and a fully mobile mudmat (which moves to fully accommodate the expansion of the connected pipeline, but may suffer excessive settlements that compromise the structural integrity). The partially mobile mudmat is suited to deepwater soft soil conditions. The aim of this work is to help mature this new concept and technology for practical design and to inspire future research to improve the accuracy of predictions. The objective of the paper is to present simple new analytical solutions to predict the long-term accumulated displacements and rotations of a partially mobile mudmat on soft clayey deposits subjected to cyclic loading. The proposed displacement prediction framework combines established elements of consolidation theory, plasticity theory, and critical-state soil mechanics (CSSM). Typical ranges of soil properties pertinent to a partially mobile mudmat are provided for deepwater Gulf of Mexico (GoM) soft clays, and a design analysis example is provided. For these conditions, it is concluded that the dominant displacements of a partially mobile mudmat are caused by primary consolidation and plastic failure. Recommendations for further improvement are provided to inspire further research.
Clay, Consolidation, Critical state, Cyclic, Mudmat, Partially mobile
Chen, Jinbo
1457878b-5f48-4687-93c9-158f391b0e09
White, David
a986033d-d26d-4419-a3f3-20dc54efce93
1 August 2021
Chen, Jinbo
1457878b-5f48-4687-93c9-158f391b0e09
White, David
a986033d-d26d-4419-a3f3-20dc54efce93
Chen, Jinbo and White, David
(2021)
Partially mobile shallow subsea foundations: a practical analysis framework.
Journal of Geotechnical and Geoenvironmental Engineering, 147 (8), [04021064].
(doi:10.1061/(ASCE)GT.1943-5606.0002573).
Abstract
The geotechnical design of partially mobile subsea foundations (mudmats) for pipeline/flowline end terminals (PLETs) is presented in this paper. A partially mobile mudmat represents a fit-for-purpose engineering solution that has significant commercial competitiveness. The partially mobile design lies between that of a fully anchored mudmat (which is designed for negligible movements but may be too large, causing installation issues or requiring corner piles to anchor) and a fully mobile mudmat (which moves to fully accommodate the expansion of the connected pipeline, but may suffer excessive settlements that compromise the structural integrity). The partially mobile mudmat is suited to deepwater soft soil conditions. The aim of this work is to help mature this new concept and technology for practical design and to inspire future research to improve the accuracy of predictions. The objective of the paper is to present simple new analytical solutions to predict the long-term accumulated displacements and rotations of a partially mobile mudmat on soft clayey deposits subjected to cyclic loading. The proposed displacement prediction framework combines established elements of consolidation theory, plasticity theory, and critical-state soil mechanics (CSSM). Typical ranges of soil properties pertinent to a partially mobile mudmat are provided for deepwater Gulf of Mexico (GoM) soft clays, and a design analysis example is provided. For these conditions, it is concluded that the dominant displacements of a partially mobile mudmat are caused by primary consolidation and plastic failure. Recommendations for further improvement are provided to inspire further research.
Text
Chen and White-R1 Final Submitted-02-25-2021
- Accepted Manuscript
More information
Accepted/In Press date: 2 April 2021
e-pub ahead of print date: 28 May 2021
Published date: 1 August 2021
Additional Information:
Funding Information:
The authors thank the management of Shell Global Solutions (US) Inc. and Shell International Exploration and Production Inc. for permission to publish this paper. D. White acknowledges the support of the Shell Chair in Offshore Engineering, funded by Shell Australia, which supported early work on this paper while he was based at the University of Western Australia. The views and opinions are those of the authors alone and do not necessarily reflect those of any of the sponsors or other contributors.
Publisher Copyright:
© 2021 American Society of Civil Engineers.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
Keywords:
Clay, Consolidation, Critical state, Cyclic, Mudmat, Partially mobile
Identifiers
Local EPrints ID: 450631
URI: http://eprints.soton.ac.uk/id/eprint/450631
ISSN: 1090-0241
PURE UUID: c3a9062f-cfe6-4cb2-b971-50f78b28e642
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Date deposited: 05 Aug 2021 16:31
Last modified: 18 Mar 2024 03:42
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Author:
Jinbo Chen
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