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Abstract
© 2016, ICE Publishing. All rights reserved.
Jack-up installation is typically discontinuous with seawater ballast being taken on and shed again periodically to elevate the hull out of the ocean as the spudcan footings penetrate the soil. Any pauses in the footing penetration provide the opportunity for consolidation to occur in sufficiently permeable cohesive soils. The undrained shear strength underneath the spudcan is increased during consolidation, which enhances the penetration resistance within a limited extent immediately after the consolidation. This phenomenon has been explored in a limited number of centrifuge tests, but cannot be reproduced using conventional finite-element methods. An effective stress large-deformation finiteelement approach based on periodic mesh regeneration is employed to capture the entire process of ‘penetration-consolidation-penetration’, with the modified Cam-clay model being incorporated to represent the behaviour of normally consolidated kaolin clays. The numerical model established is verified by comparison with two series of centrifuge tests before exploring the influence of key parameters, including consolidation depth, consolidation duration, coefficient of consolidations, anisotropy of permeability and loads held during consolidation. The normalised consolidation duration is identified as the dominant factor that affects the post-consolidation peak in penetration resistance. A simple method is proposed to estimate the post-consolidation penetration resistance.
Jack-up installation is typically discontinuous with seawater ballast being taken on and shed again periodically to elevate the hull out of the ocean as the spudcan footings penetrate the soil. Any pauses in the footing penetration provide the opportunity for consolidation to occur in sufficiently permeable cohesive soils. The undrained shear strength underneath the spudcan is increased during consolidation, which enhances the penetration resistance within a limited extent immediately after the consolidation. This phenomenon has been explored in a limited number of centrifuge tests, but cannot be reproduced using conventional finite-element methods. An effective stress large-deformation finiteelement approach based on periodic mesh regeneration is employed to capture the entire process of ‘penetration-consolidation-penetration’, with the modified Cam-clay model being incorporated to represent the behaviour of normally consolidated kaolin clays. The numerical model established is verified by comparison with two series of centrifuge tests before exploring the influence of key parameters, including consolidation depth, consolidation duration, coefficient of consolidations, anisotropy of permeability and loads held during consolidation. The normalised consolidation duration is identified as the dominant factor that affects the post-consolidation peak in penetration resistance. A simple method is proposed to estimate the post-consolidation penetration resistance.
Original language | English |
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Pages (from-to) | 947-952 |
Number of pages | 6 |
Journal | Geotechnique |
Volume | 66 |
Issue number | 11 |
Early online date | 1 Jul 2016 |
DOIs | |
Publication status | Published - 1 Nov 2016 |
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Dive into the research topics of 'Numerical investigation of penetration of a large-diameter footing into normally consolidated kaolin clay with a consolidation phase'. Together they form a unique fingerprint.Projects
- 2 Finished
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New Frontiers in Offshore Geotechnics: Securing Australia's Energy Future
Cassidy, M. (Investigator 01)
ARC Australian Research Council
1/01/14 → 28/02/19
Project: Research
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Predicting the Foundation Performance of Offshore Jack Up Drilling Rigs in Intermediate Soils
Bienen, B. (Investigator 01) & Cassidy, M. (Investigator 02)
ARC Australian Research Council
1/01/11 → 31/12/16
Project: Research