Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures

Andrew Brennan; Michael Brown; Jonathan Knappett; Catrina McMillan; H. Aldaikh; Andrew A. Small; Damian R. Morrow

doi:10.3723/OSIG17.749

Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures

Andrew Brennan, Michael Brown, Jonathan Knappett, Catrina McMillan, H. Aldaikh, Andrew A. Small, Damian R. Morrow

Civil Engineering

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

124 Downloads (Pure)

Abstract

Decommissioning of subsea structures founded on shallow foundations currently requires the complete re-moval of the structure, but there are challenges in predicting the associated recovery loads. This work exam-ines the extraction behaviour of shallow, skirted, square foundations in soft clay by means of a series of dis-placement-controlled small scale model tests. Skirt length, uplift rate, surface drainage condition and pre-load were all varied. Extraction behaviour is seen to be different depending on whether the foundation re-tains a soil plug which in turn seems to depend on the kinematics rather than rate effects. Prediction of re-covery loads based on assuming plugged behaviour in all cases provided an upper bound without excessive conservatism. Prediction of recovery loads based on model preload was only successful under certain condi-tions, and thus should be considered as an estimate only.

Original language	English
Title of host publication	Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments
Subtitle of host publication	Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London
Publisher	Society for Underwater Technology
Pages	749-756
Number of pages	8
Volume	1-2
ISBN (Print)	9780906940570 (hbk) Volume 1, 9780906940587 (hbk) Volume 2
DOIs	https://doi.org/10.3723/OSIG17.749
Publication status	Published - 12 Sept 2017
Event	8th Offshore Site Investigation and Geotechnics International Conference: ‘Smarter Solutions for Future Offshore Developments’ - Royal Geographical Society, London, United Kingdom Duration: 12 Sept 2017 → 14 Sept 2017 http://www.sutconnects.com/ (Link to conference website)

Conference

Conference	8th Offshore Site Investigation and Geotechnics International Conference
Country/Territory	United Kingdom
City	London
Period	12/09/17 → 14/09/17
Internet address	http://www.sutconnects.com/ (Link to conference website)

Keywords

Decommissioning
Skirted foundations
UPLIFT
breakout
Clay

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.3723/OSIG17.749

Author Accepted ManuscriptAccepted author manuscript, 892 KB

1 Conference contribution

Decommissioning of offshore piles using vibration
Davidson, C., Brown, M., Brennan, A. & Knappett, J., 2017, Proceedings of the 27th International Ocean and Polar Engineering Conference, ISOPE 2017. Chung, J. S. & Wang, H. H. (eds.). United States: International Society of Offshore and Polar Engineers, Vol. 2. p. 666-673 8 p. (Proceedings of the International Ocean and Polar Engineering Conference; vol. 2).
Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Open Access
File

1 Membership of group

EPSRC Supergen Offshore Renewable Energy (ORE) project, Research Alignment Group (RAG) (External organisation)
Brown, M. (Member)
Oct 2018
Activity: Membership types › Membership of group

Cite this

Brennan, A., Brown, M., Knappett, J., McMillan, C., Aldaikh, H., Small, A. A., & Morrow, D. R. (2017). Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures. In Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments: Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London (Vol. 1-2, pp. 749-756). Society for Underwater Technology. https://doi.org/10.3723/OSIG17.749

Brennan, Andrew ; Brown, Michael ; Knappett, Jonathan et al. / Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures. Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments: Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London. Vol. 1-2 Society for Underwater Technology, 2017. pp. 749-756

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title = "Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures",

abstract = "Decommissioning of subsea structures founded on shallow foundations currently requires the complete re-moval of the structure, but there are challenges in predicting the associated recovery loads. This work exam-ines the extraction behaviour of shallow, skirted, square foundations in soft clay by means of a series of dis-placement-controlled small scale model tests. Skirt length, uplift rate, surface drainage condition and pre-load were all varied. Extraction behaviour is seen to be different depending on whether the foundation re-tains a soil plug which in turn seems to depend on the kinematics rather than rate effects. Prediction of re-covery loads based on assuming plugged behaviour in all cases provided an upper bound without excessive conservatism. Prediction of recovery loads based on model preload was only successful under certain condi-tions, and thus should be considered as an estimate only.",

keywords = "Decommissioning, Skirted foundations, UPLIFT, breakout, Clay",

author = "Andrew Brennan and Michael Brown and Jonathan Knappett and Catrina McMillan and H. Aldaikh and Small, {Andrew A.} and Morrow, {Damian R.}",

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note = "8th Offshore Site Investigation and Geotechnics International Conference : {\textquoteleft}Smarter Solutions for Future Offshore Developments{\textquoteright} ; Conference date: 12-09-2017 Through 14-09-2017",

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Brennan, A , Brown, M , Knappett, J, McMillan, C, Aldaikh, H, Small, AA & Morrow, DR 2017, Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures. in Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments: Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London. vol. 1-2, Society for Underwater Technology, pp. 749-756, 8th Offshore Site Investigation and Geotechnics International Conference, London, United Kingdom, 12/09/17. https://doi.org/10.3723/OSIG17.749

Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures. / Brennan, Andrew ; Brown, Michael ; Knappett, Jonathan et al.
Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments: Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London. Vol. 1-2 Society for Underwater Technology, 2017. p. 749-756.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures

AU - Brennan, Andrew

AU - Brown, Michael

AU - Knappett, Jonathan

AU - McMillan, Catrina

AU - Aldaikh, H.

AU - Small, Andrew A.

AU - Morrow, Damian R.

PY - 2017/9/12

Y1 - 2017/9/12

N2 - Decommissioning of subsea structures founded on shallow foundations currently requires the complete re-moval of the structure, but there are challenges in predicting the associated recovery loads. This work exam-ines the extraction behaviour of shallow, skirted, square foundations in soft clay by means of a series of dis-placement-controlled small scale model tests. Skirt length, uplift rate, surface drainage condition and pre-load were all varied. Extraction behaviour is seen to be different depending on whether the foundation re-tains a soil plug which in turn seems to depend on the kinematics rather than rate effects. Prediction of re-covery loads based on assuming plugged behaviour in all cases provided an upper bound without excessive conservatism. Prediction of recovery loads based on model preload was only successful under certain condi-tions, and thus should be considered as an estimate only.

AB - Decommissioning of subsea structures founded on shallow foundations currently requires the complete re-moval of the structure, but there are challenges in predicting the associated recovery loads. This work exam-ines the extraction behaviour of shallow, skirted, square foundations in soft clay by means of a series of dis-placement-controlled small scale model tests. Skirt length, uplift rate, surface drainage condition and pre-load were all varied. Extraction behaviour is seen to be different depending on whether the foundation re-tains a soil plug which in turn seems to depend on the kinematics rather than rate effects. Prediction of re-covery loads based on assuming plugged behaviour in all cases provided an upper bound without excessive conservatism. Prediction of recovery loads based on model preload was only successful under certain condi-tions, and thus should be considered as an estimate only.

KW - Decommissioning

KW - Skirted foundations

KW - UPLIFT

KW - breakout

KW - Clay

U2 - 10.3723/OSIG17.749

DO - 10.3723/OSIG17.749

M3 - Conference contribution

SN - 9780906940570 (hbk) Volume 1

SN - 9780906940587 (hbk) Volume 2

VL - 1-2

SP - 749

EP - 756

BT - Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments

PB - Society for Underwater Technology

T2 - 8th Offshore Site Investigation and Geotechnics International Conference

Y2 - 12 September 2017 through 14 September 2017

ER -

Brennan A , Brown M , Knappett J, McMillan C, Aldaikh H, Small AA et al. Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures. In Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments: Proceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London. Vol. 1-2. Society for Underwater Technology. 2017. p. 749-756 Epub 2017 Jan 1. doi: 10.3723/OSIG17.749

Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures

Abstract

Conference

Keywords

UN SDGs

Access to Document

Fingerprint

Research output

Decommissioning of offshore piles using vibration

Activities

EPSRC Supergen Offshore Renewable Energy (ORE) project, Research Alignment Group (RAG) (External organisation)

Cite this