Model Testing of Recovery Loads for Decommissioning Skirted Subsea Structures

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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 languageEnglish
Title of host publicationOffshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments
Subtitle of host publicationProceedings of the 8th International Conference, held 12–14 September 2017 at the Royal Geographical Society, London
PublisherSociety for Underwater Technology
Pages749-756
Volume1-2
ISBN (Print)9780906940570 (hbk) Volume 1, 9780906940587 (hbk) Volume 2
Publication statusPublished - 12 Sep 2017
Event8th Offshore Site Investigation and Geotechnics International Conference: ‘Smarter Solutions for Future Offshore Developments’ - Royal Geographical Society, London, United Kingdom
Duration: 12 Sep 201714 Sep 2017
http://www.sutconnects.com/ (Link to conference website)

Conference

Conference8th Offshore Site Investigation and Geotechnics International Conference
CountryUnited Kingdom
CityLondon
Period12/09/1714/09/17
Internet address

Keywords

  • Decommissioning
  • Skirted foundations
  • UPLIFT
  • breakout
  • Clay

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