Experimental Investigation of the Reinstallation of Spudcan Footings Close to Existing Footprints
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 135, Issue 4
Abstract
The large footprints that remain on the seabed after offshore mobile jack-up platforms have completed operations provide hazardous conditions for any future jack-up installation at that site. The slope of the footprint and varying soil strengths below the surface cause detrimental horizontal and moment loads to be induced on the spudcan during the preloading process where only vertical loads are expected. Experimental data from 12 tests investigating the reinstallation of a spudcan footing close to an existing footprint is presented in this paper. The experiments were carried out using a geotechnical drum centrifuge at a radial acceleration level equivalent to 250 times that of Earth’s gravity. The stiffness of the loading leg and model spudcan shape were scaled to ensure conditions of stress similitude between the model and prototype. In all of the experiments, an initial footprint was created. The spudcan was then offset and reinstalled with the combined vertical, horizontal, and moment loads on the spudcan recorded. The effects of reinstallation location, preloading levels, and change in leg stiffness were investigated. The worst location for reinstallation was found to be at an offset half a spudcan diameter from the initial spudcan installation. The horizontal and moment loads were also greater when a more extensive footprint was created by the initial spudcan being embedded deeper and with a higher preload. For the range of conditions tested, changing the leg stiffness did not affect the results.
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Acknowledgments
The writers wish to thank the anonymous reviewers and journal editor for their informative suggestions that have enhanced the paper’s content.
References
Bienen, B. (2007). “Development of models applicable to the three-dimensional analysis of jack-up platforms.” Ph.D. thesis, Univ. of Western Australia, Perth, Australia.
Butterfield, R., Houlsby, G. T., and Gottardi, G. (1997). “Standardised sign conventions and notation for generally loaded foundations.” Geotechnique, 47(4) 1051–1052.
Carrington, T., Hodges, W., Aldridge, T., Osborne, J., and Mirrey, J. (2003). “Jackup advanced foundation analysis by automatic re-meshing (large strain) FEA methods.” Proc. 9th Int. Conf. The Jackup Platform, C. D’Mello and L. Boswell, eds., City University, London.
Cassidy, M. J. (2003). “Centrifuge experiments investigating the reinstallation of spudcans close to existing footprints.” Geo:03296, COFS, Univ. of Western Australia, Perth, Australia.
Clunie-Ross, B. (1999). “Reinstallation of spudcan footings in clay.” Honours’ thesis, Univ. of Western Australia, Perth, Australia.
Dean, E. T. R., and Serra, H. (2004). “Concepts for mitigation of spudcan-footprint interaction in normally consolidated clay.” Proc. 14th ISOPE Conf., Toulon, France, International Society of Offshore and Polar Engineers, Cupertino, Calif.
Finnie, I. M. S. (1993). “Performance of shallow foundations in calcareous soils.” Ph.D. thesis, Univ. of Western Australia, Perth, Australia.
Foo, K. S., Quah, M. C. K., Wildberger, P., and Vazquez, J. H. (2003a). “Rack phase difference (RPD).” Proc., 9th Int. Conf. Jack-Up Platform Design, Construction and Operation, City Univ., London.
Foo, K. S., Quah, M. C. K., Wildberger, P., and Vazquez, J. H. (2003b). “Spudcan footing interaction and rack phase difference.” Proc. 9th Int. Conf. Jack-Up Platform Design, Construction and Operation, City Univ., London.
Gaudin, C., Lehane, B. M., and Wallis, P. F. (2005). “A centrifuge study of the monotonic and cyclic resistance of piles and pile groups in sand.” Proc. Frontiers in Offshore Geotechnics: ISFOG 2005, Taylor and Francis, London, 749–755.
Hunt, R. J., and Marsh, P. D. (2004). “Opportunities to improve the operational and technical management of jack-up deployments.” Mar. Struct., 17(3–4), 261–273.
Jardine, R. J., Kovecevic, N., Hoyle, M. J. R., Sidhu, H. K., and Letty, A. (2001). “A study of eccentric jack-up penetration into infilled footprint craters.” Proc. 8th Int. Conf. The Jackup Platform, C. D’Mello and L. Boswell, eds., City Univ., London.
Leung, C. F., Gan, C. T., and Chow, Y. K. (2007). “Shear strength changes within jack-up spudcan footprint.” Proc. 17th Int. Offshore and Polar Engineering Conf., Lisbon, Portugal, International Society of Offshore and Polar Engineers, Cupertino, Calif., 1504–1509.
Martin, C. M. (1994). “Physical and numerical modelling of offshore foundations under combined loads.” D.Phil. thesis, Univ. of Oxford, Oxford, U.K.
Osborne, J. J., Pelley, D., Nelson, C., and Hunt, R. (2006). “Unpredicted jack-up foundation performance.” Proc., Jack-Up Asia Conf. and Exhibition, PetroMin, Singapore.
Reardon, M. J. (1986). “Review of the geotechnical aspects of jack-up unit operations.” Ground Eng., 19(7), 21–26.
Stewart, D. P. (1992). “Lateral loading of piled bridge abutments due to embankment construction.” Ph.D. thesis, Univ. of Western Australia, Perth, Australia.
Stewart, D. P., Boyle, R. S., and Randolph, M. F. (1998). “Experience with a new drum centrifuge.” Proc., Int. Conf. Centrifuge ’98, Tokyo, Vol. 1, Balkema, Rotterdam, The Netherlands, 35–40.
Stewart, D. P., and Finnie, I. M. S. (2001). “Spudcan-footprint interaction during jack-up workovers.” Proc. 11th Int. Offshore and Polar Engineering Conf. (ISOPE), Stavanger, Norway, International Dociety of OFfshore and Polar Engineers, Cupertino, Calif.
Stewart, D. P., and Randolph, M. F. (1991). “A new site investigation tool for the centrifuge.” Proc. Int. Conf. on Centrifuge Modelling—Centrifuge, 91, Boulder, Colo., Balkema, Rotterdam, 531–538.
Stewart, D. P., and Randolph, M. F. (1994). “T-bar penetration testing in soft clay.” J. Geotech. Engrg., 120(12), 2230–2235.
Stonor, R. W. P., Hoyle, M. J. R., Nelson, K., Smith, N. P., and Hunt, R. J. (2004). “Recovery of an elevated jack-up with leg bracing member damage.” Mar. Struct., 17(3–4), 325–251.
Teh, K. L., Byrne, B. W., and Houlsby, G. T. (2006) “Effects of seabed irregularities on loads developed in legs of jack-up units.” Proc. Jack-Up Asia Conf. and Exhibition, PetroMin, Singapore.
Treacy, G. (2003). “Reinstallation of spudcan footings next to existing footprints.” Honours’ thesis, Univ. of Western Australia, Perth, Australia.
Watson, P. G. (1999). “Performance of skirted foundations for offshore structures.” Ph.D. thesis, Univ. of Western Australia, Perth, Australia.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 135 • Issue 4 • April 2009
Pages: 474 - 486
Copyright
© 2009 ASCE.
History
Received: Apr 4, 2006
Accepted: Oct 6, 2008
Published online: Apr 1, 2009
Published in print: Apr 2009
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