100 likes | 220 Views
Suction Anchorage. Past and Future. By: Sean-Philip H Bolduc CVE 582 Fall 2008 Seabed Geotechnics Dept of Civil and Environmental Engineering. Introduction. Suction Caissons: An alternative to traditional foundations. Introduction… continued.
E N D
Suction Anchorage. Past and Future. By: Sean-Philip H Bolduc CVE 582 Fall 2008 Seabed Geotechnics Dept of Civil and Environmental Engineering
Introduction Suction Caissons: An alternative to traditional foundations.
Introduction… continued Examples of Traditional Foundations • Driven Pile • Drag Anchors • Gravity Caissons
Introduction… continued Suction Caissons Advantages: • Cost cutting measures • Construction (saved material) • Transportation • Installation • Removal • Ease of Installation and removal • Reduced Sediment Potential • Increased Short Term Loading Capacity due to Suction induced Pore Pressures
History of Offshore Foundations Major Drive to go offshore - Oil Discovery • 1947 First Offshore Platform built off the Gulf of Mexico • Currently more the 6,800 offshore structures (Alghamdi 2005) • Types of Common Platforms • Steel Pile Jacket Platforms (SPJ) • Gravity Based Structures (GBS) • Tension Leg Platform • Spar Platform • Windmill Tripod Design (RAMBOLL)
History… Continued Suction Foundations • Mooring anchors off the coast of Denmark by Senperee and Auvergne • 1989 Gullfak C. GBS first to use suction caisson foundation in clay • Snorre. First TLP founded in clay • Draupner E. First founded in Clay
Installation Two Stages • Lowered to sea floor and imbedded under self weight • Suction force created by pumping water out of top • Clays: Suction force exceeds tip and skin resistance • Sand: Hydraulic gradient reduced soil resistance to zero
In-Service Suction Caissons • Active Suction (pumps left on) • Temporary Anchorage • Tops are Sealed • Suction Pressures increase resistance to Pullout Force • Tops are left open • Act as standard Pile – rely on just tip and skin resistance
Conclusion Suction Foundation Technology has great potential • Ease of construction Installation and Possible Removal • Durable under short term loading • Wave and Wind Loading • Showing it to be more economical option to Traditional Foundation Options
References Colliat, J.L., Boisard, P., Sparrevik, P., Gramet, J.C., (1998). Design and Installation of Suction Anchor Piles at Soft Clay Site, Journal of Waterway, Port, Coastal, and Ocean Engineering , July/August, pp179-188. Rasmusse, J.L., Feid, T., Sorensen, P.H, (2000). Bucket Foundation for Offshore Wind Farms Comparison of Simplified Model and FE-Calculations, Ramboll, http://www.ramboll-wind.com/PDF/OWEMES2000.pdf Sukumaran, B.. Suction Caisson Anchors – A Better Option for Deep Water Applications, Rowan University Tran, M.N., Randolph, M.F., Airey, D.W., (2007). Installation of Suction Caissons in Sand with Silt Layers, Journal of Geotechnical and Geoenvironmental Engineering, Oct 2007, pp.1183-1191 Westgate, Z.J., DeJong, J.T. Geotechnical considerations for offshore wind turbines. Technical report, Massachusetts Technology Collaborative Renewable Energy Tryst, 2005. Zhang, J.H., Zhang, L.M., Lu, X.B., (2007). Centrifuge modeling of suction bucket foundations for platforms under ice-sheet-induced cyclic lateral loadings, Ocean Engineering, Vol 34, pp1069-1079. Zhou, H, Randolph, M.F., (2006). Large deformation analysis of suction caisson installation in clay, Can. Geotech, Vol 43, 2006, pp1344-1357.