Offshore Technology Research Center


OTRC Project Summary

Project Title:

Performance of Suction Caisson Anchors in Normally Consolidated Clay

Prinicipal Investigators:

Roy Olson and Robert Gilbert


Minerals Management Service and Industry Consortium

Completion Date:

August, 2005

Final Report ID#

B162(Click to view final report abstract)

Note: This study is part of a broader project "Suction Caissons & Vertically Loaded Anchors: Model Tests (MMS Project 362).

The successful use of suction caissons in many different offshore structures led to an increasing demand on their use. Sparrevik (2001) estimated that about 300 suction caissons are operating in permanent mooring systems around the world. However, as a relatively new application, design codes lack clear guidelines for designing suction caissons. This study is part of a comprehensive research project initiated through the Offshore Technology Research Center to enhance current understanding of suction caisson anchors. The project is subdivided into: development of a detailed finite element procedure for modeling suction caissons (Vasquez, 2000, and Maniar, 2004); developing simplified plastic limit tools for prediction of suction caisson capacity (Aubeny et al. 2003); assessing the reliability of mooring systems, including the anchors, for floating production systems (Ding et al. 2005); and assessing the performance of suction caissons by conducting laboratory tests on prototype caissons. This research is part of the laboratory tests on prototype suction caissons in normally consolidated clay following the work of Pederson (2001), Mecham (2001), and Luke (2002), and in conjunction with the work by Coffman (2003) and Vanka (2004).

The presented work aims at identifying the behavior and capacity of suction caissons used for anchoring offshore floating structures in soft normally consolidated clay. Offshore structures anchored in normally consolidated clay are typical in the Gulf of Mexico and in other parts of the world. The objectives are achieved by conducting 1-g experimental tests on relatively long prototype suction caissons in large tanks of normally consolidated clay. The caisson was tested under axial, horizontal, and inclined loading. Experimental results are used in verifying and updating current design procedures and providing better understanding of the response of suction caissons to a variety of loading conditions.

Related Publications: Coffman, R. A., R. M. El-Sherbiny, A. F. Rauch, and R. E. Olson (2004), “Measured Horizontal Capacity of Suction Caissons”, Proc., Offshore Tech. Conf., Houston, Paper 16161

El-Sherbiny, R. M, Olson, R. E., Gilbert, R. B, and Vanka, S. K. (2005), “Capacity of suction caissons under inclined loading in normally consolidated clay”, Proceeding of the International Symposium on Frontiers in Offshore Geotechnics, Perth, Australia, September


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