Geotechnical design of suction caisson in clay

Suction caissons have proven to be economical and easy to install for anchoring deepwater offshore structures with taut or semi-taut moorings, such as FPSOs (Floating Production Storage Offloading), SPARs, FPSs (Floating Production Systems), etc. However, due to the complex loading conditions and paucity of model test database, the design of suction caissons is still in the state-of-the-art phase, and no industry consensus has been reached. Unlike traditional driven piles, suction caissons are different in many ways, such as the installation methods and load-resisting mechanisms. This paper systematically discusses the geotechnical design of suction caissons installed in clay stratigraphies. Many important aspects and factors involved in suction caisson design, such as set-up effects, soil failure modes, padeye location optimization, axial capacities estimation, cyclic loading and sustained load effects, etc. are brought up for discussion. Limit equilibrium methods are used as an effective way to estimate suction caisson capacity and caisson penetration/removal parameters as well. Beam-column and Finite Element Analyses are more advanced methods to better understand caisson load-displacement behavior and verify load capacity derived from the limit equilibrium methods. Finally, suggestions for future research are given on how to clarify the uncertainties associated with current suction caisson designs.