Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Geotechnical and Structural Design Considerations for Finned Piles Numerical and Analytical Results
Pablo Castillo Garcia (1), Gérald Gerometta (2)Geotechnical (1) and Structural (2) Department, Subsea 7
Suresnes, France

Stylianos Panayides
Geotechnical Department, Subsea 7Sutton, United Kingdom

increase in lateral capacity from 10% to 60% as compared to a monopile
where the optimal fin location was not at mudline. In addition, Durhkopand Grabe (2008) showed that any pile with fins has a stiffer system
response as compared to a monopile, regardless of the shape and positionof the wings. Subsequently, Peng et al., (2010) presented that for amonopile to provide the same resistance as a fin-enhanced pile, then thediameter of the monopile must exceed the core diameter of the finenhanced pile. Further salient findings can be found in Irvine et al.,(2003), Grabe and Duhrkop (2007), Bienen et al., (2012) Duhrkop andGrabe (2009), Rudolph and Grabe (2013).

ABSTRACTThis paper offers robust analytical equations and design configuration
for finned piles based on the results of an extensive three-dimensional
finite element analysis considering geotechnical and structural
calculations. The expressions presented in this paper consider theinfluence that different aspect ratio of the caisson, fin configuration andsoil characteristics, have on the finned pile response then enabling fasterand optimised design process for developments in very soft deep-water
clays.

Castillo-Garcia and Panayides (2021) evaluates the impact of varying fin
length, shape, orientation and location on the combined capacity ofsuction piles by means of three-dimensional finite element analysis
targeting deep-water deposits of soft clay. Typical applications of finned
piles require varying design considerations owing to the different design
drivers. For top loaded, the optimal improvement in load carrying
capacity is realised when fins are located towards the upper part of theskirt while for side loaded piles, the optimisation is achieved when thefins are located close to the attachment point with a potential steel
requirement reduction of 25% can be achieved.

KEY WORDS: Foundations; anchors; suction piles; fins; numericalmodelling; analytical equations; deepwater; soft clay.
INTRODUCTION
Suction piles for deep-water developments present a staple foundation
solution. Owing to their excellent holding capacity characteristics in thecombined V-H space, suction piles are deployed for a variety ofapplications, including holdback or hold down anchors for in-line
pipeline structures and risers, mitigations against pipeline walking, orindeed for pipeline initiation purposes. The load for the applications
mentioned above is usually transferred to the piles through the top plate(top loaded). There are occasions where to maximise the efficiency ofthe suction piles, the load is transferred via a padeye located at the sideof the skirt as typically adopted for mooring piles of Floating Production,
Storage and Offloading (FPSO) vessels. Depending on the application,
suction piles may experience large magnitude horizontal loads, either
arising from environmental conditions, operational loading fromhydrocarbon circulation or infrastructure installation.

Scope of StudyThe Geotechnical and Structural Department of Subsea 7 continued thework presented in Castillo-Garcia and Panayides (2021), hence bothstudies should be read in conjunction. The finned pile concept isanalysed from structural point of view and analytical terms have been
extracted from the numerical research enabling faster and optimised
design process for developments in very soft deep-water clays andmonotonic loading conditions. Supplementary analysis considering
finned piles in sandy soil profiles and cyclic loading with soil strength
degradation are outside the remit of this paper. Indication on how toestimate the horizontal capacity and V-H envelopes through analyticalequations, updating and comparing past references is the objective of thisresearch. Some information is not disclosed for commercial purposes.

Universities of Newcastle (UK) and Hamburg (Germany) started toinvestigate in the early 2000s how the addition of fins to the skirt canenhance the lateral response of suction piles, having the focus on
windfarm foundations. Grabe and Duhrkop (2007) found a potential

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