This paper presents a numerical based study on the undrained load capacity of a typical torpedo anchor embedded in a purely cohesive isotropic soil using a three-dimensional nonlinear finite element model. In this model, the soil is simulated with solid elements capable of representing its nonlinear physical behavior and the large deformations involved. The torpedo anchor is also modeled with solid elements, and its geometry is represented in detail. Moreover, the anchor-soil interaction is addressed with contact finite elements that allow relative sliding with friction between the surfaces in contact. A number of analyses are conducted in order to understand the response of this type of anchor when different soil undrained shear strengths, load directions, and number and width of flukes are considered. The results obtained indicate two different failure mechanisms: The first one involves significant plastic deformation before collapse and, consequently, mobilizes a great amount of soil; the second is associated with the development of a limited shear zone near the edge of the anchor and mobilizes a small amount of soil. The total contact area of the anchor seems to be an important parameter in the determination of its load capacity, and, consequently, the increase in the undrained shear strength and the number of flukes and/or their width significantly increases the load capacity of the anchor.

1.
Ehlers
,
C. J.
,
Young
,
A. G.
, and
Chen
,
J. H.
, 2004, “
Technology Assessment of Deepwater Anchors
,”
Proceedings of the 36th Offshore Technology Conference
, Houston, TX, Paper No. 15265.
2.
Wodehouse
,
J.
,
George
,
B.
, and
Luo
,
Y.
, 2007, “
The Development of a FPSO for the Deepwater Gulf of Mexico
,”
Proceedings of the 39th Offshore Technology Conference
, Houston, TX, Paper No. 18560.
3.
Medeiros
,
C. J.
, Jr.
, 2002, “
Low Cost Anchor System for Flexible Risers in Deep Waters
,”
Proceedings of the Offshore Technology Conference
, Houston, TX, Paper No. 14151.
4.
Araújo
,
J. B.
,
Machado
,
R. D.
, and
Medeiros
,
C. P.
, Jr.
, 2004, “
High Holding Power Torpedo Pile—Results for the First Long Term Application
,”
Proceedings of the ASME 23rd OMAE Conference
, Vancouver, Paper No. 51201.
5.
O’Loughlin
,
C. D.
,
Randolph
,
M. F.
, and
Richardson
,
M. D.
, 2004, “
Experimental and Theoretical Studies of Deep Penetrating Anchors
,”
Proceedings of the 36th Offshore Technology Conference
, Houston, TX, Paper No. 16841.
6.
O’Loughlin
,
C. D.
,
Richardson
,
M. D.
, and
Randolph
,
M. F.
, 2009, “
Centrifuge Tests on Dynamically Installed Anchors
,”
Proceedings of the ASME 28th International Conference on Ocean, Offshore and Arctic Engineering
, Honolulu, HI, Paper No. 80238.
7.
Richardson
,
M. D.
,
O’Loughlin
,
C. D.
,
Randolph
,
M. F.
, and
Gaudin
,
C.
, 2009, “
Setup Following Installation of Dynamic Anchors in Normally Consolidated Clay
,”
J. Geotech. Geoenviron. Eng.
1090-0241,
135
(
4
), pp.
487
496
.
8.
API
, 2005, “
Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms—Working Stress Design (RP 2A-WSD)
,”
20th ed.
, American Petroleum Institute, USA.
9.
ANSYS
, 2009, ANSYS Help (Version 12), Mechanical APDL, Ansys Inc.
10.
Sagrilo
,
L. V. S.
,
de Sousa
,
J. R. M.
,
Lima
,
E. C. P.
,
Porto
,
E. C.
, and
Fernandes
,
J. V. V.
, 2010, “
Reliability-Based Design of Torpedo Anchors
,”
Proceedings of the ASME 29th International Conference on Ocean, Offshore and Arctic Engineering
, Shanghai, Paper No. 21082.
11.
Potts
,
D. M.
, and
Zdravkovic
,
L.
, 1999,
Finite Element Analysis in Geotechnical Engineering—Theory
,
1st ed.
,
Thomas Telford
,
London, UK
.
12.
Chen
,
W. F.
, and
Baladi
,
G. Y.
, 1985,
Soil Plasticity: Theory and Implementation
,
1st ed.
,
Elsevier Science
,
The Netherlands
.
13.
Wriggers
,
P.
, and
Korelc
,
P.
, 1996, “
On Enhanced Strain Methods for Small and Finite Deformations of Solids
,”
Comput. Mech.
0178-7675,
18
(
6
), pp.
413
428
.
14.
Simo
,
J. C.
, and
Armero
,
F.
, 1992, “
Geometrically Nonlinear Enhanced Mixed Methods and the Method of Incompatible Modes
,”
Int. J. Numer. Methods Eng.
0029-5981,
29
, pp.
1595
1638
.
15.
Simo
,
J. C.
,
Armero
,
F.
, and
Taylor
,
R. L.
, 1993, “
Improved Version of Assumed Enhanced Strain Tri-Linear Element for 3D Finite Deformation Problems
,”
Comput. Methods Appl. Mech. Eng.
0045-7825,
110
, pp.
359
386
.
16.
Belytschko
,
T.
, and
Neal
,
M. O.
, 1991, “
Contact-Impact by the Pinball Algorithm With Penalty and Lagrangean Methods
,”
Int. J. Numer. Methods Eng.
0029-5981,
31
, pp.
547
572
.
17.
Belytschko
,
T.
,
Liu
,
W. K.
, and
Moran
,
B.
, 2000,
Nonlinear Finite Elements for Continua and Structures
,
Wiley
,
Chichester, UK
.
18.
Benson
,
D. J.
, and
Hallquist
,
J. O.
, 1990, “
A Single Contact Algorithm for the Postbuckling Analysis of Shell Structures
,”
Comput. Methods Appl. Mech. Eng.
0045-7825,
78
, pp.
141
163
.
19.
Mirza
,
U. A. A.
, 1999, “
Pile Short-Term Capacity in Clays
,”
Proceedings of the Ninth International Offshore and Polar Conference
, Brest, France, Vol.
I
, pp.
693
699
.
20.
Jeanjean
,
P.
, 2006, “
Set-Up Characteristics of Suction Anchors for Soft Gulf of Mexico Clays: Experience From Field Installation and Retrieval
,”
Proceedings of the 38th Offshore Technology Conference
, Houston, TX, Paper No. 18005.
21.
Eltaher
,
A.
,
Rajapaksa
,
Y.
, and
Chang
,
K. T.
, 2003, “
Industry Trends for Design of Anchoring Systems for Deepwater Offshore Structures
,”
Proceedings of the 35th Offshore Technology Conference
, Houston, TX, Paper No. 15265.
22.
Brandão
,
F. E. N.
,
Henriques
,
C. C. D.
,
Araújo
,
J. B.
,
Ferreira
,
O. C. G.
, and
Amaral
,
C. S.
, 2006, “
Albacora Leste Field Development—FPSO P-50 Mooring System Concept
,”
Proceedings of the 38th Offshore Technology Conference
, Houston, TX, Paper No. 18243.
23.
True
,
D. G.
, 1974, “
Rapid Penetration Into Seafloor Soils
,”
Proceedings of the Sixth Offshore Technology Conference
, Houston, TX, Paper No. 2095.
24.
Rowe
,
R. K.
, and
Davies
,
E. H.
, 1982, “
The Behaviour of Anchor Plates in Clay
,”
Geotechnique
0016-8505,
32
(
1
), pp.
9
23
.
You do not currently have access to this content.