Vertical Pull-Out Capacity of Torpedo Anchors

  • S. Keerthi RaajEmail author
  • R. Sundaravadivelu
  • Nilanjan Saha
Conference paper
Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 22)


In recent years, the novel concept of dynamically installed anchors like torpedo-shaped anchors has a significant development in offshore gas exploration and platform construction. Torpedo anchors are those which breach to the designated embedment depth by the kinetic energy acquired in the process of free fall and develop vertical as well as horizontal pull-out resistances. The large scale of uncertainties in pull-out capacity theoretical prediction often requires a finite element analysis. Hence, this paper investigates the vertical pull-out resistance offered by torpedo pile anchors through numerical simulation using PLAXIS. The kaolin clay soil properties are assumed, and modified cam clay (MCC) soil model is assigned throughout the entire numerical simulation. The cylindrical-shaped torpedo pile anchor was modelled with “wished in place” configuration as zero fin, blunt tip with four different aspect ratios (\(l/d\) = 5, 10, 15, 30), and each anchor is analysed under four different embedment depths to anchor height ratios (\({D/l}\) = 2, 2.5, 3, 3.5). The effects of embedment ratio and aspect ratio and their influence on the anchoring capacity were studied, and the numerical results are validated through the established empirical results. The pull-out capacities of the anchors are further studied for varying disturbed zone diameter of (1D, 2D, 3D and 4D). And hence, it is concluded that the character of the remoulded soil significantly influences the vertical pull-out resistance and the extent of remoulded soil zone due to anchor penetration is between 3D to 4D.


Torpedo pile anchors Pull-out capacity Embedment depth PLAXIS 



The authors are thankful to acknowledge the support from the Department of Ocean Engineering and Department of Civil Engineering, Indian Institute of Technology, Madras, for authorizing the work described here to occur.


  1. 1.
    Schmid WE (1969) Penetration of objects into the ocean bottom (the state of the art). Technical Report AD0695434. Naval Civil Engineering Laboratory, Port Hueneme, CaliforniaGoogle Scholar
  2. 2.
    Medeiros CJ (2002) Low cost anchor system for flexible risers in deep waters. Offshore Technology. Offshore Technology Conference, Texas U.S.A.
  3. 3.
    Pecorini, D., and De, A.: Pull-Out Capacity Analysis of Offshore Torpedo Anchors Using Finite-Element Analysis, International Society of Offshore and Polar Engineers, Hawaii, USA. ISSN 1098-6189 (2015)Google Scholar
  4. 4.
    O’Loughlin CD, Randolph MF, Richardson M (2004) Experimental and theoretical studies of deep penetrating anchors. In: Offshore technology conference, Texas, USA.
  5. 5.
    Lieng JT, Hove F, Tjelta TI (1999) Deep penetrating anchor: subseabed deepwater anchor concept for floaters and other installations. In: The ninth international offshore and polar engineering conference. International Society of Offshore and Polar Engineers, Brest, FranceGoogle Scholar
  6. 6.
    Beard RM (1984) Expendable Doppler penetrometer for deep ocean sediment strength measurements. Technical Report R-905. Naval Civil Engineering Laboratory, Port Hueneme, CaliforniaGoogle Scholar
  7. 7.
    Robertson RM (1965) Expendable instrumentation. In: Knopf WC, Cook HA (eds) Marine sciences instrumentation, vol 3. Plenum Press, New York, pp 99–121Google Scholar
  8. 8.
    Scott RF (1970) In-place ocean soil strength by accelerometer. Proc Am Soc Civil Eng J Soil Mech Found Div 96:199–211Google Scholar
  9. 9.
    Dawson PR, Chavez PF (1978) Seabed waste disposal program: one-dimensional hole-closure simulation: SAND 78-1275. Sandia National Laboratories, AlbuquerqueCrossRefGoogle Scholar
  10. 10.
    Lott D, Poeckert RH (1996) Extending co-operative research: Canada, New Zealand, United States in joint effort in British Columbia to evaluate penetrometers for ground truthing acoustic classifiers for mine countermeasures. Sea Technol 56–61Google Scholar
  11. 11.
    Soh BP, Pao W, Al-Kayiem HH (2015) Numerical analyses for improved hydrodynamics of deep water torpedo anchor. In: OP conference series: material science engineering, vol 100. Scholar
  12. 12.
    Wang W, Wang X, Yu G (2016) Penetration depth of torpedo anchor in cohesive soil by free fall. Ocean Eng 116, 286–294. ISSN 0029-8018. Scholar
  13. 13.
    Ehlers CJ, Young AG, Chen J (2004) Technology assessment of deepwater anchors. In: Proceedings of 36th annual offshore technology conference, Houston, Texas, Paper No. OTC 16840Google Scholar
  14. 14.
    Raie MS, Tassoulas JL (2009) Installation of torpedo anchors: numerical modeling. J Geotech Geoenviron Eng 135:1805–1813. Scholar
  15. 15.
    American Petroleum Institute (2002) Recommended practice for planning, designing and constructing fixed offshore platforms—working stress design. API RP 2A-WSD, Washington D.C., USAGoogle Scholar
  16. 16.
    O’Loughlin, CD, Richardson MD, Randolph MF (2009) Centrifuge tests on dynamically installed anchors. ASME. In: International conference on offshore mechanics and arctic engineering, vol 7: Offshore geotechnics; petroleum technology, pp 391–399.
  17. 17.
    Raie MS (2009a) A computational procedure for simulation of torpedo anchor installation, set-up and pull-out. Ph.D. thesis, The University of Texas at AustinGoogle Scholar
  18. 18.
    Sturm H, Lieng JT, Saygili G (2011) Effect of soil variability on the penetration depth of dynamically installed drop anchors. In: Offshore technology conference, Rio de Janeiro, Brazil.

Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Indian Institute of TechnologyChennaiIndia

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