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Technical Brief

Effect of Fluke Inclination on Behavior of Drag Anchor in Uniform Clay Under Unidirectional and Combined Loading

[+] Author and Article Information
Xiaoni Wu

State Key Laboratory of Ocean Engineering,
School of Naval Architecture,
Ocean & Civil Engineering,
Shanghai Jiao Tong University,
Shanghai 200240, China
e-mail: wuxiaoni@sjtu.edu.cn

Yean Khow Chow

Centre for Offshore Research and Engineering,
National University of Singapore,
1 Engineering Drive 2, E1A-02-19,
Singapore 117576
e-mail: chowyk@nus.edu.sg

Chun Fai Leung

Centre for Offshore Research and Engineering,
National University of Singapore,
1 Engineering Drive 2, E1A-02-19,
Singapore 117576
e-mail: ceelcf@nus.edu.sg

1Corresponding author.

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received December 26, 2017; final manuscript received January 6, 2019; published online February 13, 2019. Assoc. Editor: Sungmoon Jung.

J. Offshore Mech. Arct. Eng 141(5), 054501 (Feb 13, 2019) (8 pages) Paper No: OMAE-17-1226; doi: 10.1115/1.4042534 History: Received December 26, 2017; Revised January 06, 2019

Prediction of trajectory of drag anchor is important for the design and selection of drag anchor. Prediction based on yield envelope characterizing the anchor behavior under combined loading provides a promising method. However, the existing application of the yield envelope method ignores the effect of the fluke inclination angle by assuming a horizontally placed anchor fluke. This study aims to investigate the behavior of inclined fluke, which is the practical case during installation. The effects of the fluke inclination angle and embedment depth ratio on the anchor behavior in uniform clay under unidirectional loading and combined loading are investigated. It is found that the effect of the fluke inclination angle on the unidirectional capacity factors is mainly for anchor with embedment depth ratio less than 3. This results in the large difference of the size of the yield envelopes for fluke with same smaller embedment depth ratio but different fluke inclination angle, while the effect is minor on the shape of the yield envelope for such cases. However, there is large difference in the shape and size of the shallow yield envelopes for fluke with different embedment depth ratios and inclination angles.

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References

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Figures

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Fig. 1

Anchor fluke geometry: (a) horizontal anchor fluke geometry and (b) inclined anchor fluke geometry

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Fig. 2

Schematic of FE model for capacity studies of horizontal anchor fluke

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Fig. 3

Vertical, horizontal, and rotational capacity factors for horizontal fluke with no breakaway interface at different embedment depth ratio: (a) vertical capacity factor, (b) horizontal capacity factor, and (c) rotational capacity factor

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Fig. 4

Effect of fluke inclination angle on the vertical and horizontal capacity factor for fluke with no breakaway condition

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Fig. 5

The soil failure mechanism for inclined fluke with β of 30 deg at HD/B of 1 with no breakaway interface: (a) fluke under vertical loading, (b) fluke under horizontal loading, and (c) fluke under rotational loading

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Fig. 6

The soil failure mechanism for inclined fluke with β of 30 deg at HD/B of 2 with no breakaway interface: (a) fluke under vertical loading, (b) fluke under horizontal loading, and (c) fluke under rotational loading

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Fig. 7

The soil failure mechanism for inclined fluke with β of 30 deg at HD/B of 4 with no breakaway interface: (a) fluke under vertical loading, (b) fluke under horizontal loading, and (c) fluke under rotational loading

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Fig. 8

Comparison of yield loci in normalized VH, VM, and HM spaces for rough fluke with β of 40 deg and 0 deg at HD/B of 1: (a) yield loci in VH space, (b) yield loci in VM space, and (c) yield loci in HM space

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Fig. 9

Comparison of shallow (HD/B of 1 and β of 40 deg) and deep yield loci (HD/B of 10 and β of 0 deg) from Wu et al. [11] in VH, VM, and HM spaces: (a) yield loci in VH space, (b) yield loci in VM space, and (c) yield loci in HM space

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Fig. 10

Comparison of yield loci from cases for fluke with β of 40 deg at HD/B of 1 and fluke with β of 30 deg at HD/B of 2 in VH, VM, and HM spaces: (a) yield loci in VH space, (b) yield loci in VM space, and (c) yield loci in HM space

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