Vertically loaded plate anchors for deepwater applications

Murff, James D.; Randolph, Mark; Elkhatib, Sarah; Kolk, H.J.; Ruinen, Roderick; Strøm, Pål Johannes; Thorne, Charles H.

doi:10.1201/noe0415390637.ch2

Cited by 48 publications

(29 citation statements)

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“…However, although the holding capacity of an anchor in the normal direction is reasonably established in soil of a given shear strength (Murff et al, 2005;Elkhatib, 2006;Wang et al, 2006;Song et al, 2008), uncertainty exists in the extent to which the anchor moves upward during keying (Song et al, 2009). Loss of embedment during keying has a significant effect on the design capacity.…”

Section: Introductionmentioning

confidence: 99%

A plasticity model to assess the keying of plate anchors

Cassidy¹,

Gaudin²,

Randolph³

et al. 2012

Géotechnique

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Suction-embedded plate anchors (SEPLAs) have been developed to answer the growing need for anchors to withstand significant vertical loading. The concept combines the advantage of suction caissons (known penetration depth and location) and 'drag-embedded' plate anchors (efficiency and low cost). The main issue associated with SEPLAs relates to the keying process, as the anchor is first loaded, and the associated loss of embedment and reduction in capacity. The paper presents a plasticity model developed to predict the trajectory and load development during anchor keying, and up to peak load. Rigid plasticity is assumed, allowing the kinematics of the anchor to be determined from a yield surface and associated plastic potential. The trajectory and performance of a typical SEPLA are predicted using the model, and are compared with results from centrifuge tests and large-deformation finite-element analysis. The anchor loss of embedment ranged from ,0 . 2 to 1 . 5 times the anchor height for loading inclinations between 408 and 908 from the horizontal. The model was used further to calculate the anchor loss of embedment and capacity for varying padeye offsets. Results indicated that the loss of embedment could be reduced significantly by increasing the offset, but at the detriment of the ultimate anchor capacity.

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Section: Introductionmentioning

confidence: 99%

A plasticity model to assess the keying of plate anchors

Cassidy¹,

Gaudin²,

Randolph³

et al. 2012

Géotechnique

View full text Add to dashboard Cite

show abstract

“…Plate anchors are an economic and efficient deep-water mooring solution, which have been used increasingly in recent years (Dove et al 1998;Murff et al 2005;Yang et al 2012). One popular installation method is to use a suction caisson housing the plate anchor to penetrate it to its designed depth.…”

Section: Introductionmentioning

confidence: 99%

Influence of padeye offset on bearing capacity of three-dimensional plate anchors

et al. 2015

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This paper reports advanced three-dimensional large-deformation finite element analyses investigating the effect of the padeye offset on the behaviour of plate anchors. The analyses varied the normalized padeye offset from 0 to 0.5 and identified two counterbalancing effects on the anchor bearing capacity induced by the padeye offset. These are the change in anchor inclination with respect to the direction of loading (detrimental due to the reduction of bearing area) and the reduction of loss of embedment (beneficial, as the anchor mobilizes stronger soil). The results provide insights to optimize the design of plate anchors. The underlying concepts also have applications for other types of anchors.Key words: plate anchor, large-deformation finite element analysis, clays, offshore engineering, loss of embedment, bearing capacity.Résumé : Cet article présente des analyses par éléments finis avancées en trois dimensions et en grande déformation servant à étudier l'effet de l'espacement des mains de fer sur le comportement des ancrages à plaque. Les analyses ont fait varier l'espacement normalisé des mains de fer de 0 à 0,5 et a identifié deux effets contre-balanciers sur la capacité portante des ancrages causés par l'espacement des mains de fer. Il s'agit de la variation de l'inclinaison de l'ancrage selon la direction de la charge (effet négatif dû à la réduction de la surface portante) et de la réduction des pertes d'enfouissement (bénéfique puisque l'ancrage mobilise un sol plus fort). Ces résultats offre des informations pour optimiser la conception des ancrages à plaque. Les concepts de base ont aussi des applications pour d'autres types d'ancrage. [Traduit par la Rédaction]Mots-clés : ancrage à plaque, analyse par éléments finis en grande déformation, argiles, ingénierie en mer, perte d'enfouissement, capacité portante.

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“…A hypothetical case study reported by Murff et al [1] revealed that significant deviations occurred among different prediction results. This sufficiently indicates that there are still uncertainties in predicting the kinematic trajectory adopting the generallyused numerical iterative methods, and prediction of the kinematic trajectory is still a great challenge for drag anchors.…”

Section: Introductionmentioning

confidence: 96%

“…Although a number of analytical and numerical studies more or less relevant to the above problems can be found in the literature [1][2][3][4][5][6][7][8][9], the relative experimental investigations, through 1 g lab tests or centrifuge programs, are limited and can be summarized as follows.…”

Section: Introductionmentioning

confidence: 99%