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

Abstract

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.

On the instability of offshore foundations: theory and mechanism

“…It was noticed that, unlike expected, the flap did not rotate during the keying process but rotated at the end of the keying. The shearing force was balanced by the soil bearing pressure at the back of the flap during the keying process [98]. However, the presence of the flap was beneficial to reduce the loss of embedment due to padeye offset to the center of the whole anchor [99].…”

Large deformation finite element analyses in geotechnical engineering

“…The advantage of RITSS is that the remeshing and interpolation strategy can be coupled with any standard FE program, such as the locally developed program AFENA [7] and the commercial package Abaqus/Standard, through user-written interface codes. The potential of the approach has been highlighted by varied two-dimensional (2D) and three-dimensional (3D) applications of monotonic and cyclic penetration of penetrometers [19,52], penetration of spudcan foundations for mobile jack-up rigs [16,17,51], lateral buckling of pipelines [49,8] and uplift capacity and keying of mooring anchors [31,[43][44][45]47,38,39]. More recently, RITSS was extended from static to dynamic analyses [48].…”

Analytical solution for ultimate embedment depth and potential holding capacity of plate anchors

“…For SEPLAs and DEPLAs, and indeed other anchors that are pre-installed, the anchor rises during the keying process, and design attention has focused on the embedment loss before the anchor achieves its maximum holding capacity Song et al, 2009;Wang et al, 2011;Cassidy et al, 2012;Yang et al, 2012;Tian et al, 2014d). However, with careful choice of geometry pre-installed anchors can be designed to 'dive'in other words, to embed deeperafter an initial loss of embedment (Shelton, 2007;Zimmerman et al, 2009;Tian et al, 2014a).…”

“…Aubeny et al, 2008;Aubeny & Chi, 2010Cassidy et al, 2012;Yang et al, 2012) or numerically (Song et al, 2009;Wang et al, 2011;Tian et al, 2014bTian et al, , 2014cTian et al, , 2014d, to establish the anchor travel trajectory and eventually the ultimate embedment depth. Instead, this paper proposes a much simpler analytical solution, which allows the ultimate embedment depth, and hence the potential holding capacity, to be calculated directly without simulating the whole process.…”

“…The increase of padeye offset ratio η results in greater sliding component N s and a smaller normal component N n . Consequently, the anchor failure mechanism tends to transit from a full flow around pattern (η ¼ 0) to a pure sliding pattern (η ¼ ∞) (seeTian et al (2014d) for further explanations). Also shown in the figure is the…”