Response of Anchor in Two-phase Material under Uplift

Anchors are foundation systems used to withstand uplift forces acting on to the foundations of structures constructed both in land and offshore. Numerous methods were developed to design anchors embedded in varieties of deposits. In most of the existing methods, the two-phase response of soil is not represented adequately. Moreover, contribution to anchor capacity through suction and influence of upward seepage flow are not quantified particularly for anchors embedded in submerged sand. In order to bring out the effect of two-phase material on load-displacement response and ultimate pullout capacity, an attempt is made in this research to analyse the anchor using the finite element code PLAXIS. Depth of embedment, relative compactness of sand and seepage velocity are the variables considered in the study. Finite element analyses showed distinctly two different responses namely shallow and deep anchor behaviour. Load- displacement curves are interpreted to arrive at the ultimate pullout load and thus the breakout factors which are in good agreement with the experimental results reported in literature.