Pullout behavior of suction anchors in soft marine clays

Abstract

In the field of ocean engineering, a beginning has been made in the use of large‐sized suction anchors for safe anchoring of large compliant structures. Suction anchors derive most of their uplift resistance from passive suction developed during the pullout movement. This article describes a set of laboratory tests on model suction anchors of three different embedment ratios to estimate the pullout behavior of suction anchors in soft clays typical of Indian marine clays. Tests were conducted on model anchors installed in soil beds prepared at four different consistencies in a test tank. This study shows the influence of soil consistency and embedment ratio (L/D) on the pullout behavior of suction anchors and on the variation of suction pressure at the top of the soil plug. The test results reveal that the behavior of suction anchors is much better than the behavior of open‐ended anchors from the considerations of both capacity and deformation. The consistent development of suction inside the anchor top confirms the plug formation and significant breakout resistance in the form of suction‐induced reversed end bearing. The results are further analyzed in terms of suction breakout factors. Further, the effect of burial depth of suction anchor on pullout behavior is shown.