Anchor and Chain Reaction During Inclined Pullout in Clay

Abstract

Plate anchors have attracted much attention in offshore deep water development. This paper studies anchor rotation and chain reaction during plate anchor inclined pullout when it is installed vertically in clay. Both numerical simulation of strip plate anchor and centrifuge model tests on square anchor are conducted in uniform and normally consolidated (NC) clay. In the numerical analysis, Remeshing and Interpolation Technique with Small Strain model (RITSS) is used to simulate large movements of the anchor. In the centrifuge model tests, a transparent “soil” is used to observe anchor rotation and chain reaction during anchor pullout. It is found that plate anchors reach ultimate capacity (Nc ≈ 11.7) when they are fully rotated to a position perpendicular to the pullout direction. During anchor pullout at 60° to the horizontal, the loss of embedment during keying-in ranges from 0.38 B to 0.58 B for square and strip anchors in uniform and NC soils. The loss of anchor embedment in NC clay is about 4% ∼ 23% higher than that in uniform clay depending on the soil strength profile in the NC soil.