Analytical Model for Vertically Loaded Anchor Performance

Abstract

Vertically loaded anchors (VLAs) are installed in a manner similar to drag-embedded anchors, except that after initial drag installation the anchor shank is released to enhance pullout capacity. Because of their lightness and relatively low installation cost, VLAs offer an attractive alternative for mooring systems. However, existing design procedures are largely empirically based, and uncertainties with regard to anchor trajectory and load capacity have limited their application to temporary mooring systems. This paper presents a design model for predicting VLA performance during drag installation, shank release, and subsequent loading beyond the installation load. Model-based parametric studies on the effects of VLA fluke–shank angle and anchor line angle at the mudline are also presented. Some aspects of the model have been benchmarked against limited available field data, but a broader validation is still needed.