Developing an Optimal Shape for Dynamically Installed Anchor

Abstract Dynamically installed anchors (DIAs) have been identified as the most cost-effective anchoring solutions for mooring floating facilities because of its simple (free-fall) installation procedure. Due to the impressive concept of DIAs, many attractive shapes of the anchor have been proposed. However, the influence of the various geometric parameters on the performance of the anchor during installation and under operational loadings is yet to be explored. This paper assesses the potential of changing each component of the geometry and through that optimising the shape aiming at reducing fabrication cost and increasing efficiency in terms of tip embedment depth during installation and diving behavior under operational loadings. Large-deformation finite element analyses were performed using the Coupled Eulerian-Lagrangian (CEL) approach with the simple elastic-perfectly plastic Tresca soil model modified incorporating strain softening and strain-rate dependency of the shear strength. Parametric analyses were conducted varying the configurations of the shaft, fins and padeye. The anchor drag coefficient during free-fall in the water column was also assessed through computational fluid dynamics (CFD) analyses. Thus far, it has been found that an anchor with (i) a 1:2 sloped cylindrical shaft, (ii) padeye offset ratio within 0.2 < ηp < 1, and (iii) enhanced middle main two fins show better performance in terms of tip embedment depth and diving upon loading. A critical factor to dive is the alignment of the loading direction at the padeye with the anchor resistance centroid.