Installation and capacity performance of multi-line dynamically installed anchors

Abstract

The multi-line anchor achieves the ‘anchor sharing’ goal by allowing multiple floating devices to be moored, such that the total number of anchors in a floating device array can be reduced significantly. This study proposes a dynamically installed anchor with the potential of resisting uplift loads from varied directions. The multi-line anchor is dynamically installed with the aid of a booster. The installation performance of the hybrid anchor (i.e. multi-line anchor + booster) is first examined by field tests. Then finite-element analyses are performed to investigate the uplift capacity of the anchor under V-H-M-T combined loading conditions. Based on the numerical results, yield envelopes are established for assessing the ultimate bearing capacity of the anchor. Additionally, model tests are conducted to quantitatively study the installation and set-up effects on the uplift capacity of the anchor, indicating the vertical and torque capacities are sensitive to the installation effect. Finally, a design framework is proposed to assess the stability of the multi-line anchor under combined loading conditions.