Three-Dimensional Numerical Modeling of Drained Uplift Behavior of Rectangular Plate Anchors Using NorSand

Plate anchors offer an attractive anchoring solution for floating renewable energy devices in deep water, whereas the uplift behavior of plate anchors in sand and the associated failure mechanisms remain insufficiently explored. This study investigates the uplift behavior and the corresponding three-dimensional (3D) failure mechanisms of rectangular plate anchors in sand through finite element (FE) analysis. The critical state–based NorSand model, implemented in the FE package Abaqus/Standard, was employed to describe sand behavior. The FE model was validated against both element tests and centrifuge data. A parametric study was conducted to investigate the effects of relative density and embedment ratio on the uplift capacity of rectangular anchors in sand. The 3D failure mechanism of rectangular anchors in sand was revealed and discussed, with particular focus on the inclination angles of shear bands and the extent of the failure zone, which provide key parameters for improving the predictive capability of existing analytical solutions. Stress paths at representative positions within the failure zone were examined, revealing a progressive failure mechanism that is analogous to triaxial compression and simple shear loading modes. Based on the simulation results, the shape factor predictions for rectangular anchors were discussed, showing the conservatism (i.e., underestimation) of existing methods in medium-dense sand. Practical relations were further developed to provide FE-based shape factor estimates for the rectangular anchors investigated. The findings highlight the importance of considering the 3D failure mechanism in plate anchor design.