An Elastoplastic Model for Predicting Kinematics and Trajectories of Suction-Embedded Plate Anchors under Eccentric Loading in Clay

Abstract

Previous plasticity models for predicting anchor kinematics under eccentric loading in clay are mostly rigid plastic. They may produce inaccurate outcomes in some conditions. This paper presents an elastoplastic model to address this issue. Closed-form solutions for anchor velocities are derived considering two types of boundary conditions: the padeye (1) fastened to a mooring chain, with the chain behavior modeled; or (2) hinged to a rigid rod. Compared with previous methods, the proposed method more realistically captures the soil behavior while avoiding complicated iterative procedures for solving anchor velocities, thus enabling anchor trajectories to be accurately and efficiently obtained by simple time integration. A series of 3D large deformation finite element analyses are conducted to study the anchor behaviors under different eccentric loading, and the proposed model is used to reproduce these simulations. Their results are compared for validation, with good agreements achieved. These results indicate that anchors under eccentric loading will ultimately translate along a fixed direction with constant soil reaction forces. Analytical solutions for this ultimate state are given based on the proposed method. Particularly, the ultimate resultant soil reaction force is demonstrated always passing through the anchor center. This is an assumption in a previous literature but is found to be a consequence of the proposed anchor constitutive relations.