Study of bearing capacity and failure envelopes of SEPLA under combined loading

The suction embedded plate anchor (SEPLA) has gained prominence as an effective anchoring solution for offshore floating platforms, owing to its precise installation capabilities and superior load-bearing efficiency. Most existing literature primarily focuses on SEPLA's uniaxial bearing capacities under vertical (V), horizontal (H), or moment (M) loading. However, during the keying process or under extreme environmental conditions, SEPLA is often subjected to complex combinations of vertical, horizontal, and moment (VHM) loads, which is the primary motivation for this study. Using the coupled Euler-Lagrange (CEL) method, this study conducts a comprehensive large deformation finite element analysis of SEPLA under various combinations of vertical, horizontal, and moment loads, both pairwise and simultaneously. The study aims to determine the failure envelopes for load-bearing capacity under different loading combinations. A parametric analysis of these failure envelopes under various combined loading planes is performed. The results show that the anchor embedment depth, even after normalization, significantly influences the shape of the failure envelope, while the effects of anchor shape and interfacial friction are largely eliminated through normalization. A closed-form equation is developed to approximate the three-dimensional failure surface that dictates SEPLA’s bearing capacities under combined VHM loading. The findings of this research contribute to expanding the database for plate anchor bearing capacity under combined loading and provide a rational framework for estimating SEPLA's load-bearing capacity in design applications.