A Unified Model for Analyzing Comprehensive Behaviors of Deepwater Anchors

Abstract

Anchors may exhibit various complicated behaviors in the seabed, especially for deepwater anchors including gravity installed anchors (GIAs) and drag embedment plate anchors (drag anchors), stimulating the development of an efficient analytical tool that applies to a variety of anchors. The present paper introduces a unified model for analyzing different anchor behaviors in both clay and sand, consisting of unified concepts, mechanical models, and analytical procedure. The kinematic behaviors of the anchors are classified uniformly as three types, i.e., diving, pulling out, and keying. By utilizing the least-force principle, various anchor properties, such as the ultimate pullout capacity (UPC), failure mode, movement direction, embedment loss, and kinematic trajectory, can all be determined by the combination and analysis of the three behaviors. Applications of the model are demonstrated summarily, by solving the UPC and the failure mode of anchor piles and suction anchors, the kinematic trajectory of drag anchors in a single soil layer or layered soils, the maximum embedment loss (MEL) of suction embedded plate anchors (SEPLAs) and OMNI-Max anchors, and the kinematic behavior of OMNI-Max anchors. Compared to existing theoretical methods, this unified model shows strong applicability and potentiality in solving a variety of behaviors and properties of different anchors under complicated seabed conditions.

Instability and Failure of Subsea Structures

“…A unified model was introduced in [8] to analyze the comprehensive behaviors of deep-water anchors in both clayey and sandy seabeds, including unified concepts, mechanical models, and analytical procedures. By utilizing the least-force principle, various anchor properties, such as the ultimate pullout capacity, failure mode, movement direction, embedment loss, and kinematic trajectory, can all be determined using the combination and analysis of three behaviors, i.e., diving, pulling out, and keying.…”

Failure Behavior and Surrounding Soil Stress Responses of Suction Anchor in Low-Strength Muddy Clay

“…Installing a suction anchor is both cost-effective and convenient compared to piling in deep water, and a suction anchor can provide high bearing capacity. Suction anchors with taut wire have excellent stability and high deformation control accuracy, which can be used to tension leg oil platforms [4], floating wind turbines [5,6], and submerged floating tunnels [7].…”

“…For the bearing capacity under static load, the previous research pays more attention to the length/diameter ratio (L/D) [2] and mooring position [24] of suction anchors, which significantly influences the bearing capacity. The mooring position, which ensures that the anchor purely translates, is known as the optimal loading point of suction anchors (i.e., when a horizontal or inclined load is experienced) [4]. However, loading on the optimal point is ideal.…”