Abstract
Suction caisson anchors are widely employed in floating offshore wind systems; however, their capacity under earthquake-induced liquefaction remains limited, emphasizing the need for a reliable design framework. This study develops a predictive framework to quantify suction anchor pullout capacity under liquefaction, accounting for seismic variability and varying liquefaction depths. Three-dimensional finite element analyses were conducted using the UBC3D-PLM constitutive model to investigate soil liquefaction. The failure envelope equations (VH) were developed using second-order polynomial functions considering the L/D ratio of anchor, normalised liquefaction depths (h/L), and excess pore pressure ratio (ru). Partial liquefaction was incorporated through the number of uniform loading cycles required to reach liquefaction at a specified cyclic stress level. Large-diameter anchors undergo the most severe capacity degradation, while smaller anchors sustain comparatively higher resistance at equivalent liquefaction depths. The study provides a practical framework for assessing the suction anchor capacity under liquefaction, contributing to safer and more reliable floating offshore foundation designs.
•Smaller-diameter anchors require deeper optimal padeye positions than larger anchors.•Liquefaction reduces anchor pullout capacity by 45–79%.•Failure-envelope equations are developed for partial-liquefaction conditions.•Slender anchors provide better capacity retention under liquefaction.•A practical case study demonstrates suction-anchor capacity for floating wind turbines under liquefaction.