Mechanical Response of Kaolin Clay Subject to Cyclic Loading with Time-Varying Direction

Abstract Offshore wind energy is increasingly moving toward floating structures in deeper waters, where shared anchoring systems offer significant cost reduction potential by minimizing anchor usage. However, such anchors experience complex multidirectional cyclic loading during extreme events such as typhoons, where both intensity and direction of loads evolve over time. Current design standards account only for unidirectional cyclic loading, creating a critical knowledge gap for shared anchor design. This study investigates the behavior of normally consolidated clay subjected to cyclic shearing with time-varying direction through a series of direct simple shear (DSS) tests. Results show that evolving load direction accelerates soil failure under nonsymmetric cyclic loading but has limited effect in symmetric conditions. The detrimental impact intensifies with higher average shear stress levels and greater total directional changes. Permanent shear strain accumulation is ahead of the shear stress direction by approximately 30° in nonsymmetric tests. These findings provide essential insights into soil response under multidirectional cyclic loading, supporting the future development of design methodologies for shared anchor systems in floating offshore wind farms.