Simplified Model for Suction Pile Stiffness under Combined Loading in Elastic Soil: A Winkler-based Approach

Suction pile foundations are a promising option for offshore structures in deep locations covered by soft soil. A reasonable prediction of foundation stiffness may offer a reliable method for estimating the dynamic performance of the overall structure. Although the Winkler-based approach can effectively analyze the stiffness of caisson foundations, the current models can underestimate and/or overestimate the global stiffness subjected to combined loading under a relatively large embedment depth-to-diameter ratio L / D . Moreover, the non-linear distribution of local stiffness with depth has been neglected in current research methods. Thus, this study established a simplified Winkler model capable of providing reliable predictions of suction pile foundation stiffness under combined loading in homogeneous elastic soil. Finite element analysis (FEA) was performed to establish inter-relationship of local stiffness with soil properties and foundation geometries via the concept of “Inferred Winkler model.” Furthermore, the non-linear distribution of local stiffness with depth was considered. Finally, the proposed method was assessed against the FEA and current models to evaluate its applicability with different L / D subject to general single and combined loadings.