Numerical study on long-term monopile foundation response

This paper analyzes the long-term monopile foundation that undergoes numerous mechanical cycles. The semiempirical scheme is adopted to involve a mechanical constitutive model to extract stress and strains at the first cycle and polynomial-type strain accumulation functions to track the progressive plastic deformation. In particular, the strain function contains the fundamental features that require simulating the long-term response of geomaterials: volumetric strain (terminal void ratio) and shear strain (shakedown or ratcheting), the strain accumulation rate, and stress obliquity. The numerical simulation shows evolution of displacements, pile rotation, and stress redistribution along the embedded pile as the number of load cycles increases. The analysis highlights that the pile rigidity affects the pattern of horizontal stress and displacement. The repetitive lateral load enhances the lateral load resistance due to soil densification along the pile.