Pile run refers to the phenomenon that occurs during the installation of pile and monopile foundations in soils with low bearing capacity, where soil resistance is insufficient for the controlled driving of the monopile. The increasing frequency and associated risks of such occurrences in offshore installations underscore the necessity for effective pile run mitigation strategies.

This thesis investigates the feasibility of utilizing a mitigation structure to reduce pile run during the impact driving of monopile foundations. The primary objective is to model and analyze the dynamics of the hammer-pile-soil system under impact driving and pile run, with a focus on the impact of a mitigation tool in monopile response.

The research adopts a structured methodology, beginning with a qualitative study to identify effective mitigation measures. A 1-D finite element (FE) model is developed to simulate pile run, while a 2-D FE multiphysics model characterizes the fluid-structure interaction (FSI). The study explores the effects of various geometric parameters of the mitigation structure on forces and stresses experienced during pile run.

Key findings indicate that the implementation of a mitigation structure can significantly reduce pile run velocity, with its performance being influenced by the geometry of the structure and the velocity of the pile. A trade-off exists between velocity reduction and maintaining structural integrity. The research also highlights the critical role of FSI in determining the structural response of the mitigation tool and its interaction with the monopile.

Conclusions drawn from the results suggest practical applications for the mitigation measure, emphasizing the need for further investigation into the design and deployment mechanisms of the structure. Recommendations for future research directions are provided, aiming to enhance the understanding and application of pile run mitigation strategies in offshore engineering practices.