Failure-Mechanism and Design Techniques of Offshore Wind Turbine Pile Foundation: Review and Research Directions

Wind energy is one of the most sustainable and renewable resources for power generation. Offshore wind turbines (OWTs) derive significant wind energy compared to onshore installations. One of the greatest challenges encountered by installing the OWTs is the adequate design of their foundation in relatively soft and compressible marine soil. In most cases, the OWTs are supported by a single pile, termed as 'monopile foundation'. Apart from the usual loads from the superstructure, these piles are subjected to complex loading conditions under static and cyclic modes in the axial, lateral, and torsional directions due to the primary actions of the wave, wind, and current. To incorporate an appropriate design methodology, understanding the failure mechanisms of such piles is of the utmost necessity. This review paper aims to focus on the progressive development in the analysis of failure mechanisms and design practice relevant to the monopile foundations for OWTs by theoretical and experimental studies conducted globally. An extensive literature survey has been carried out to study the gradual progress on offshore pile-soil interaction, failure mechanisms, and design techniques of OWT supporting monopile foundations. Based on the studies, a brief overview of the various aspects of analysis and design has been carried out, and the relevant conclusions are drawn therefrom.