STUDY ON THE MONO-PILE FOUNDATION OF OFFSHORE WIND TURBINE BY USING P-Y CURVE

Abstract

By the environmental pollution, global warming and resource depletion owing to the utilization of fossil fuel, various green energies has been recently in the spotlight. Of these, interest in the wind energy has been increased since the high quality wind resources are obtained both in onshore and offshore. Wind, the driving force for the wind power generation as one of the green energies, is observed higher quality value in the offshore than that of onshore. Also, the development of offshore wind towers has been in the spotlight as an alternative method in order to solve the problems of onshore wind farm such as securing sites, noise, and electromagnetic waves, and in order to get efficient wind power energy. Therefore, the many researches on offshore wind energy have been carried out. As wind towers are advanced to ocean, offshore wind towers have been enlarged. Also, various external forces such as wave force and collision of vessel and tidal current, act on offshore wind tower. Thus, the stability of offshore wind tower is required to endure wind force and wave force. Mono-piles are often applied as foundations for offshore wind tower at water depths less than 30m. In this type of foundation, subsoil conditions affect to endure external force. The various soil conditions make different soil reaction and displacement. In this study, the external forces act on the foundation. And the calculation is carried out, for the various soil conditions such as cohesive soil, sandy soil and multi-layered. The wave force is calculated by Morrison's equation, and thrust force is analyzed by BEMT(Blade Elemental Momentum Theory). Using computed external forces, displacement of offshore wind tower and subsoil reaction are calculated. As a result, the understanding of the stability in offshore wind tower with various soil conditions is improved, and the various soil conditions are considered for the safety evaluation.