Wave Run-Up on Offshore Windturbine Foundations

In the last decade, several offshore wind-farms are built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there still are some engineering challenges in placing the wind turbine foundations offshore. For example, unexpected damage to boat landing facilities and platforms has been caused by wave run-up and wave impacts on the platforms. To be able to assess the forces caused by the wave run-up, it is necessary to know the maximum run-up height and the destribution of the run-up along the pile. This article describes a physical model study investigating run-up heights and run-up distribution on different offshore windturbine foundations due to regular and irregular waves. The influence of wave steepness, wave height and water depth on the run-up on a monopile foundation is investigated. The run-up on a cone foundation is compared with the run-up on a monopile foundation. A comparison is made between the measured run-up values and several theories and previous experimental studies which predict the run-up on a circular pile. A new suggestion for a relatively simple relationship between the wave climate and the run-up is made, both for regular and irregular waves. Finally, a special interest is made on distribution of run-up along the pile and the location of the point of minimum run-up.