The Experimental Study Of Wave Forces On The Stationary Pile-supported Structures For Offshore Wind Turbine

With the rapid expansion of offshore wind power industry,the wind power has been the pillar industry of new energy development.The stability of wind turbine's foundation structures plays a critical role in the safe operation of offshore wind farm.The high requirement for the wind turbine's foundation structures,and the complex and severe ocean environment in reality,make the research of wave loads on offshore wind turbine's pile-supported structures valuable in engineering and economy.For several typical pile-supported structures,including monopile,multi-piles with single pillar structure and high-rise pile cap,a series of physical model experiments in regular and irregular waves were conducted.Through analyzing the relationships between the experimental results of wave forces,wave elements and the characteristic geometric scales of pile-supported structures,an equivalent diameter was proposed.Unified empirical equation of wave forces for both monopile and complex pile-supported structures in regular and irregular waves was obtained,and empirical equations for different characteristic values of wave loads on complex pile-supported structures in irregular waves were proposed.The variations of pile group effect coefficients were investigated on the basis of the empirical formulas for wave forces.The difference of experimental pile group effect coefficients in time-domain and frequency domain were summarized.The relations of the force spectrum along wave direction,the horizontal force spectrum and the wave spectrum for different complex pile-supported structures were discussed.Besides,with the consideration of inclined piles and the phase displacements,the characteristic values of wave forces on the three-piles with single pillar structure and six-piles with single pillar structure were calculated by Morison equation,and the complexity of the process and the reliability of the results were analyzed.In the aspect of numerical simulation,the computational results from numerical wave flume were compared with the empirical equations of wave forces,and the validity of empirical equation was further verified.