| The frequency-domain response of the horizontal vibration of the pilesupported offshore wind turbine is the theoretical basis for analyzing the resonance characteristics and seismic response of the turbine system.Considering the complexity of the marine environment,the great majority of the existing scientific research achievements are carried out on such single system as the dynamic characteristics of wind turbine tower and dynamic interaction between foundation and homogeneous seabed soil.In practice,the seabed soil,in the actual condition,is often heterogeneous along the depth or radial direction.In addition,the wind turbine may suffer from complex environmental loads,for instance,earthquake,wave and wind loads while its running.Therefore,based on the Biot wave equation of saturated soil,this paper considering the coupling effect of pilesoil-tower establishes a theoretical analysis model of horizontal dynamic characteristics of pile supported offshore wind turbine system under the incidence of SH wave,which is on the basis of the existing research results.Then,the main research contents,in this paper,include the following three aspects:(1)Based on Biot wave theory,the horizontal dynamic impedance of the soil around the pile(core)in saturated seabed soil under the action of SH wave can be calculated,and the horizontal vibration equation of the pile can be established.Moreover,the Morison equation is used to consider the dynamic hydraulic pressure of the immersed section of the pile,and the tower is regarded as a variable section beam.Final,based on the general solution of the linear differential equation of the variable coefficient of the tower and the continuity condition of the adjacent section,the theoretical calculation model of horizontal dynamic response of seabed-pipe pile-fan structure system is established when the harmonic SH seismic wave is incident.On the basis of the above,the system parameters can be further analyzed affecting resonance characteristics and dynamic amplification coefficient of wind turbine system.(2)Based on the principle of Novak and the principle of radiated wave propagation,the horizontal displacement attenuation function in the layered saturated seabed can be obtained;and then the partially buried pile-soil-pile dynamic interaction factor under the action of the overlying fluid layer is obtained;Group piles and towers can be combined to calculate through the principle of displacement superposition and the balance of force at the platform;finally,the horizontal vibration problem of the partially buried group pile-platform-tower structure system can be solved in the layered saturated seabed and frequency domain under the SH wave.Finally,the effect of parameters on the system’s resonance characteristics and internal force distribution of displacement can be analyzed such as pile layout,pile spacing,water depth,tower height,etc.(3)Based on the Winkler foundation beam model,considering the nonlinear variation of the shear modulus of the saturated seabed soil in the radial direction,the radial(circular)directions of the inner and outer ring soil areas and the pile core soil of the saturated seabed soil are obtained by decoupling Biot equation.On this basis,the horizontal resistance of the radial heterogeneous soil layer to the pile foundation is calculated,and the expression of the horizontal displacement of the pile foundation is solved considering of the radial nonlinear soil-pile interaction.Then,the upper wind turbine tower structure was contacted to establish a horizontal dynamic response research model of the marine fan in the radial heterogeneous saturated seabed soil under SH wave incidence. |
PDF Full Text Request