| Nowadays,with the renewable and clean wind power's widely being exploited,the offshore wind turbine developed rapidly.However,the offshore wind power in china are mostly built in the Circum-Pacific seismic belt area,which make it vulnerable to strong earthquake action caused by faults.With the increase of the offshore wind turbine capacity,the height of tower tube and the length of blade are increasing as well.The increase of structural flexibility reduced the natural frequency of the turbine,enlarged the influence of dynamic load on supporting structure,which will easily cause the quasi – resonance of turbine and finally lead to the damage.Located in the marine environment,the liquefaction of seabed soil and the dynamic water pressure caused by structural vibration further increases the safety risk of the turbine.In addition,offshore wind power system is a strong coupling system,which not only involves dynamic water,motion and inertial effects,but also is affected by many other factors,such as foundation,seabed and supporting structure.Therefore,considering system coupling,it is necessary to establish an analytical dynamic model of multi-system coupling offshore turbine for clarifying the mechanism of seismic response.Based on the background above,considering the pile-soil-tower tube-blade coupling,the seismic response of offshore turbine was studied.The main work are as follows:(1)Aiming at the seismic response of single pile foundation wind turbine under real earthquake,a model of pipe pile-soil-tower-engine-blades coupling wind turbine was established.Considering the liquefaction characteristics of soil and hydrodynamic pressures,distribution of peak horizontal displacement and internal force of single pile and tower tube was obtained.The liquefaction process under different seismic intensity was monitored.The effects of seismic intensity,pile diameter and seawater depth on seismic response of offshore turbine structures were analyzed.(2)Based on the single pile foundation above,the seismic response of offshore turbine with high cap inclined pile group foundation under real earthquake was calculated.The internal force distribution of each pile was analyzed.The seismic response of wind turbine with inclined pile group and straight pile group was compared,the influence of pile inclination on seismic performance of structure was analyzed.The deformation and internal force of wind turbine system under different ground layering conditions(including overlying soft and hard soil layer,soft and hard interlayer,overlying soft soil modulus)were analyzed.(3)Based on the offshore turbine model supported by high cap inclined pile group foundation,with three groups of near-fault impulse seismic waves and corresponding far field records as input time history,differences of dynamic response were compared quantitatively for these two kinds of earthquake ground motions.The development of internal force and deformation of wind turbine system under the action of near fault pulse seismic wave was analyzed.(4)Based on the Novak principle,considering free field fluctuation,pile top inertial load,flowing water pressure on pile and radiation wave field,the frequency-domain solution to the horizontal vibration of high pile-cap foundation turbine structure under homogeneous saturated soil under SH wave was obtained.The influence of pile spacing,top concentration mass,seawater depth,tower height,pile length-to-diameter ratio and soil elastic modulus on the resonance characteristics and displacement internal force distribution of the system was discussed. |
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