风浪流共同作用下海上风电基础与海床的动力响应分析

我国近海风资源丰富,但由于海洋环境条件的复杂性,开发利用近海风资源的规模和效益受到很大的制约;而风、波浪和海流等作为近海主要环境荷载对近海风机的正常运行起到决定性作用。采用谐波叠加法模拟得到近海风电场的风荷载时程,利用Morison方程和非线性波浪理论推导了波浪荷载和波流荷载的计算公式,最后根据Turkstra准则将风浪流荷载进行叠加组合,建立风浪流荷载共同作用下海上风电基础与海床动力相互作用的三维有限元计算模型。基于此模型,针对不同荷载组合条件下风机塔筒的水平位移、竖向应力以及基础的水平位移、桩身弯矩、桩身剪力等进行了动力分析,同时对风浪流荷载共同作用下桩基础周围海床的超孔隙水压力响应进行了计算分析,讨论了不同的荷载参数对海床超孔隙水压力的影响。结果表明:风荷载对风机塔筒顶端水平位移、塔底应力影响较大,波流荷载对风机基础顶端水平位移、桩身弯矩、桩身剪力影响较大,而波浪荷载则对海床孔隙水压力影响较大。可取最大风荷载和最大波流荷载叠加波浪荷载时程的组合为最不利组合方式。

Dynamic Response Analysis of Offshore Wind Power Foundation and Seabed under the Combined Wind, Wave and Current Loadings

Wind resources are rich in offshore areas of China, but the scale and efficiencyof developing and utilizing offshore wind resources are greatly restricted dueto the complex conditions of marine environment conditions. As the main environmental loads, wind, wave, and current play a decisive role in the normal operation of offshore wind turbines. In this paper, the time history of an offshore wind farm is simulated by using the harmonic superposition method, and the formula for calculating wave and current loadings are derived based on the nonlinear wave theory andthe Morison equation. Then, the wind, wave, and current loadings are combined according to the Turkstra criterion. Based on the above theories, a three-dimensional finite element model for dynamic interaction of offshore wind power foundation and seabed is established under the combined wind, wave and current loadings. Based on this model, the dynamic horizontal displacement, the vertical stressof wind turbines tower, and the horizontal displacement, bending moment and shear force of the foundation are analyzed under different loading combinations. Moreover, the excess pore pressure response of seabed around the pile foundation isexamined under the combined action of wind, wave, and current loadings. Finally, the influence of different load parameters on the excess pore water pressure of seabed is discussed. It can be concluded from the computation results that thewind loading has a great influence on the horizontal displacement at the towertop and the stress at the tower bottom; the wave and current loadings greatly affect the horizontal displacement of the foundation, and the bending moment and shearing force of the pile; and the wave loading is the most important factor affecting the pore water pressure of the seabed. The most unfavorable loading combination is the combination of the maximum wind loading and the maximum wave and current loadings with wave loading time history in this computation.