【摘要】 随着风电场场址水深和风机单机容量的逐渐增大，四桩导管架基础在海上风电中的应用越来越广泛，确保其在复杂海洋环境的服役安全性已成为我国风电行业亟待解决的关键问题之一。针对砂土中四桩导管架基础-风机结构体系，考虑风、浪、流带来的局部冲刷和循环荷载联合作用，设计开展了一系列局部冲刷条件下的长期水平风浪组合循环加载模型试验，关注不同循环荷载幅值下结构体系的累积倾角和自振频率，揭示了导管架基础顶部位移随循环加载次数的发展规律，并绘制出导管架前、后排基桩弯矩和桩身变形曲线随循环次数的演化过程。着重探讨了冲刷深度等因素对海上风机四桩导管架基础长期循环承载变形特性的影响规律，进而拟合出适用于工程设计的冲刷环境下海上风机四桩导管架基础累积位移简化预测公式。结果表明，冲刷将显著增大循环受荷四桩导管架基础的累积位移，最终变形可达冲刷前的2.8倍，且不利于整个风机结构体系的累积倾角控制；冲刷与循环荷载的长期联合作用会削弱基础-土相互作用刚度，改变其动力特性，使得风机系统的自振频率有所降低，三倍桩径冲刷深度时降幅可达10%～14%；随着循环荷载的不断施加，导管架基桩内力和变形逐渐增大，最大弯矩点有向下发展的趋势，而冲刷将加剧这一现象。更多还原

【Abstract】 With the rapid expansion of offshore wind farms into deeper waters and the concurrent increase in wind turbine capacities, the application of four-pile jacket foundations in offshore wind turbines has become increasingly widespread. Ensuring the service safety of these foundations in complex marine environments has become one of the critical problems urgently to be solved in China′s wind power sector. Focusing on the four-pile jacket foundation – wind turbine structural system in sand, considering the combined effects of local scour and cyclic loading caused by wind, waves, and currents, a series of long-term combined horizontal wind-wave cyclic loading model tests in local scour environment were designed and conducted. The cumulative inclination angle and natural frequency of the structural system were analyzed under different cyclic loading amplitudes, revealing the evolution patterns of displacement at the jacket foundation top with the increasing number of cycles. Furthermore, the evolution process of the bending moments and pile deformation curves of both front and rear piles of the jacket with the increasing number of cycles was plotted. The influence of factors such as scour depth on the bearing and deformation characteristics of offshore wind turbines with four-pile jacket foundations under long-term cyclic loading was examined, and a simplified prediction formula was developed to estimate the cumulative displacement of offshore wind turbines with four-pile jacket foundations under scour conditions for engineering design practice. The results demonstrated that the scour significantly increased the cumulative displacement of four-pile jacket foundations under cyclic loading, with final deformation reaching up to 2.8 times compared with that observed in unscoured conditions, thereby hindering effective control of the cumulative inclination angle of the entire wind turbine structural system. The long-term combined effects of scour and cyclic loading weakened the jacket foundation-soil interaction stiffness and altered the dynamic characteristics, consequently reducing the natural frequency of the wind turbine system. At a scour depth equal to three times the pile diameter, the reduction in frequency reached 10% to 14%. Additionally, ongoing cyclic loading gradually increased internal forces and deformation of the jacket piles, with the maximum bending moment point moving downward, a trend significantly intensified by scour. These findings offer critical insights into the design and safety assessment of offshore wind turbines in scour-prone environments.更多还原