基于流–固耦合的近海风电基础地震反应分析

ANALYSIS OF SEISMIC RESPONSE OF OFFSHORE STRUCTURE OF WIND TURBINE AND FOUNDATION CONSIDERING FLUID-STRUCTURE COUPLING

结合近海风电单桩及四桩基础支撑体系工程实际场地资料,采用有限元数值分析方法,考虑水–土–结构动力相互作用,即考虑流–固耦合效应、饱和土的多孔介质渗流属性及桩–土接触相互作用,分析结构体系动力特性及地震反应。分析单桩有水与无水及四桩有水与无水4种工况支撑体系的自振特性和单桩有水与无水2种工况支撑体系的地震反应。结果表明:水层对结构低阶频率影响不大,对高阶频率降低幅度较大;水层对体系的水平位移、竖向沉降、峰值加速度及有效应力均有不同程度地削减;地震作用下土体的超静孔隙水压力呈现波动特性;结构的位移及应力响应均能满足规范要求。证明考虑多介质耦合的动力有限元分析方法是解决复杂海上风电基础地震响应的有效方法。

According to the site information of an offshore project of wind turbine, the dynamic characteristics and the seismic response of the supporting system of turbine were analyzed by considering the complicated interactions of water, soil, and supporting system. The fluid-structure coupling, the seepage of saturated soil and the pile-soil contact behaviour were simulated using the finite element method. Four working conditions were considered for the analysis of characteristics of natural vibration, i.e. the single-pile supporting with water and without water in consideration, the four-pile supporting with water and without water in consideration. The results from the simulations indicated that water had negligible influence on the lower-order frequencies of the structure, but led to a large reduction on the high-order frequencies. Water reduced the horizontal and the vertical displacements, the peak acceleration and the effective stress of the supporting system. The excess pore water pressure in the foundation soil fluctuated under seismic actions. The calculated structural displacements and effective stresses met the regulation requirements. ©, 2015, Academia Sinica. All right reserved.