考虑土-结构相互作用的大型风电结构地震响应分析

Seismic response analysis of large wind turbine considering soil-structure interaction

为研究地震易发区土-结构相互作用(SSI效应)对大型风电结构地震响应的影响程度,该文以某2.5MW大型风电结构为对象,首先建立其“叶片-机舱-塔架-基础-土体”耦合的精细化整体有限元模型,并基于场地土特性设置土体参数。其次,利用PEER数据库选取四种不同类型地震动,在考虑土体非线性特征的基础上,通过EERA程序得到实际土层底部的地震动加速度时程序列。最后,以风电结构塔顶位移、塔身应力、加速度及塔底内力响应为地震响应的分析指标。结果表明:远场地震动作用下大型风电结构动力响应较近场地震动作用下更大;考虑SSI效应会降低风电结构的自振频率,使塔顶相对位移时程出现不平稳现象,并更易激发结构高阶振型;在高频成分显著的近场非脉冲型地震动作用下,考虑SSI效应前后风电结构塔身最大应力以及塔底最大剪力与弯矩差异较大。在以后大型风电结构的设计中应更加细致地考虑SSI效应的影响,尤其是在高频地震作用下。

This paper studies the influence of soil-structure interaction(SSI effect)on the seismic response of large wind turbine in earthquake prone areas.In this paper,a 2.5 MW wind turbine is taken as the object,and the fine global finite element model of“blades-nacelle-tower-foundation-soil”coupling is established,and the soil parameters are set up based on the characteristics of the site soil.Secondly,four different types of ground motions are selected by using PEER database.On the basis of considering the nonlinear characteristics of soil,the acceleration time history sequence of ground motion at the bottom of soil layer is obtained by EERA program.Finally,the displacement of tower top,the stress and acceleration of tower body and the internal force response of tower bottom are taken as the analysis indexes of seismic response.The results show that the dynamic response of large wind turbine under far-field ground motion is larger than that under near-field ground motion,and considering SSI effect will reduce the natural vibration frequency of wind turbine,make the relative displacement time history of tower top unstable,and it is easier to excite the high order vibration mode of the structure.Under the action of near-field non-pulse ground motion with significant high frequency composition,the maximum stress of wind turbine tower before and after SSI effect and the maximum shear force and bending moment at the bottom of the tower are quite different.The influence of SSI effect should be considered more carefully in the design of large wind turbines in the future,especially under the action of high-frequency ground motions.