下击暴流作用下大跨越输电塔线体系非平稳风振响应研究

With the rapid development of power grid in China, an increasing number of long-span transmission tower-line systems have been constructed. On the other hand, nonstationary downbursts also occurs repeatedly. Due to the high flexibility and low damping of long-span transmission tower-line systems, the wind-induced vibration of these structures under nonstationary downbursts needs to be stuided urgently. In this project, the theoretical modeling method, wind tunnel tests and numerical analysis will mainly be utilized to investigate the wind-induced nonstationary response of long-span transmission tower-line systems under downburst winds. Starting from the wind time histories of measured downbursts, a simplfied wind field model for nonstationary downbursts will be proposed. A fast simulation method of nonstationary random processes will be developed as well. Based on the active control wind tunnel test, the aerodynamic characteristics of transmission towers under nonstatonary downbursts will be studied in order to clarify the interaction mechanism between the nonstatonary wind and transmission tower. By means of establishing the finite element model, the wind-induced response of long-span transmission tower-line systems under different cases will be calculated and analyzed. Correspondingly, some typical characteristics of response results will be found and highlighted in this study.

随着我国电网的不断发展，大跨越输电塔线体系修建得越来越多。另一方面，非平稳下击暴流也在我国时常发生。由于大跨越输电塔线体系柔度高、阻尼小，因此其在非平稳下击暴流作用下的风振响应问题亟需研究。本项目基于现场实测结果，采用理论建模、风洞试验和数值分析的手段开展下击暴流作用下大跨越输电塔线体系的非平稳风振响应研究。基于多组下击暴流实测数据，结合已有数值模拟和风洞试验结果，提出非平稳下击暴流风场的简化模型；开展非平稳随机过程模拟研究，提出一种新的高效模拟方法；基于主动控制风洞，开展非平稳下击暴流作用下输电塔的气动力特性研究，揭示非平稳风下输电塔的气动力作用机理。建立大跨越输电塔线耦合体系的有限元模型，得出多种工况下输电塔线体系的风振响应计算结果，明确大跨越输电塔线体系在非平稳下击暴流作用下的风振响应特性。

作为电网基础设施的重要组成部分，输电线塔的倒塌事故时有发生，其中很大部分是由非平稳下击暴流引起的。目前在进行输电线塔的抗风设计时通常不考虑下击暴流的作用，其原因是非平稳下击暴流风场、风荷载特性及其对输电线塔的响应影响规律等研究尚未成熟。针对上述问题，本项目开展了非平稳下击暴流风场特性及建模、非平稳下击暴流风场的高效模拟、基于主动控制风洞的非平稳下击暴流作用下矩形截面的气动力特性以及非平稳下击暴流作用下输电线塔的风振响应及易损性分析等内容的研究，取得了如下成果：1) 提出了下击暴流的自动分离算法，揭示了下击暴流风场特性，明确了非平稳下击暴流简化建模的合理性。2) 提出了一种混合多元经验模态分解和谱表示方法的单样本模拟方法以及一种混合改进插值和新矩阵分解的高效模拟方法，提高了下击暴流风场模拟的效率。3) 揭示了矩形截面迎风面、顶面和背风面各测点的时变风压、时变风压系数、风压相关系数以及时变相干函数等特性的演变规律；4) 探明了不同方向角和径向距离的下击暴流工况作用下输电线塔的风振响应特性、初始屈曲杆件位置和失效概率以及易损性曲线的变化规律。研究成果对于提高下击暴流作用下输电线塔风振响应分析的精度、效率及可靠度上具有显著的科学意义，可为输电线塔的抗下击暴流设计提供参考。