大跨越输电塔线体系覆冰脱落致连续倒塌机理研究

The longitudinal unbalanced tension of transmission lines caused by ice-shedding is one of the main causes of progressive collapse of transmission towers in ice disasters. To obtain the progressive collapse process accurately, the accurate finite element model of tower-line system should be established. First, the hysteretic load-displacement curves of bolt slip and the hysteretic bending moment-rotation angle curves for typical joints of the transmission tower are derived. In addition, the cyclic loading tests of typical joints are performed, then the theoretical model is modified according to the test results. After that, the simulation method of joint effects in finite element software is proposed. Then the finite model of transmission tower system is established by introducing the initial bending defects, installation defects and joint effects. Considering the possibility of ice-shedding during the vibration, the dynamic response and the progressive collapse process of transmission lines caused by ice shedding are investigated, and the dynamic characteristics and the mechanism of the progressive collapse of transmission lines caused by ice shedding are revealed. This study has a very improtant significance to improve the operating safety, enhance the capability of resisting ice disaster and formulate relevant guidelines for tranmission line.

覆冰脱落引起的输电线路纵向不平衡张力是冰灾中输电塔连续倒塌的主要原因之一。为了准确地获得覆冰脱落导致的输电塔线体系连续倒塌过程，需要建立精确的塔线体系力学仿真模型。本项目首先推导输电塔典型节点的螺栓滑移荷载-位移滞回曲线以及弯矩-转角滞回曲线；并根据输电塔典型节点循环加载试验结果，对理论模型进行修正。此后，提出节点作用在有限元软件中的模拟方法，引入杆件初弯曲、安装缺陷和节点作用，建立较为完善的输电塔线体系力学仿真模型，考虑振动过程中残余覆冰脱落，对输电线路动力响应及其连续倒塌过程开展研究，揭示塔线体系的振动特性以及连续倒塌机理。本项目的完成对于提高输电线路的安全性，增强输电线路抵御冰灾的能力以及制定相关设计规程具有重要的工程实际意义。

覆冰脱落引起的输电线路纵向不平衡张力，是冰灾中输电线路发生连续倒塌的主要原因之一。本项目对输电塔的精确建模和覆冰脱落致输电线路连续倒塌机理开展了系统研究。选取输电塔的典型节点作为研究对象，通过数值模拟和模型试验获得了搭接节点的荷载-位移滞回曲线和K节点的弯矩-转角滞回曲线。结合理论分析，研究了这两种节点在往复荷载作用下的力学特性。提出了节点作用的仿真方法，并将其引入输电塔仿真建模中。提出了一致模态法来考虑输电塔的初始缺陷，并通过全尺寸试验进行了验证。在此基础上，建立了输电塔的精确数值仿真模型。在研究现有脱冰方法的基础上，提出了一种结合短路电流与冲击荷载的覆冰线路脱冰方法。对输电塔-线体系由覆冰脱落引起的振动进行了系统研究，分析了节点作用和线路参数对塔-线体系振动的影响。对覆冰脱落引起的塔-线体系连续倒塌全过程进行了分析，提出了一种减小输电线路纵向不平衡张力的装置，可用于防止输电线路连续倒塌，并通过数值方法验证了其有效性。此外，本项目还通过风洞试验研究了两种典型覆冰导线的气动力特性，并对其影响参数进行了分析。本项目的研究成果可用于指导大型输电设施建设和有关设计规范的制定。