覆冰舞动下500 kV猫头铁塔损伤分析及改造技术

500kV猫头塔在我国超高压输电网系统中发挥着重要的作用,但其在覆冰舞动条件下的倒塌事故频繁发生。针对覆冰舞动条件下输电铁塔杆件内力的准确计算问题,本文首先引入超静定结构的概念,提出了一种基于n次超静定结构的杆塔内力求解方法；然后根据导地线参数推导出了覆冰舞动条件下挂线点的受力情况；最后基于铁塔桁架结构和载荷分布的对称性,将全塔模型简化为1/4模型进行内力计算,并对螺栓组的连接强度进行校验。以500kV宜兴Ⅰ回线路141#为例,对新方法的计算准确性进行验证。结果表明：内力计算值与仿真值之间的偏差均小于10%；采用新方法能够实现薄弱点的准确定位,并对薄弱点周围的螺栓组采取补强措施。该研究对今后的舞动区铁塔设计和改造具有一定的指导意义。

Damage analysis and reconstruction technology of 500kV cat head tower under ice dancing

The 500kV cat head tower plays an important role in EHV transmission network system. However, its collapse accident under ice-dancing condition frequently occurs. In order to accurately calculate the internal force of tower under ice-dancing condition, firstly, the concept of statically indeterminate structure is introduced, and a method for determining the internal force of tower is proposed based on the n-time statically indeterminate structure. Then, the forces of the hanging point under ice-dancing condition are derived according to the parameters of the line. Finally, based on the symmetry of the tower truss structure and load distribution, the whole tower model is simplified to a quarter model for the internal force calculation, and the joint strength of the bolt group is verified. Taking the 500kV Yixing I line 141# as an example, the calculation accuracy of the new method is verified. The results show that the deviation between the calculated value and the simulated value of the internal force is less than 5%. The weak points can be accurately determined by using the new method, and the bolt groups around the weak point are reinforced. This work has certain guiding significance for the future design and reconstruction of the tower in the ice-dancing region.