山区输电塔线体系覆冰断线效应研究

Research on Icing Wire-breaking Effects of Transmission Tower-line Systems in Mountain Areas

采用索单元和梁单元模拟输电导线和结构杆件,基于非线性有限元理论建立了塔线体系在覆冰荷载作用下的断线效应的评价方法。以南方某重覆冰山区的实际两塔三线输电线路为工程背景,研究了不同覆冰断线工况下塔线体系动力响应的特点。结果表明:山区输电线路的覆冰断线效应显著。塔底部分主材杆件已经超过了其强度极限并已进入塑性阶段。而塔顶地线位置的部分杆件应力虽然没有进入塑性,但强度储备已经较小。因此,在山区应充分考虑覆冰的灾变效应,即便不是严重覆冰也有可能引起严重的灾变事故。

The analytical model of a transmission tower-line system with multi towers and lines was developed by simulating transmission lines and members based on the spatial cable elements and beam elements. The dynamic analytical method of icing wire-breaking effects of transmission tower-line system was established based on nonlinear finite element method. A real transmission tower-line system with two towers and three lines in the southern icing mountain areas was taken as an example to investigate the properties of the dynamic responses induced by icing wire-breaking accidents. The made observations indicate that there exist obvious dynamic effects after icing wire-breaking accidents in mountain areas. The axial stresses of some major members at the bottom of the tower are quite large and the members are in the stage of plasticity. The axial stresses of some members adjacent to the earth wires are under ultimate strength while the strength storage is quite limited. Therefore, it is essential to take the effects of icing loads into consideration because even a medium level of icing loads may induce severe dynamic disasters of transmission tower-line system.