覆冰导线舞动作用下输电塔破坏机理的试验研究

Test for failure mechanism of a transmission tower under iced conductor galloping

以某转角耐张塔为研究对象,基于模型相似理论,设计制作了覆冰导线模型和弹性边界条件下的大比例输电塔节段模型,并根据覆冰导线舞动特征,研制了用于模拟导线舞动的动力加载装置。同时,结合实际线路舞动时的特征参数,于试验室条件下进行了覆冰塔线体系舞动事故的反演,并根据试验测得的构件动应力幅值,计算了输电塔构件在导线舞动作用下的疲劳寿命。研究结果表明:该输电塔在导线舞动作用下的失效并非由构件承载力不足和疲劳损伤而造成的,其原因在于构件连接螺栓在导线舞动产生的大幅动张力作用下发生松动,使部分构件的内力重分配,导致某些杆件受力过大而发生破坏,从而引发了输电塔的失稳甚至倒塌。

Based on the similarity theory of dynamic models, a large scale tower segmental model with elastic boundary condition and iced conductor model was built. According to dynamic characteristics of iced conductor galloping, the vibration test equipment used to simulate galloping responses of iced-conductor was developed. On the basis of conductor ice thickness and vibration amplitude obtained with field testing, a dynamic test of a transmission tower-line was performed under conductor galloping. Combining with the test results of dynamic stress, the fatigue life of tower members was estimated. It was shown that failure mechanism of a tower is not insufficient bearing capacity of members and fatigue damage, but the looseness of the connection bolts of members under dynamic tension produced by conductor galloping ; the looseness causes the internal force redistribution for the main components of tower, thus some members are destroyed due to the action of excessive force, the destroyed members lead to instability and collapse of a transmission tower.