中文摘要：

覆冰线路脱冰方式影响着整个线路的动力响应．利用数值试验方法建立了4塔5线有限元耦合模型，覆冰模拟采用附加冰单元法．研究了中跨中部导线外侧的两层覆冰同时发生脱落和两层覆冰在不同时刻相继发生不同厚度脱落时体系的动力响应．分析结果表明，两层覆冰在不同时刻相继发生脱落比覆冰在同一时刻一次性全部发生脱落引起的线路回弹高度、不平衡张力和跨中导线张力的最大值分别减小24％，17%和14％左右．当导线运动至最低点而第2层覆冰发生脱落时引起的线路回弹高度最大．无论两层覆冰脱落的时间间隔多长，线路脱冰后最终都具有相同的稳定振动状态．当最外层覆冰厚度占覆冰总厚度的3／5左右时，分层脱冰对线路体系的影响最小．对覆冰分层脱落的研究结果表明，以往采用覆冰一次性全部脱落假设得到的线路脱冰荷载取值偏保守，尚有可供优化的空间．

英文摘要：

The ice-shedding way of iced conductors affects the dynamic response of transmission line system.In this paper,a finite element model of 4 towers and 5 spans is established by numerical method, and the ice is simulated by additional ice element method.The dynamic responses of the structure are ana- lyzed when two-layer ice at mid-span of the middle conductor peels off at the same time and at different time with different thicknesses. The results show that the maximum rebound height, unbalanced tension and wire tension induced by one time ice-shedding are 24~, 17~ and 14~ lower than those by ice- shedding at different time, respectively. The maximum rebound height of the system occurs when the second layer ice peels off and the conductor moves to the lowest position at the same time.The structure exhibits the same stable vibration state regardless of the interval time of the two ice layers shedding.When the thickness of outermost layer accounts for 3/5, the effect of ice layers shedding is minimal.The conclusions obtained by ice layer shedding research show that the values of ice-shedding load based on the as sumption of one time ice-shedding are conservative,and there is some space for optimization.