中文摘要：

寒区河流在春季往往会由于水力因素的剧烈变化而引发冰盖溃决,国内俗称为＂武开河＂。这一现象会导致冰坝形成,进而形成凌洪灾害。基于弹塑性力学分析,得到了考虑塑性变形的开河极限应力计算公式,与仅考虑弹性变形的极限应力公式相比,前者计算结果约为后者的1.39倍。通过黄河河曲段实例应用分析表明,开河前夕,将冰盖视为弹塑性材料,比视为完全弹性材料能够更好地消除判别结果误差,可为武开河判别提供理论参考。

英文摘要：

Mechanical ice-cover breakups often happen when the hydrodynamic conditions change rapidly in cold region rivers during the spring season , which is commonly known as ＂ Wu Kai He ＂ in Chinese. The breakup of ice-cover would result in the formation of ice dam and even the flood disasters. Based on the elastic-plastic theory , the formula for calculating the limit stress has been established. Analytical re sults show that the limit stress calculated by assuming ice-cover as the elastic-plastic body is approximate ly 1.39 times than the computing result if taking ice-cover as an absolute elastic body. By using the obser vation data of Hequ Section at the Yellow River , the results error was effectively eliminated when assuming ice-cover as the elastic-plastic body , which provides a mechanical criterion based on the theory evidence.