冲击荷载作用下混凝土重力坝破坏特性分析

Damage Characteristics of Concrete Gravity Dam under Impact Load

冲击荷载作用下混凝土重力坝破坏特性较静荷载作用下要复杂得多。采用钢板均匀冲击模拟水下循环冲击波对混凝土重力坝的作用,试验遵循几何和重力相似准则,对模型重力坝进行均匀冲击破坏特性研究,得到模型坝体的动力破坏特性,并对裂缝位置和扩展情况进行定位和追踪。试验结果表明:当坝体遭受循环均匀冲击荷载时,上游坝面坝体最大动应变不再在坝踵处,而是位于坝体中部;坝头部位是抗冲击的薄弱部位,最先出现开裂破坏;坝体破坏模式包括贯穿性断裂、碎裂、层裂和抛掷等。试验结果可为大坝的运行管理、防爆抗振设防及安全评价提供理论依据和技术支持。

The dynamic responses of concrete gravity dam under impact loading are much more complicated than that under static loading. In this paper the damage characteristics of gravity dam is researched by applying steel uni- form impact to simulate the cyclic impact of wave loading underwater on concrete gravity dam. Geometrical and gravity similitude are both satisfied in the model test. The dynamic responses of model dam are obtained, and the position and propagation of cracks are observed and tracked. Results reveal that when the dam is subjected to cyclic uniform impact loading, the maximum strain of dam is at the middle of the upstream dam face rather than at the dam heel; cracking damage occurs first at the jetty head which is a weak part of impact resistance. The failure modes of concrete gravity dam under cyclic uniform impact include cracking, fragmenting, spalling and throwing. The results provide theoretical basis for the operational management, shock resistance and safety evaluation of dams.