近水面、库中、库底水下爆炸荷载作用下混凝土重力坝的破坏模式对比

Comparison of failure modes of concrete gravity dams induced by underwater explosion loads near the water free surface,the middle,and the bottom of the reservoir

遭受攻击时,随着弹药起爆深度的不同,大坝可能经历近水面、库中和库底水下爆炸。为明确其中最危险的工况,建立炸药-库水-空气-坝体结构的全耦合数值模型,对混凝土重力坝水下爆炸问题开展全过程数值模拟研究。该数值模型基于前期开展的离心模型试验建立,并经由两组不同工况离心模型试验的结果验证。随后,利用该模型对比分析不同爆深水下爆炸对混凝土重力坝的毁伤效应。结果表明:水下爆炸荷载下,大坝呈现三种主要破坏模式:(i)大坝上部一定深度溃口的结构破坏;(ii)大坝沿着坝底整体滑动的失稳破坏;(iii)大坝以坝趾为基点整体倾覆的失稳破坏。近水面水下爆炸时,大坝主要呈现破坏模式(i);库中水下爆炸时,大坝主要呈现破坏模式(i)和(ii)或(i)和(iii);库底水下爆炸时,大坝主要呈现破坏模式(ii)。随着爆深增加,水下爆炸对混凝土重力坝的毁伤效应先增加后减小,即库中水下爆炸是最危险的工况。文章得到的大坝破坏模式与已有文献中的试验结果和历史战争中典型大坝的破坏模式相近。

Under attack,dams may undergo underwater explosions near the water free surface,the middle,and the bottom of the reservoir depending on the detonation depth of the bomb.To determine the most dangerous situation,a fully coupled explosive-water-air-dam numerical model was established and the whole process of a concrete gravity dam subjected to an underwater explosion was simulated.The numerical model was established based on centrifuge tests previously performed and was validated by experimental data from two centrifuge tests.Furthermore,with this numerical model,a comparative study of dam failures caused by underwater explosions with different detonation depths was conducted.Results demonstrate that dams against underwater explosions exhibit mainly three failure modes:(i)structural failure with a breach of certain depth in the upper part of dam;(ii)instability failure with overall sliding of the dam in its bottom;(iii)instability failure with a whole overturning of the dam with the dam toe as the base point.For underwater explosions near the water free surface of the reservoir,dams mainly exhibit the failure mode(i);for underwater explosions near the middle of the reservoir,dams mainly exhibit failure modes(i)and(ii)or(i)and(iii);for underwater explosions near the bottom of the reservoir,dams mainly exhibit failure mode(ii).As the detonation depth increases,the damage effect of underwater explosions on concrete gravity dams may increase firstly and then decrease,that is to say,the underwater explosion near the middle of the reservoir is the most dangeroussituation.The dam failure modes obtained here are similar to the experimental results in the existing literature and the failure modes of typical dams in historical wars.