考虑强震能量持时的混凝土重力坝损伤累积效应研究

Research on damage accumulation effect of a concrete gravity dam considering the energy duration of strong earthquakes

地震动持时对大坝的损伤演化有显著影响,但目前在多向地震动持时方面的研究较少。为综合考虑多向地震动持时对重力坝累积损伤的影响,以某重力坝为研究对象,考虑混凝土的塑性损伤模型,分别考虑单一水平向、水平向和竖向两向地震动作用,采用综合能量持时公式研究综合能量持时对大坝损伤累积效应的影响,以及不同强度阈值范围的能量持时与大坝损伤指标之间的相关性。研究表明:能量持时对大坝的损伤破坏有显著影响,长持时的地震动会对大坝造成更严重的损伤破坏;竖向地震动作用会加剧大坝损伤破坏,进行大坝动力计算时应考虑地震动竖向分量的影响;15%~85%强度阈值范围的能量持时与损伤指标之间的相关性最优。研究成果可为大坝抗震设计提供参考。

The duration of ground motion induced by earthquakes has a significant impact on the damage evolution of dams,but there are few studies on the duration of multi-directional ground motions. In order to comprehensively investigate the impact of multi-directional ground motion duration on the cumulative damage of gravity dams,a gravity dam was taken as the research object to establish a finite element model with the consideration of plastic damage model of the concrete and the unidirectional horizontal and twodirectional seismic effects. Then the integrated energy duration formula was used to study the impact of integrated energy duration on the damage accumulation effect of the dam,and the correlation between energy duration in different threshold ranges and dam damage indicators were discussed. The results show that energy duration has a significant impact on the damage failure of dams. Long-term ground motions will cause more severe damage to the dam. Vertical ground motions have a certain impact on the damage failure of the dam,which should be considered in the dynamic calculation. The energy duration in the intensity threshold range of 15%-85% has the best correlation with the damage indicators. The research results can provide some reference for the seismic design of dams.