强地震作用下混凝土重力坝响应特性分析

Analysis on response characteristics of gravity dam under strong earthquake effect

研究了混凝土重力坝在高强度地震作用下的响应特性,分析了在地震峰值加速度不断增加时坝体屈服区域的发展方向。针对两个典型坝段,运用混凝土塑性损伤模型模拟了其结构的非线性特性。考虑了地震情况下动水压力的作用,通过动力有限元时程分析法计算了不同地震条件下两个坝段的动态响应。计算结果表明:当地震加速度较小时,重力坝只在坝踵区域出现小部分屈服,坝体能正常工作。若提高地震烈度,则局部损伤会纵深发展到达灌浆廊道部位,坝体会形成贯穿上下游的屈服区域并逐渐扩大致使结构失去稳定性。经两个坝段计算结果相互比较,得到了混凝土重力坝在强震作用下的非线性破坏形式,较为真实地反映出坝体的响应。

The response characteristics of concrete gravity dam under high intensity earthquake is studied herein, and then the developing direction of the yielding area in the dam body during the continuous increase of the peak seismic acceleration is ana- lyzed as well. For two typical dam sections, the nonlinear characteristics of the structures are simulated with the concrete plastic damage model. Under the consideration of the effect of the dynamic water pressure under earthquake, the dynamic responses of both the dam sections under different seismic conditions are calculated with the dynamic finite element time-history analysis meth- od. The calculation result shows that when the seismic acceleration is smaller, only a small fraction of yield occurs at the heel ar- ea of the gravity dam, thus the dam can normally operated. If the seismic intensity is increased, the local damage is to be devel- oped to the grouting gallery, and then an upstream to downstream yielding area is to be formed and continuously enlarged, thus makes the structure lose its stability. Through the comparison made between the calculation results of both the dam sections, the nonlinear failure pattern of concrete gravity dam under strong seimie effect is obtained, which more truly reflects the response of the dam body. The study has a certain reference significance for the seimie study on gravity dam.