水工抗震规范中高土石坝动态分布系数的探讨

Discussion on the dynamic distributing coefficient of high earth and rock-fill dam in the specifications for seismic design of hydraulic structures

我国土石坝的建设规模和难度越来越大,水工建筑物抗震设计规范的动态分布系数分布图已经不能完全满足设计要求。本文以世界同类型中最高的双江口心墙堆石坝为例,利用有限元动力分析方法,分析了坝体的加速度反应及其分布规律,并与振动台模型试验结果进行了类比。在此基础上探讨了规范的动态分布系数分布图存在的问题。研究表明,尽管试验得到的模型坝加速度反应大于原形坝计算值,但两者的加速度反应的分布规律基本一致。建议对高土石坝的动态分布系数分布进行系统的分析论证,考虑不同坝高、不同部位、不同工况和不同坝型下的加速度放大倍数,给出更为安全合理的动态分布系数图,以指导工程实践。

As the scale and complexity of earth and rock-fill dam construction become larger and larger in our country, the dynamic distribution coefficient in the specifications for seismic design of hydraulic structures could not entirely meet the requirements. This paper takes the world highest core rock-fill dam, Shuangjiangkou dam, as an example, and the acceleration amplification factor and its distribution were discussed by dynamic FEM analysis. Moreover, the calculation results were compared with the shaking table tests results. On the basis of these, the defects of the seismic design specifications were discussed. The results showed that although the calculated acceleration response of prototype was larger than that of the model dam, but the distribution laws were consistent. It is suggested that the present dynamic distribution coefficient should be improved by comprehensive study, considering dam height, position, working conditions, as well as dam type, so as to achieve more reliable and reasonable dynamic distribution coefficient for seismic design.