考虑库水可压缩性的重力坝地震动力响应分析

Analysis of Seismic Response and Dynamic Characteristics of Gravity Dam Considering Water Compressibility

为研究库水压缩性对坝体动力特性的影响,以某重力坝为例,建立4种不同库水作用有限元模型。对比传统的附加质量模型、折半修减的附加质量模型和忽略库水压缩性模型得到的坝体自振频率、坝体关键部位峰值应力与位移及坝面的动水压力分布,表明:附加质量模型在一定程度上夸大了水体的作用,导致坝体的基频降幅最大,增大了坝踵部位的峰值应力,对坝体中上部的动水压力有明显的放大现象,但对坝顶位移有一定的削弱;可压缩库水模型可以更好地反映库水与坝体之间的相互作用,因此在计算中不应忽略库水的可压缩性影响。

In order to explore the influence of water compressibility on the dynamic response of dam,taking a gravity dam for an example,four different finite element models for the reservoir water were established by using ANSYS. The natural vibration characteristics,peak stress and the displacement of major position,and the distribution regularity of dynamic water pressure were got by comparing the four models. The results demonstrate that added-mass model overestimates the influence of water,leads to the natural frequency of dam larger decline,increases the peak stress of dam heel,but the displacement of dam crest have weakened; compressible reservoir model can better reflect the interaction between water and dam,therefore the water compressibility should not be ignored.