高面板堆石坝面板地震动力反应特性大型振动台模型试验研究

摘要

The concrete face slab is the key structure in the anti-seepage system of the concrete faced rock fill dam,and its safety is the basic guarantee for normal running of the dam.Structural safety of the face slab may be affected greatly by the superposition of dynamic response and static response in the strong earthquake,and the dynamic response characteristics of the face slab has always been the focus in the areas of dam anti-seismic research.In this paper,large-scale shaking table model tests of the high concrete faced rock-fill dam are carried out to study the dynamic response characteristics of the face slab.The dynamic strain response process of the dam face slab and the spatial distribution law of peak values of strains are analyzed firstly.Then,the dynamic stress response process of the dam face slab and the spatial distribution law of peak values of stresses are studied based on the dynamic strain response process and the material mechanics theory.Finally,the dynamic response characteristics of the prototype dam's concrete face slab are investigated based on the results of shaking model tests and the similarity law.The results show that the measured dynamic strain response process of the dam face slab in the shaking model tests and the corresponding calculated dynamic principal stress & strain response process are coincident with the general recognition to the dynamic response characteristics of the dam face slab,and the dam shaking model test can be used as an important method to research dynamic response characteristics of the dam face slab.The peak values of the principal strain appear on the altitude of about 0.6 dam height on dam vertical direction,and the peak values of the principal stress also appear on the same height correspondingly.The dynamic tensile stress undertaken by the concrete face slab in earthquake is less than the dynamic compressive stress generally.%混凝土面板是面板堆石坝整个防渗体系的核心结构,其结构安全性是整个大坝系统正常运行的基本保障.强震作用下,面板产生动应力应变反应与静力作用效应相叠加,可能会对面板的结构安全性产生重大影响,故面板的地震动力反应特性一直都是大坝抗震设计关注的重点问题.通过高面板堆石坝大型地震模拟振动台模型试验,研究面板在地震作用下的各向动应变反应过程及其极值空间分布规律,再根据面板动应变反应过程和材料力学理论分析面板的动应力反应过程及其极值空间分布特性,并利用振动台模型试验成果推求研究原型坝混凝土面板的动力反应特性.研究表明:振动台模型试验实测面板三向应变反应过程及其推求的主应变、主应力过程符合对面板动力反应特性的一般认识,振动台模型试验可作为研究面板动力反应特性的重要手段;沿竖直方向上,面板的大、小主应变极值均出现在0.6倍坝高左右的高程上;和应变分布规律基本对应,面板的大、小主应力和最大剪应力极值同样分布在0.6倍坝高左右的高程上;面板在地震中所受动拉应力水平总体低于动压应力.