本文通过进行不同地震动输入的振动台模型试验,研究模型坝的动力特性及其变化规律,并通过土石坝振动台模型试验相似率推算了原型坝的动力特性。研究表明:(1)对于一次振动,模型坝各测点所得自振频率及阻尼比基本一致,表明坝体具有大致固定的振型;(2)随台面激励峰值加速度的增大,自振频率明显降低,而阻尼比增大;(3)自振频率及阻尼比均与先期振动历史密切相关,先期振动使坝体自振频率减少,阻尼比增大,先期振动的影响与先期振动的强度有关;(4)蓄水对模型坝的自振频率有明显影响,坝体自振频率在满库时明显比空库时低。
Dynamic behaviors are studied by the shaking large-scale table tests of a whole model and a section model in gravity field,and the dynamic responses of the prototype earth-rockfill dam are predicted according to the similitude.This study shows that:(1) The natural frequency and damping ratio at different sampling points are nearly uniform under the vibration of fixed peak acceleration.This indicates a relatively stable vibration mode of the model dam;(2) The natural frequency is considerably lowered with the increase of seismic peak ground acceleration;(3) The natural frequency and damping ratio are closely related to pre-vibrations.Pre-vibration causes a lower natural frequency and a greater ratio,and its effect depends on its intensity;(4) Reservoir filling has a considerable impact on the natural frequency,and the frequency of a full reservoir is lower than an empty reservoir.