面板堆石坝震动响应及变形规律的试验研究

CENTRIFUGE MODELING TEST OF DYNAMIC RESPONSE AND DEFORMATION LAW OF CONCRETE-FACED ROCKFILL DAM

采用Parkfield波作为地震动输入,在清华大学50g-t土工离心机振动台上中进行了一组面板堆石坝动力离心模型试验。试验在50倍重力加速度条件下完成,采用加速度传感器测量了模型不同位置动力响应的加速度时程并且采用应变片测量了面板的应力-应变,通过改变地震波输入的幅值和是否蓄水分析研究了面板堆石坝的震动响应及变形规律。结果表明面板坝自下而上存在地震响应放大现象,靠近上下游坝坡位置的加速度响应要大于同高程处坝轴线附近的加速度响应;地震作用下面板产生较明显的压应力,最值发生在面板中上部;面板中部出现较明显的弯矩;改变输入地震波的幅值大小对坝体加速度响应的分布规律、坝体位移变化的分布规律以及面板应力变形的分布规律没有影响,但地震波输入幅值的增加会减弱地震波的加速度放大效应;竣工期的地震加速度响应比蓄水期的要大,说明蓄水可以削弱地震波对坝体的加速度响应,但蓄水会导致坝体和面板的变形增加。

The study on dynamic response of CFRD due to earthquake is presented using 50g-t centrifuge shaking table in Tsinghua university subjected to Parkfield earthquake.The experiment is conducted under the 50g condition. Acceleration time histories are recorded by acceleration transducer at different locations on the model and the deformation of the face-slab is also measured. The vibration response and deformation law of CFRD is studied by changing the intensity of seismic wave and water depth.The results show that the CFRD response is amplified as the seismic wave propagates upwards through the dam. The response of the zone adjacent to the upper and lower dam is greater than that of the internal dam.Significant stress and strain occur during the earthquake： compressive stress occurs on the upper part of the face slab while tensile stress occurs on its lower part; it occurs flexural torque on the middle part of the face slab. The acceleration response and the displacement distribution of the dam as well as the stress and deformation of the face slab don＇t alter by changing the magnitude of the seimic wave,but the increase of the intensity of the seimic wave will decrease the acceleration amplification of the wave.The earthquake acceleration response can be weakened by impounding which can increase the deformation of the dam and face slab.