边坡地震动力响应的振动台模型试验

Shaking Table Model Test of Slope Seismic Dynamic Response

为研究坡面位置、地震动参数对加速度动力响应的影响,通过振动台模型试验,分析不同坡型的边坡动力响应,揭示了坡面形态、高程及地震波类型、振动强度、地震频率对动力响应的影响。试验结果表明:边坡模态参数与高程无关,随白噪声逐级加载,模型体系的一阶自振频率逐渐降低,阻尼比逐渐增加;凹坡测点加速度放大系数略大于凸坡相应测点,凹坡较凸坡不稳定;地震荷载下"高程放大效应"受边坡地形条件及地震动参数的影响呈现不同特征,凹坡高程放大效应较凸坡显著;坡内、坡表各测点的加速度放大系数呈折线递增趋势,但坡表各测点的加速度放大系数始终大于坡内;坡体动力放大效应与边坡自振频率密切相关,一定范围内,频率越高,放大效应就越显著;振动强度对边坡沿高程方向动力响应分布影响不大,但对边坡加速度放大效应的影响较为明显。

To study the influence of slope position and ground motion parameters on dynamic response of acceleration, through the shaking table model test, the slope dynamic responses of different slope type are analysed, the influences of slope shape, elevation, type of seismic wave, vibration intensity, earthquake frequency on dynamic response are revealed. The experimental result shows that （1） the modal parameters of slope are independent of elevation, and the first order natural frequency of the model system reduces gradually and the damping ratio increases gradually as the white noise increases gradually; （ 2 ） the acceleration amplification factor of measuring point on concave slope is slightly larger than that on convex slope, the stability of convex slope is better than concave slope; （ 3 ） under seismic load, the elevation amplification effect affected by slope topography and ground motion parameters is different, the elevation amplification effect of the concave slope is more significant than the convex slope; （ 4 ） the acceleration amplification coefficient obtained from each measure point at slope surface and inner slope shows a trend of increasing fold line, but the acceleration amplification coefficient of each measuring point of slope surface is greater than that of inner slope;（5） slope dynamic amplification effect is closely related to the natural frequency of slope, in certain range, the higher the frequency, the more significant the amplification effect; （6） along the height direction, the impact of vibration strength on the slope dynamic response distribution is little, but the impact on the slope acceleration amplification effect is obvious.