地震作用下堆积体边坡的坡面变形与失稳机制

地震作用下堆积体边坡的动力响应特性十分复杂，单一抗震安全系数不足以评价其动力稳定性。通过大型振动台试验，研究了连续多级地震荷载作用下，地震波的类型、卓越频率及峰值加速度对堆积体边坡坡面永久位移的影响，并初步分析其失稳机制。试验结果表明，相同峰值加速度下振动型地震波比冲击型地震波更容易产生坡面永久位移，地震波卓越频率对坡面永久位移也有重要影响；堆积体边坡在峰值加速度apeak=0.2g时开始有大颗粒石砾滚落，对应的坡面永久位移在apeak=0.2g～0.3g之间开始产生并显著增大，另外利用考虑坡面几何形态变化的改进Newmark法对坡顶的永久位移进行了估算。通过坡面永久位移评价堆积体边坡的动力稳定性有一定合理性。

Surface deformations and failure mechanisms of deposit slope under seismic excitation

Dynamic response of a deposit slope under seismic excitations are very complex, and it is insufficient to evaluate the seismic stability of slope just by using the single seismic safety factor. Through the large-scale shaking table tests, the influences of the input seismic wave are investigated on the permanent displacements of slope surface under multiple sequential ground motions, and the failure mechanisms of deposit slope are analysed. The experimental results show that the vibration type of seismic wave can result in more permanent displacement than the impact type of one at the same peak acceleration. It is also found that the predominant frequency of seismic wave has significant effect on permanent displacement. When the peak acceleration of seismic wave reaches 0.2g, the large gravel particles on the deposit slope surface begin to roll. The corresponding permanent displacement of slope surface begins to accrue, and it increases significantly when the peak acceleration increases from 0.2g to 0.3g. An improved Newmark approach is used to estimate the permanent displacement of the crest, with assuming that the formulation of the yield acceleration is geomertric-dependent. It is shown that the permanent displacements of slope surface can be used to evaluate the deposit slope dynamic stability.