不同类型地震波作用下堆积体边坡动力响应及失稳特征研究

Dynamic response and failure characteristic of accumulation slope under action of different kinds of seismic load

准确理解地震作用下堆积体边坡的动力响应及失稳特征,可以为边坡抗震设计及稳定性分析方法提供依据。为了探讨不同类型地震荷载作用下堆积体边坡的失稳特征及动力响应,该文开展室内振动台模型试验。分析不同加载波形条件下边坡失稳特征以及加速度放大系数随相对高程、无量纲加速度幅值和频率参数的变化规律。探讨堆积体边坡的典型失稳特征和相关的物理机制。结果表明,正弦波作用下堆积体边坡加速度放大系数沿相对高程增长而变化较小;汶川清平波和El-Centro波作用下边坡加速度放大系数沿边坡相对高程呈较明显增大趋势。无量纲参数对放大系数影响较弱。当振动荷载达到边坡破坏的临界荷载时,边坡在短时间内即出现失稳破坏,破坏具有突发性,失稳模式具有典型的震裂-溃散型滑坡模式。在地震动力荷载作用下边坡位移变形可分为两个典型阶段:微变形阶段和急速上升大变形阶段。就该文3种波而言,在相同波峰幅值条件下,相同持续时间内正弦波所携带的总能量最大,最易使边坡失稳。

Understanding exactly failure characteristic and dynamic response of accumulation slope composed of gravelly soil under action of seismic loading can provide theory guideline for anti-earthquake design of slope.In order to investigate failure characteristic and dynamic response of accumulation slope composed of gravelly soil under action of seismic loading,the laboratory shaking table test is conducted in this paper.The variation of the amplification factor of acceleration with relative elevation,dimensionless amplitude of acceleration and frequency parameter are analyzed under different type of loading wave.The typical failure characteristic of slope and the corresponding physical mechanism are discussed.Experimental results show that the amplification factor of acceleration induced by Sine wave varies little with the increase of relative elevation,and those by El-Centro wave and Wenchuan Qingping wave have a distinctly increasing trend along the increasing relative elevation.The dimensionless parameter has a slight influence on the amplification factor of acceleration at the condition of this paper.When the vibration load is up to the critical load which will destroy the slope,the accumulation slope composed of gravelly soil will be in failure quickly.The failure of slope has abruptness and the typical failure mode of shatter-collapse.The deflection of slope can be divided into two typical phases:slight deflection phase and intensely increase and large deflection phase.For the three types of wave adopted in this paper,the whole energy carried by Sine wave is the largest at the condition of same peak of wave amplitude,which can easily lead to slope failure.