水平黏性土地基动力离心模型试验

DYNAMIC CENTRIFUGAL MODEL TEST ON HORIZONTAL CLAYEY GROUND

从黏性土地基模型的制备、固结到50 g离心机加速度条件下对振动台激励的反应等方面,介绍水平黏性土地基地震动力响应的离心模型试验方法和步骤。试验结果表明,在地震动作用下,所研究的黏性土地基土层从下到上最大地震峰值加速度逐渐增加,说明该自由场地基土层从下到上对地震有放大作用。从土层的加速度反应谱可以看出,在输入的Parkfield地震波作用下,该地基的自然频率为0.5 Hz,地基对低频成分有放大作用,而对大于10 Hz的频率成分几乎没有放大作用。由位移和孔压的变化曲线可知,地基表层土在地震过程中发生的侧向位移最大,而表层以下的土层侧向位移不大。地震过程中中下部土层的孔压增长量最大,中上部土层的孔压增长量次之,底部土层的孔压增长量最小。

The study on dynamic response of clayey ground due to earthquake is presented using centrifugal shaking table.The details of the experiment are described including the preparation of model,consolidation of the clayey ground and dynamic centrifugal model at condition of 50 g centrifugal acceleration.The model test results indicate that the peak amplitude of the response acceleration increases from bottom to surface.From the results of the spectral amplification of acceleration,it can be seen that the range of low frequency below 10 Hz is amplified;and the resonance frequency of the concerned clayey ground is about 0.5 Hz with the action of input Parkfield Seismic wave.The lateral displacement of the surface layer is maximum;and the middle and bottom layers are not evident.The curves of pore pressure change show that the pore pressure increase of the middle stratum is maximum and the substratum is minimum.