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水平场地地震响应分析是岩土地震工程实践中最重要的问题之一.深圳近年多次经历外围地震引起的小振动,因而研究场地在小震作用下的响应有特殊意义.利用香港科技大学离心机及双向振动台,进行饱和砂土场地的动力模型试验.观测模型在原型峰值加速度为0.07g的小震作用下,加速度、侧向位移、竖向沉降及超静孔压等方面的响应.发现在地震过程中,土体变形较小,超静孔压比也小于0.5,但超静孔压的变化使场地固有频率靠近输入地震波的频率,加速度的放大系数最大可达到3.67.分析结果表明,小震作用下场地虽不大可能发生液化,但在特定情况下,仍可能对上部结构造成破坏.
The analysis of horizontal site seismic response is one of the most important problems in the practice of geotechnical seismic engineering.Shenzhen experienced many minor vibration induced by peripheral earthquakes in recent years, so the response of study site under the action of minor earthquakes is of special significance.Using centrifugal of Hong Kong University of Science and Technology Machine and two-way shaking table, the dynamic model test of the saturated sand site was conducted.The response of the observation model to the acceleration, lateral displacement, vertical settlement and excess pore pressure under the action of a small earthquake with a peak acceleration of 0.07g. It is found that soil deformation is small and the excess pore pressure ratio is less than 0.5 during the earthquake, but the variation of the excess pore pressure causes the natural frequency of the site to approach the frequency of the input seismic wave, and the maximum amplification coefficient of acceleration can reach 3.67. Although the site is unlikely to liquefy under the action of a small earthquake, it may still cause damage to the superstructure under certain circumstances.