可液化土－高层结构地震相互作用振动台试验

Shaking table testing on high-rise buildings considering liquefiable soil-structure interaction

摘要:

进行了可液化土－高层结构地震相互作用的振动台试验，试验采用柔性容器以减小边界影响，采用饱和砂土作为模型土。试验中再现了液化场地土中高层结构的震害现象。得出的主要规律有：相互作用体系的振型曲线与刚性地基上结构的振型曲线明显不同；随着振动次数的增加，体系的频率降低，阻尼比增大；砂土对地震动可起滤波和隔震作用；当最初加速度峰值到达前，砂土层中的孔压比存在负值；震后土中孔隙水压力不一定随振动的停止而立即开始消散，在短期内可能继续增长；桩身应变幅值呈桩顶大、桩尖小的分布；桩土接触压力幅值分布规律与输入激励地震大小有关。

Abstract:

Shaking table model test on high-rise buildings considering liquefiable soil-structure interaction is described in this paper. A flexible container was fabricated to minimize the box effect. Saturated sand soil was employed as model soil. In the test, macro-phenomena of high-rise building in ground of soil liquefaction due to natural earthquake are reproduced well. Some important findings from the present tests are as follows. The mode shape of the system is different from that of the structure on the fixed base in that there are rocking and swing at the foundation. The natural frequency of interaction system decrease and the damping ratio of soil increase with the increase of the shaking. The liquefied soil can filter and isolate vibration. The phenomena of transient minus pore pressure occurred in the test. Pore water pressure does not always dissipate in short time immediately after the excitations, but it may keep on increasing too. The distribution of the strain amplitude along the pile is the shape where the large strain is at the top of the pile and the small strain is at the tip of the pile. And the distribution of the contact pressure on the pile-soil interface is related to the excitation magnitude.