可液化土层对土-地下结构地震反应的振动台试验设计

Experimental Design of Shaking Table Test on Seismic Response of Soil and Underground Structures in Liquefiable Soil

液化区域与结构的相对位置和液化场地产生的大位移,对地下结构的动力响应存在很大的影响。基于此,采用振动台试验,针对目前地铁区间隧道建设中常见的单层双跨断面形式结构,开展了一系列振动台试验。系统阐述了本次大型振动台试验中方案设计相关内容,包括相似关系设计、地基土制备、结构模型制备、防水处理、试验测试技术与传感器布置、试验工况设置等,并对液化场地自由场工况的地基土地震反应进行分析。结果表明:本次系列试验设计方案可以形成较好的液化宏观试验现象;模型箱的边界效应较小;相同地震动峰值条件下Kobe波和北京人工波作用时,土体产生的剪切变形最大,名山波作用下土体产生的剪切变形最小。试验设计思路和前期试验结果可以为振动台后期试验的顺利展开做好准备工作。

The relative position between the liquefaction area and the structure,and the large displacement induced by the liquefaction site have a great influence on the dynamic response of the underground structure.Based on this,the research group carried out a series of shaking table tests on the single-layer double-cross-section structure commonly used in subway tunnel construction.This paper systematically expounds the relevant contents of the scheme design in this large-scale shaking table test,including similarity relation design,foundation soil preparation,structural model preparation,waterproof treatment,test technology and sensor arrangement,test condition setting and so on.The seismic response of foundation soil in free field condition of the liquefaction site is analyzed.The main contents and achievements are as follows:the series of test design schemes can produce a better macroscopic liquefaction test phenomenon;the boundary effect of the model box is small;under the same peak value of ground motion,Kobe wave and Beijing artificial wave lead to the largest shear deformation of soil,while Mingshan wave produces the smallest shear deformation.The idea of test design and the previous test results can make a good preparation for the later shaking table test.