大型复杂结构-桩-土振动台模型试验土箱设计

Soil Chamber Design of Shaking Test Table for Large-Scale Soil-Pile-Complex Structure Interaction

以基于天津站交通枢纽的大型复杂结构-桩-土振动台试验为背景,详细介绍土箱设计特别是其边界设计,通过试验数据并结合模型模态分析对边界效应进行定量分析,检验土箱边界实际效果并为边界的进一步改进提供事实依据.研究结果表明:在土箱底部,通过设置分割条嵌入模型土中做成的摩擦边界的效果较好;在土箱垂直于地震动两侧壁上,聚苯乙烯泡沫塑料做成的柔性边界对Taft波和人工波加载的效果比较好,而对天津波加载效果略差;在土箱平行于地震动两侧壁上,通过侧壁内表面贴聚氯乙烯薄膜并涂抹润滑油做成的滑动边界起到一定的效果,但偏差较大.对模型土的模态分析表明:通过提高模型土域的宽高比以及适当减小柔性边界的弹性模量都可以明显减小柔性边界对模型土的影响.土箱设计总体效果较为理想,边界设计及分析可为类似土-结构相互作用振动台试验提供借鉴.

A soil chamber design was discussed in detail, especially its boundary configurations for the shaking table test of the large-scale complex structure-pile-soil interaction of the transportation junction in Tianjin Railway Station. The practical effectiveness of the soil chamber＇s boundary was tested quantitatively through data analysis and modal analysis, which could also provide factual basis for optimizing the soil chamber＇s boundary configurations. The study shows that the frictional boundary with dividing strip embedded into the model soil at the bottom of the soil chamber works very well. It is also proven that the flexible boundary made of foamed polystyrene on the side walls perpendicular to the seismic direction works well to Taft seismic wave and artificial seismic wave but it doesn＇t work so well to Tianjin seismic wave. The sliding boundary using oil lubricated polyvinyl chloride film attached onto the longitudinal inner side surface of the soil chamber works with relatively large deviation. The modal analyses indicate that increasing both the width height ratio of the soil domain and the elastic modulus of flexible boundary can reduce the effects of the flexible boundary on the model soil. It can be concluded that the overall boundary design of the soil chamber is perfectly acceptable, and it provides a good reference to similar shaking table test of soil-structure interaction.