地下结构地震反应的振动台模型试验研究

Analysis of Shaking Table Test on Underground Structure

摘要:

进行了土地下结构动力相互作用的大型振动台模型试验，分别测出了模型土中不同部位的加速度反应和地下结构的加速度与应变反应.对模型体系的加速度反应实测值进行整理分析了模型箱效应、试验各阶段系统的自振频率及阻尼比的变化情况和地下结构的加速度和应变反应规律.试验结果表明：相对于仅有水平加速度激振，峰值约为水平加速度峰值三分之二的竖向激振的参与，可使结构的反应增加，且应变反应的增量大于加速度反应的增量，地下结构横断面的变形仍以剪切变形为主；地下结构的加速度反应和应变反应的频谱分布有较大差异，应变反应中竖向振型的贡献较大.

Abstract:

During the shaking table test, the acceleration responses of the soil mass and underground structure model, the strain responses of underground structure model were obtained. The simulative effect of boundary was evaluated by analyzing the seismic response acquired from accelerometers. At the same time, the change in natural frequencies and relative damping ratios of soil were also expatiated. And then the rules of the earthquake responses of structure model were concluded on the basis of the test result. The test results show that, compared with the only horizontal acceleration excitation, vertical acceleration excitation’s participation, whose peak was about 2/3 of the peak of the horizontal acceleration excitation, can increase the responses of the structure, and the increment of strain responses are larger than the acceleration responses. Shear deformation is a major deformation pattern for the structure model cross sections.There was a big difference between the spectrum distribution of acceleration response time history and spectrum distribution of strain response time history. Vertical vibration mode made a greater contribution to strain response than horizontal vibration mode.