软土场地地铁车站结构地震反应特性振动台模型试验

作为地铁车站结构地震破坏机制大型振动台系列模型试验之一，开展了近、远场强地震动作用下软弱粉质黏土场地框架式地铁车站结构体系的大型振动台模型试验。测试分析了模型地基的加速度、孔压、地表震陷和模型结构的加速度、应变、水平位移反应等。结果表明：地震波在模型地基的传播过程中呈现出自下而上低频增大、高频减小的现象；强地震动作用下模型地基的基频明显降低，呈现出明显的低频聚集（放大）、高频滤波效应；模型地基的孔压比增长较小，在不同特性地震动作用下模型地基孔压比的发展过程存在较大的差异，并显示出显著的空间效应；近、远场地震动作用下模型地下结构的加速度反应存在明显差异，模型地下结构对软土地基地震动加速度反应的影响具有显著的空间效应；模型地下结构相对变形小、未出现明显上浮现象，地震动频谱特性对其侧墙的变形模式和大小存在显著的影响；模型结构中柱为地震损伤最严重部位；模型结构整体损伤情况较轻、处于非破坏状态。

Shaking table test on seismic response of subway station structure in soft ground

As one of the series large-scale shaking table tests on the failure mechanism of subway station structure, a large-scale shaking table test on frame type subway station structure model in soft silt clay under near- and far-field strong ground motions is conducted, in which the acceleration, pore pressure and earthquake-induced settlement of the model ground as well as the acceleration, strain and horizontal displacement of the model structure are measured and analyzed. The results show that as the seismic wave propagates in the model ground, the amplitude of the low frequency components increases while the amplitude of the high frequency components decreases from the bottom to the top of the ground. Under strong ground motions, the fundamental frequency of the model ground significantly decreases, and the ground exhibits a remarkable amplification effect for low frequency components and wave filtering effect for high frequency components. The pore pressure ratio of the model ground slightly increases. The development processes of pore pressure ratios under different ground motions are greatly different, and show an obvious spatial effect. Under near- and far-field strong ground motions, the acceleration responses of the model structure are obviously different. The model structure has a significant spatial effect on the acceleration response of the ground motion for the soft ground. The frame structure does not show an obvious floating phenomenon and its relative deformation is small. The frequency characteristics of the ground motion have an obvious influence on the deformation mode and magnitude of the side wall for the model structure. The most severely seismic damage part is located at the middle column of the model structure. The whole model structure is slightly seismic damaged and in nondestructive state.