基于振动台试验的黄土场地具有地上结构地铁车站地震反应特性分析

Seismic Response of Subway Station with Above-Ground Structure in Loess Field Based on Shaking Table Test

以兰州某地铁车站为研究背景,开展了黄土场地具有地上结构的地铁车站结构体系大型振动台模型试验。测试并分析了模型体系的基频、加速度和水平位移反应以及模型车站的应变和侧墙处的动土压力反应等。结果表明:浅层地基土及埋置于其中的模型车站地下结构的加速度反应对地震动频谱特性具有较高的敏感性,而深层地基土及模型车站地上结构的加速度反应对地震动频谱特性敏感性较低;在土-结构动力相互作用过程中,地基土与地下结构运动方向相反,地基土对地下结构的变形起到“主动”约束和限制作用;结构地上第一层中柱底部是地铁车站的最薄弱部位;模型结构侧墙处动土压力增量在深度方向的变化规律受地震动强度及地基土弹塑性状态的影响。

A large-scale shaking table test based on a subway station with an above-ground structure on the Lanzhou Metro under the condition of a loess site was conducted.The effect of the fundamental frequency,the acceleration,the horizontal displacement of the model system,the strain of the model structure and the dynamic soil pressure response of the model foundation were considered in analysis.The acceleration response of the shallow foundation soil and the underground structure of the model station embedded therein was highly sensitive to the frequency characteristics of the ground motion,while the acceleration response of the deep foundation soil and the above-ground structure of the model station was less sensitive to the frequency characteristics of the ground motion;In the soil-structure dynamic interaction process,the movement of the foundation soil and the underground structure was in the opposite direction,and the foundation soil had an active constraint and limitation on the deformation of the underground structure.The bottom of the column at the first storey above the ground was the weakest position of the subway station structure.The change of the dynamic soil pressure increment along the depth of the model structure was affected by the intensity of the ground motion and the elastoplastic state of the foundation soil.