软土层埋深变化对地铁车站结构地震反应的影响规律研究

Earthquake responses of subway station with different depths of soft soil

软土侧向大变形将是造成地铁车站结构严重震害的主要因素。为了明确软土层埋深对地铁车站结构地震反应的影响规律,对常见的两层三跨岛式地铁车站结构侧向和底部地基中存在不同埋深软土层时5种软场地和1个一般场地条件下地铁车站结构的地震反应进行了数值模拟分析。计算中采用自行建立的软土记忆型黏塑性动力本构模型模拟软土的动力非线性特性,混凝土的动力特性采用黏塑性动力损伤模型。给出了软土层不同埋深对地铁车站结构的加速度反应、侧向摆动位移反应和应力反应的影响规律,为提高软土地基上城市地铁车站结构的抗震性能及其抗震设计方法提供了依据。

The large lateral displacement of soft soil layer is the main factor to cause the severe earthquake damage of subway stations. To confirm how the depth of soft soil layer affects the earthquake responses of subway stations, the finite-element method is used to model the dynamic interaction system of soil-subway station when five soft sites and one general site are used as the foundation of subway station respectively. The nonlinear dynamic properties of soft soils are modeled by the dynamic visco-plastic memorial nested yield surface model developed by the authors. The dynamic viscous-plastic damaged model is used to model the characteristics of concrete under cyclic loadings. The acceleration response, displacement response and stress response of subway stations lying in different soft sites are compared with those corresponding responses of subway stations lying in the general site. Many important results are given in this paper and the research achievements can be used in the seismic design of subway stations built in soft soil layers.