双层预应力大跨度地铁车站结构震害模拟与分析

以箱型双层预应力大跨度地铁车站开发为研究背景,采用动塑性混凝土损伤本构模型,用拉压损伤因子描述混凝土在循环荷载下的非线性与疲劳性能,综合考虑了震前土-结构自重应力、钢筋混凝土预应力和地铁车站结构的阻尼效应,对土-地铁结构相互作用系统地进行了地震过程的非线性数值模拟.分析了震害发生时大跨度预应力地铁车站结构的破坏过程、破坏形式和抗震薄弱位置.结果表明:地铁车站侧墙底部外侧首先产生裂缝,之后顶板中板在与侧墙连接处、跨中底部等位置出现裂缝,并迅速开展,部分位置甚至形成贯通裂缝;其中靠近底板位置处的侧墙外侧易产生竖向拉压破坏,顶板和中板的跨中及板在与侧墙连接处易产生水平向拉压破坏;侧墙与顶板底板连接处交替出现剪应力集中.靠近底板处的侧墙外侧与顶板在与侧墙连接处上侧位置破坏时间早,因而是影响框架安全的关键部位.

Seismic Simulation and Analysis of the Two-Layer Prestressed Long-Span Subway Station

To develop a two-layer prestressed long-span subway station， a nonlinear seismic numerical simulation of the soil-subway interaction system was conducted， applying the plastic-damage constitutive model to describe the nonlinear and fatigue characteristics of concrete under cyclic loading and taking into account the structural damping and initial stress of the soil-structure interaction system due to the gravity and prestress of reinforced concrete. The destruction process， destruction forms and destruction locations were analyzed after the simulation. The results indicated that the dynamic shear stress concentrates in the external bottom of side walls near to the baseboard， then the mid-span and the upper root of the top board and level board， which can spread fast and even form penetrated cracks in some parts. The dynamic tensile and compression damage emerges easily in the vertical direction of side walls near to the baseboard， and it also emerges easily in the horizontal direction of the top board and level board. The dynamic shear stress concentrates in turn in the junction between side walls and the top board as well as the baseboard. Side walls near to the baseboard and the root of the top board are key parts of a frame for safety where failure tends to occur earlier.