【作者】 刘杰；

【导师】 任建喜；

【作者基本信息】 西安科技大学 ， 结构工程， 2008， 硕士

【摘要】 地铁车站基坑围护结构设计及其稳定性分析研究是黄土地区城市地铁建设中的关键课题之一,开展黄土地区地铁车站深基坑围护结构变形规律研究具有重要的价值。本文以某城市地铁车站深基坑工程为依托,采用理论分析、现场监测和有限元模拟相结合的方法,对地铁车站深基坑稳定性及其围护体系变形规律进行了研究。主要工作有:(1)研究了深基坑的变形机理及破坏模式,分析了影响深基坑稳定的主要因素。结果表明,在开挖过程中,基坑围护结构的应力、变形随着时间、空间的变化不断变化,即深基坑开挖过程中存在明显的空间效应。影响基坑围护结构变形的主要因素为:土压力、水文地质条件、支撑条件、围护结构的刚度、土层强度、地下水等。(2)完成了对基坑围护结构方案及监测方案的设计,对基坑的围护结构变形规律进行了现场监测研究。重点分析了基坑施工过程中围护结构的变形规律、基坑周围地表竖向变形随基坑开挖深度和时间的变化规律。监测结果表明:钢支撑和围护结构对围护结构侧向变形有一定限制作用,围护桩的水平位移、地表竖向沉降均小于设计值,围护结构的设计偏于保守,但对于工程来说是安全的。(3)采用弹塑性有限元分析方法建立模型对地铁车站深基坑开挖进行了施工仿真模拟,将围护结构水平变形及基坑周围地表竖向变形计算结果与实际监测结果进行了对比,二者比较吻合,说明有限元计算的结果是可信的。(4)采用有限元法研究了围护桩入土深度、钢支撑架设的位置和土层的力学特性对地铁车站深基坑稳定性的影响规律。更多还原

【Abstract】 The study of design and stability analysis of retaining structure in subway station deep foundation-pit in loess area is one of the key subjects of construction of subway station in loess area.The study of deformation law of retaining structure in urban subway station foundation-pit in loess area has important value. This article is based on some urban subway station foundation-pit project, use the manner of combine assume study of theory, deformation law of retaining structure in urban subway station foundation-pit is studied by in-situ monitoring and FEM simulation. The main jobs are as follows:(1)The deformation mechanics and destroy pattern of deep foundation-pit is studied; the main impact factor of deep foundation-pit stabilization is analysised. When the excavation begins, the deformation and earth pressure of the retaining structure in the foundation-pit will change accompany to the time and space’s changes. It is to say that the process of the foundation pit excavation existences time and three-dimensional effect. The result indicates that: the main impact factors of retaining structure of retaining structure are earth press hydrographic geology condition, poling condition, retaining structure stiffness, strength of soil horizon, ground water condition and so on.(2)The design of monitor scheme and retaining structure in foundation-pit scheme is completed,in-situ monitoring of deformation law of retaining structure in deep foundation-pit is preceded.The deformation law of retaining structure construct process is emphasis analysised,alteration law of the veritical deformation of ground surface soil body follow the depth and time of deep foundation-pit excavation .the result indicates that the steel shotcrete and retaining structure have limite action to soil body lateral deformation.In the process of excavation of the foundation-pit, the horizontal displacement of fender post and vertical displacement of ground surface are all less than design value, it illustracts that the design scheme is comparatively conservatism, but it’s safe to the engineering.(3)Elasto-plasticity finite element analysis method is given to model to simulate construction process for subway station deep foundation-pit excavation.Compare the calculation result to practice monitor result of retaining structure horizon deformation and vertical deformation of ground surface soil body, they are anastomotic, the result counted by FEM is credibility.(4) The FEM simulation is used to study the law of the effect of urban subway station deep foundation-pit stabilition in loess area by changing of the foundation-pit fender post depth in the soil, the position of the steel shotcrete and soil body mechanics character of loess .更多还原