| ABSTRACT:With the rapid development of Chinese economic, city urbanization, city population and vehicles increment have bring great pressure to the city traffic. As the subway transportation has high efficiency, it will be developed rapidly in Chinese city There are many methods for subway construction, because of its characteristics of high safety and less disturbance to traffic, Covered Excavation method has been widely used in subway station construction in city crowded area. The main research contents of Covered Excavation method is how to control the deformation of foundation pit during the excavation process to ensure the safety.This paper is depend on the project of Qingdao Wusi square subway station. Firstly it introduces the development of Covered Excavation method and the research status. Based on the analysis of the key technical problems and the advantages and disadvantages about the three kinds of Covered Excavation method, combined with the practice of the project, choose the semi-inversed Covered Excavation method as construction method. The mechanism of deformation during subway station excavation are analyzed. The main factors that affect the deformation of foundation pit and the theory of foundation deformation calculation methods are described, and introduced the foundation pit retaining structure and its deformation features. Use Midas GTS to calculate and established2D and3D models based on the subway station. Compare with the calculate results about the foundation pit deformation and the in-situ monitoring results, analysis the deformation features during excavation. Calculate and analysis the deformation features of suspending pile. Finally, introduced the conception of the deformation alarming of the foundation pit and the important meaning on restricting the deformation of foundation pit, put forward the deformation alarming control standards based on monitoring data and engineering data, and applied to actual project. |
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