Study On Stability And Deformation Control Of Deep Foundation Pit In Subway Station

Due to the rapid development of China’s economy, along with the accelerating urbanization and the steady advance of urban-rural integration, the urban traffic and environmental problems is increasingly prominent. In order to solve the problem of traffic congestion, more and more cities in our country began to plan and build rail transit projects. Because of the continuous construction of rail transport projects, the foundation pit project presents the characteristics of “a deeper depth, a larger scale, and more complex surrounding environment”. The complex surrounding environment brings up higher requirements on the stability of foundation pit. Therefore, it is of vital and practical significance to study the stability of deep foundation pit slope.In this thesis, the author chooses the deep foundation pit engineering of Hualong station of Chongqing rail transit to analyze the deep foundation pit of Subway Station Excavation and deformation by means of theoretical analysis, numerical simulation, field monitoring and other research methods. The main work is done as follows:(1)In this paper, the characteristics and the difficulty of the construction of deep foundation pit engineering was analyzed. The construction scheme and monitoring scheme of deep foundation pit are introduced. The deformation of foundation pit is monitored during construction.(2)Various analysis methods of foundation pit slope stability are briefly introduced. Based on the construction practice and by means of both theoretical and numerical analysis, the stability of unsupported excavation of the slope stability are analyzed.(3)Combined with the area of thicker fill in the end of the station, the author first uses the limit equilibrium methods to analyze the stability of this area; next, the author establishes finite element model and analyzes the rule of deep foundation pit supporting structure and surrounding ground deformation under different construction condition.(4)Considering the circumstance that the rock section area of the station has thin soil layer, the author, firstly, combined with the existing specifications calculation, introduces the failure mode of rock foundation pits; and then, analyzes the stability of the rock foundation pit by means of theoretical analysis; based on these, the author then built numerical model through finite methods to analyze the deformation and failure mechanism of the slope of the rock foundation pit; finally, the thesis makes related conclusions through the analysis of the effect of the supporting measures by field monitoring data.(5)The thesis, through the establishment of three-dimensional finite element model of pile and strut supporting system of Deep Excavation, studied the pressure and deformation of supporting structure(concrete continuous wall, steel support, support), the results of which can provide guidance for the deep foundation pit construction.To sum up, this thesis applies the theoretical research and numerical simulation to the practical engineering and proves their consistency by field monitoring data. The research findings of this thesis have a certain reference value for the design and construction of similar projects.