Research On Deformation Law And Stability Of Subway Long And Narrow Deep Foundation Pit

Along with the high-speed development of our national economy, city space is tight with each passing days,3D city space has begun as a kind of important natural resources to be developed. The development and utilization of underground space is the direction of the21st century city construction. Since the nineteen eighties, the development of subway construction is rapid in china cities. At the same time, the subway deep foundation pit engineering is rapidly developing.Deep foundation pit engineering is a marginal discipline with many factors, which is complex. At the same time, it is also a systems engineering. A large number of experiments of deep foundation pit engineering were carried out by domestic and foreign experts, scholars and some successful experiences have been obtained, but the theory is not mature.Deep foundation pit engineering accidents mainly involves two aspects:one is the system instability of deep excavation engineering; the other is the significant change of surrounding environmental conditions caused by deep foundation pit excavation, for example, the surrounding buildings is cracked, even destroyed. These two aspects in the accidents of deep foundation pit engineering are often interconnected. This thesis studies the effects about the stability of supporting structure and the deformation of deep foundation pit excavation, with the methods of theoretical analysis, numerical simulation, engineering example, and so on.The main contents of the thesis are as follows:(1)This thesis summarizes the domestic and international research status about the stability and deformation theory of deep foundation pit engineering, introduces the analysis method of the internal force of retaining structure of foundation pit retaining structure and the relationship between retaining structure and surrounding soil, and discussed the calculation method which greatest impacts the overall stability and heave stability(2) The paper introduces the theory of foundation pit deformation, and analyzes the reasons about upheave deformation of foundation pit, and summarizes the calculation methods on the rebound amount of foundation pit base, derivates the formula of the effect spase of basal heave.(3) Through introducing the finite element theory of excavation engineering and elasto-plastic model for soil, and this text analysises various factors which may impact the influence area of foundation ditch upheaval deformation, with the way of establishing finite element model by MIDAS/GTS software.(4) The text analyzes various factors which may affect the Stability and deformation of excavation engineering, which simulates foundation pit excavation process with finite element method. With the project example of Xingzhengzhongxin subway station excavation engineering, this paper analyzes the results of numerical simulation, at last gives some key construction measures which can control the deformation of excavation engineering.