Analysis Of Deep Excavation Anti-float Structure Design In Typical Wuhan Subway Stratum

In order to meet the requirements of developments of China's urban rail transit development, underground rail transit in all the primary cities and some second-tier cities of China are established, the deep cut-covering in urban is inescapable, and so it is very important and necessary to ensure the stability and safety of deep pit anti-floating in some cities where the line of ground water is high and have various underground water, for instance:Wuhan, Shanghai, Nanjing. Attach the diaphragm wall with main structure of subway station to anti-floating is an advanced technology in deep pit anti-floating, but also the most common, most economical and most effective method, at the present stage, it's widely used in Wuhan subway station. So study on the safety of deep pit anti-floating structure like this type has very important theoretical significance and practical meaning.In order to study the applicability of the anti-floating design method like this in Wuhan, by analysis the data of the hydrogeology in Wuhan, choose the representative first terrace in Wuhan to be object of study. This paper is based on the deep pit of Fanhu station in Wuhan metro second line, according to diaphragm wall and main structure in actual engineering, do a series of research by combine theoretical analysis with numerical simulation, and get some helpful conclusion.Firstly, on the base of collected related articles, direct at deep pit anti-floating measures at present, compared various merit and demerit of anti-floating measures and the situation they suit for. Summary the theoretical formulas about deep pit anti-floating, compared and analyzed the fundamental assumption and rationality of various theories.Secondly, in order to report typical stratum structure in Wuhan better, comprehensive analyzed stratum structure, engineering geology and hydrogeology in every area of Wuhan, and compared hydrogeology of first, second and third terrace of Quaternary Period settled layer, and knew that pressure water in first terrace is the most harmful in deep pit anti-floating in Wuhan, therefore, chosen Fanhu station in second line of metro to be project case to analysis.Finally, chosen the most representative Fanhu station in second line of metro to be project case, used finite element software ANSYS to established the model of plane strain, proved the safety and stability of this anti-floating design by analyzed numerical simulation of two case:without buoyancy under main structure of subway station and with the highest underground water level presses under main structure of subway station. And used finite difference software FLAC3D analyzed the process of pit excavated and underground water level risen by simulation. Fully proved combined diaphragm wall and main structure ensure effectiveness of stability of subway station by analyzed displacement, stress and stability.