Study On The Deformation Characteristics Of Foundation Pit Of Subway Station Airshaft

Because of the size and the complexity of the surrounding environment for Thesubway station foundation pit engineering, its security and stability is extremelyimportant in the process of subway construction. Correctly grasp the deformationcharacteristics in the process of the subway station foundation pit excavation, whichhave important guiding significance to the reasonable design and safety construction.The article based on the background of6#airshaft foundation pit in Hefei SouthRailway Station, and expounded the mechanism of deformation of foundation pitsupporting theory of subway station. Made comprehensive description to the sitemonitoring plan, analyzed to the deep horizontal displacement of retaining structuresystem and the monitoring results around the surface subsidence. By using theFLAC3D finite difference software to set up numerical calculation model, It reproducesthe various conditions of excavation and supporting; using single factor method andorthogonal test method, with the help of the FLAC3D software model to retain theconstruction design factors of pile stiffness. Steel support stiffness, horizontal supportspacing to the influence of the ground settlement around the foundation pit. The mainresults are as following:(1) As the foundation pit excavated, the maximum horizontal displacement of theenclosure occurs at the middle of the foundation pit, the horizontal displacement curvepresents a "convex" shape and the subsidence of surrounding ground become a formlike "concave", the results are in accord with theoretical analysis.(2) The results of numerical simulation and monitoring results of general rule arethe same, and the Numbers are close. Shows that the established model, selectedparameters and the calculation process are feasible. By comparing the area of Sw and Sc,come to a conclusion: the ground settlement was mainly caused by the deformation ofretaining structure, also, both of them are correlated on numerical value.(3)By single factor optimization analysis showed that increasing the steel supportstiffness or retaining pile stiffness and increasing the numbers of steel support canreduce the horizontal displacement of retaining structures and surface subsidence.Through orthogonal experiment design and the result analysis, got the different degreesof the construction design factors are in effect during the deformation of foundation pitexcavation.The researching results provide a reference for the design of subway foundation pit in Hefei as well as other similar projects.