Numerical Analysis Of Deep Subway Station Pit For Mixed-support Structure Of Internal Bracing And Anchor Rope In Strata With Soil-rock Stratum

With the development of economy of our country, subway plays a vital role inoverall arrangement of a city, the depth and difficulty of deep foundation pit of subwaystation is increasing. The study on the force and deformation law of enclosure structurein deep subway station pit is one of the important subjects in deep subway stationconstruction. It is most valuable to research the deformation rule of enclosure structurein deep subway station pit, by using the methods of field monitoring and numericalsimulation. Based on the Huiquan Square Station of Qingdao Subway branch3, theconstruction process of the deep foundation excavation is simulated and analyzed usingthe special geotechnical software PLAXIS，the force and deformation law of structureof deep subway station pit are studied. The main jobs and conclusions are as follows:(1) This article described the main features of foundation pit structure and thedeformation rules in deep subway station construction, and analyzed the inner and theexternal influence factors. The results show that the main affection factors includesupporting conditions, the stiffness of underground continuous concrete wall,engineering geology and hydrology geology, construction procedures and constructioncircumstance.(2) According to analyzing the in-situ monitoring data, this paper researched thedeformation laws of underground continuous concrete wall and the variation ofsupporting axial stress.(3) The two-dimension elastic plastic finite element analytical model wasestablished for this deep subway station pit, and according to the actual conditions inwork-site, the stress and deformation of underground continuous concrete wall and thesupporting axial stress are calculated and analyzed by plate finite element method.Finally, according to compared with field monitoring data of the horizontaldisplacement of retaining structure. With numerical simulation, many factors, including the diameter and the soldier piles, support changing, which may affect the stress anddeformation of underground continuous concrete wall. By the simulation, thedeformation rules of these factors are got, some conclusions are proposed for the designand construction of deep foundation-pit in deep subway station.