Study On Stability During Construction Of Deep Foundation Pit For Ti Yu Zhong Xin Subway Station In Xi'an

Due to the advantages of large traffic volume,fast speed,clean environment protection and so on,the subway has become the best solution to realize " Slow plugging" and "smooth flow protection" in a certain scale city in China.With the rapid development of China's urban subway network,the proposed subway itself and its surrounding environment are more complicated,and the difficulty of building deep foundation pits in subway stations is also increasing.The construction of the deep foundation pit of the subway station must ensure the safety and stability of the entire supporting system during the excavation of the foundation pit.Within the specified range,the foundation pit does not suffer from normal use instability.In this paper,the foundation pit retaining wall retaining structure is the research object,relying on the deep foundation pit engineering of Xi'an Ti Yu Zhong Xin Subway Station row pile and inner support structure to study the stability problem in foundation pit construction.The main work and research results of the thesis are as follows:1)Study on the instability of the foundation pit support structure caused by the soil parameters and groundwater in the con struction process of the retaining wall retaining structure and the instability of the support system due to the design parameters of the foundation pit support structure Destruction of these two types of foundation pit engineering instability mode.This paper summarizes the research progress made by domestic and foreign scholars in the research methods of foundation pit stability.2)Relying on the deep foundation pit project of Xi'an Ti Yu Zhong Xin Subway Station,this paper introduces measures of deep foundation pit stability control,selects the deep foundation pit support scheme,introduces the design of the foundation pit support system in the row pile and inner support structure form,and formulates the foundation pit.Formulates the construction plan for the excavation method of the foundation pit project.3)The construction of the deep foundation pit of Xi'an Ti Yu Zhong Xin Subway Station was simulated by MIDAS GTS finite element analysis software.The safety factor of the foundation pit during the whole construction process is greater than 1.3.During the construction of the foundation pit,the maximum horizontal displacement of the retaining structure is 7.48mm,and the maximum axial forces of the raft support and the one-to-three-layer steel support are 496.3kN,489.4kN,1539.4kN,and 1667.6kN,respectively,and the horizontal displacement and settlement of the viaduct are the largest.The values are 6.65mm and 5.43mm,the maximum surface settlement is 13.2mm,and the maximum uplift of the foundation pit is 32.4mm,which does not exceed the warning value.The safety factor of the foundation pit during the whole construction process is greater than 1.3.The research shows that the design of the whole foundation pit does not show normal use instability during the excavation process and has high stability.4)Developing a deep foundation pit monitoring plan to analyze the horizontal displacement of the retaining structure,the supporting axial force,the surface settlement within the monitoring range of the foundation pit and the horizontal displacement and settlement monitoring data of the viaduct.The monitoring values are all normal.Within the limit state control value,the foundation pit has a high stability during the excavation process.Comparing the monitoring and numerical simulation data,it is proved that the measured data related to the stability of the deep foundation pit is close to the numerical simulation analysis results,and the analysis results better predict the deformation stability of the foundation pit supporting structure.5)Based on the research under design conditions,considering the influence of foundation pit excavation on the surrounding buildings(structures),the main influencing factors of the stability of deep foundation pits are analyzed by numerical simulation:pit side load,steel support and enclosure The influence of structural design parameters and soil physical properties on the stability of foundation pit provides a reference for the construction of similar projects.It provides reference for the construction of similar projects,and provides an optimal idea for the stability control during the construction of similar projects from the project management system.