Field Monitoring And Numerical Simulation Of Deep Foundation Pit Excavation In Metro Station

This paper takes the excavation project of the conference center station of Shenzhen convention and exhibition center as the research object,monitors and measures the horizontal displacement and deformation of ground connection wall,the axial force change of concrete support and steel support,and the vertical displacement of the outer surface of the foundation pit.Based on the design of drawings and the geological and hydrological conditions,the foundation pit engineering of the station is modeled,and the construction of the deep foundation pit of the station is numerically simulated,and the deformation and displacement of the ground connection wall,the change of the axial force of support and the vertical displacement of the outer surface of the foundation pit in the construction of the subway station in the coastal soft soil area are studied.1.According to the current development status of deep foundation pit,the types of foundation pit deformation are analyzed and studied,which mainly include wall deformation,surface settlement,foundation pit uplift deformation and support axial force change.The construction technology of foundation pit excavation is much the same,but because each station is located in a different location,its surrounding environment,geological structure,hydrological conditions are different,the adoption of the support system is also different.2.Research on types of subway envelope structure,excavation method of soil in station foundation pit and types of envelope wall.The settlement and deformation mechanism of the surrounding soil and retaining structure of the subway station foundation pit,the basic types of the foundation pit deformation of the subway station,the main influencing factors of the foundation pit deformation of the subway station,how to control the foundation pit deformation of the subway station,reduce the deformation influence of the foundation pit of the subway station,and ensure the safety of the foundation pit.3.The foundation pit project is characterized by complex geological environment,complex engineering technology,strict monitoring standards and high construction risks.The underground excavation of deep foundation pit is complicated andundetectable.Detailed geological survey should be carried out before excavation.Therefore,in the early stage of excavation,during the excavation process and in the later stage,it is necessary to closely monitor the changes of various data,timely process and analyze the monitoring data,and timely feedback the analysis results,so as to implement the informatization construction and provide guarantee for the safe excavation and construction of the foundation pit.Therefore,dynamic monitoring and measurement of foundation pit supporting structure and surrounding conditions should be carried out during earthwork excavation to ensure the smooth construction of foundation pit earthwork excavation.Main monitoring items: horizontal displacement monitoring of the enclosure wall,vertical displacement monitoring of the surrounding ground surface,axial force monitoring of the support,horizontal displacement and vertical displacement monitoring of the top of the wall.4.Using MIDAS GTS NX numerical simulation analysis software,the subway station is used to numerically simulate the supporting structure and surrounding soil,selection of the palisade structure of the rational constitutive model and hydrogeological parameters,analysis of retaining structure,the author analyzes the construction phase of the ground settlement around the foundation pit excavation and retaining wall deformation,supporting axial force and deformation of foundation pit uplift changes,etc.,research in earthwork excavation process of foundation pit deformation law of foundation pit and its surrounding.