Research On Deformation Monitoring And Control Technology For Deep Foundation Pit Of Open Cut Metro Station

With the gradual progress of the country’s urbanization process,the demand for the development of urban underground space is increasing day by day,more and more cities have begun to develop urban rail transit construction,and open cut construction has become a widely used excavation in the construction of subway stations The method has the characteristics of simple construction,short construction period,and economy.However,because the subway station is usually located in the city center,the surrounding environment is very complicated,and the problem of deep foundation pit deformation and ring breaking occurs frequently.Through the combination of theoretical analysis,monitoring and measurement,and numerical simulation research methods,relying on the Jinan Yellow River Tunnel Project,to study the deformation law of deep foundation pits in open-cut subway stations,and propose deformation control measures.The research conclusions are as follows.(1)Based on the scholars’ research results on the deformation law of deep foundation pits,through theoretical analysis,analyze several major deep foundation pit supporting structure forms,study the deformation law of the deep foundation pit retaining structure,the rear of the retaining structure The vertical deformation law of the soil,the deformation law of the base uplift and the change law of the axial force of the inner support determine the deformation calculation method of the deep foundation pit.(2)Based on the Jinan Yellow River Tunnel Project,based on the geological conditions and hydrogeological conditions of the construction site,a construction monitoring plan was formulated,the layout of the monitoring points was introduced,the monitoring and measurement data were integrated,and then research and analysis were carried out Ground subsidence,deep horizontal displacement of the underground continuous wall,displacement of the top of the underground continuous wall,and the variation of the axial force of the internal support.(3)Through the numerical simulation software FLAC3D,combined with the actual excavation of the deep foundation pit project,a deep foundation pit excavation model is established,which simulates the deformation of the enclosure structure and the surrounding soil vertical during the excavation of the deep foundation pit Lateral displacement,and then through comparative analysis with on-site monitoring and measurement data,obtained a series of deformation laws of deep foundation pits such as the surface settlement curve is funnel-shaped,the deep horizontal displacement curve of the underground continuous wall is convex to the right,etc.(4)Three major factors influencing the deformation of deep excavation in open excavation were studied.The model working conditions were modified by numerical simulation,the influence of the sequence of support excavation on the deformation of deep excavation was studied,and the deep excavation was proposed based on the actual project Specific measures for deformation control.