Monitoring And Numerical Simulation Analysis Of Deep Foundation Pit Support In Urban Tunnel

In order to solve the problem of traffic congestion in the 21 st century,it has become a trend to build urban expressway in various cities in China.As an important component of rapid traffic,the deep foundation pit tunnel has become a research hotspot in related fields both at home and abroad.This article was based on the southern section of the South-North Expressway project in Shenyang city.The stability and safety of the supporting structure during the construction of deep foundation pit were deeply studied with the use of three methods(construction monitoring,theoretical analysis,and numerical simulation).The main research contents are as follows:(1)Based on the geological conditions and climatic conditions of Shenyang region,the monitoring scheme of foundation pit support structure was formulated in combination with the features of supporting structure in this foundation pit.This monitoring was combined with automated monitoring and manual monitoring.The principle and method of monitoring the contents of the monitoring has been thoroughly analyzed and explained,which was the foundation for the safety construction,monitoring and analysis of the foundation pit.(2)All timely objects were obtained at the spot,and they were deeply analyzed,meanwhile the excavation of the objects with excavation of foundation pit were obtained,and the reason about the variation was analyzed.Also,the function and influence of various factors with the excavation in each phase was determined.However,the deformation of supporting structures and mechanical behavior was deeply analyzed in the foundation of the objects.Also,it made a warning about the security and stability of the foundation pit.(3)According to the geological prospecting information,the three-dimensional finite element model was established by using the finite element software Midas/GTS for the construction section(SK1+850~SK1+885)which was representative of the tunnel engineering.The axial force of steel support and the deformation of retaining structures at each stage during the construction of deep foundation pit support structure are obtained by numerical simulation analysis.(4)The simulation results were consistent with the measured data,which were obtained by comparing the simulated results with the measured data.The results of monitoring data and numerical simulation of the project were verified normally.At the same time,it also helped designers and builders to understand the deformation rules of foundation pit support structures.It also provided references for the design and construction of deep foundation pit in Shenyang and similar areas.To sum up,the deformation and mechanical properties of the supporting structure system in the construction stage of deep foundation pit were studied with the use of three methods(construction monitoring,theoretical analysis,and numerical simulation).The research of this paper had obtained beneficial results,which could provide a reference for the optimization design and structural analysis of similar projects.