Finite Element Simulation And Field Monitoring Analysis Of Deep Foundation Pit Of A Subway Station

The development of urban rail transit has a long history,and the deep foundation pit project of subway station is a significant engineering,which has attracted high social attention.But the theory and technology of foundation pit engineering are not perfect;besides,the construction conditions as well as the surrounding environment are so complex.It is necessary to take a study on the deep foundation pit of the subway station to ensure the safety of the construction process.The paper had simulated the whole process of foundation pit excavation by the way of numerical simulation and compared the calculated results with the field monitoring data based on one subway station deep foundation pit engineering.The main contents and conclusions are as follows:(1)Building the three-dimensional calculation model by MIDAS/GTS Finite Element Software to simulate the whole excavation process,the paper had analyzed deformation properties of deformation of retaining structures as well as bottom uplift,surface subsidence and the influencing factors of the deformation of the retaining structure,The results show that the horizontal displacement of the envelope is increased firstly and then decreased with the increase of excavation depth and the horizontal displacement of the envelope got highest When the foundation pit was excavated to the end,which meet the specifications and design requirements;surface settlement curve is first increases and then decreases,finally tends to be stable gradually "parabolic" form in the process of excavation,and the surface settlement reaches the maximum when the excavation was at the end,which meet the specifications and design requirements;The closer to the foundation pit center,the greater the amount of bottom uplift,the end of excavation at the end of the bottom uplift reached the maximum,which meet the specifications and design requirements;increasing the internal support stiffness and the thickness of the underground continuous wall can suppress the horizontal displacement of the envelope effectively.(2)The representative monitoring points of the foundation pit are selected,which mainly analyzes the monitoring data of the surface subsidence and axial force of three steel pipe support.The monitoring data meet the specifications and design requirements,indicating that the design of the building envelope is reasonable and effective.The numerical simulation results are in high agreement with the measured results,which indicates that the calculation model is reasonable.The numerical simulation results can provide reference for the design of the envelope and foundation pit monitoring scheme.