Analysis Of The Interaction Between Suzhou Rail Transit And Adjacent Foundation Pit Project

With the large-scale development of urban metro,the urban agglomeration with metro as the center has gradually developed.On the one hand,there are many large buildings such as shopping malls,houses and stations near the subway.Under the background of new large and medium-sized buildings,more and more excavation projects appear,which affect the safety and stability of subway tunnels.On the other hand,the existence of subway tunnel makes the construction environment of new foundation pit project very complicated,so the influence of tunnel on foundation pit stability should be fully considered.Based on the above two aspects,This paper takes the foundation pit project of Suzhou west bus station as the background,combined with theoretical analysis,practical monitoring and finite element simulation methods,analyzes the interaction between foundation pit project and subway tunnel.Main research contents and conclusions are as follows:(1)Introduce the engineering overview of a foundation pit project in Suzhou,organize and analyze the monitoring structure,ground settlement and subway tunnel deformation data obtained by monitoring the project,summarize the underground continuous wall caused by foundation pit excavation,and the surrounding surface settlement And the deformation law of subway tunnels.The results show that the excavation of the foundation pit has a significant effect on the deformation of the surrounding soil.The foundation pit envelope and the surrounding surface settlement are both parabolic.The lateral deformation of the subway tunnel is greater than the vertical deformation,but they are within the warning range.(2)Based on the actual project,use ABAQUS software to simulate and analyze the actual project,the simulation results show that the simulation data and actual data are more appropriate,indicating that the simulation method in this paper is more reasonable and has a certain predictive effect on the actual project.Subsequently,various parameter changes were designed to conduct in-depth exploration of the foundation pit project and the adjacent subway tunnel.(3)The impact of foundation pit excavation on subway tunnels: The horizontal displacement of the subway tunnel increases with the decrease of the pit tunnel distance,but the increase will be reduced;The maximum vertical displacement first increases and then decreases with the decrease of pit and tunnel distance,which conforms to the soil settlement law obtained by monitoring and simulation;When the mixing pile is removed,the horizontal displacement of the subway tunnel is greatly increased by the excavation of the foundation pit;The influence of the strength of the envelope structure on the vertical displacement of the subway tunnel is much less than that on the horizontal displacement.With the increase of the excavation depth from 8m to 14 m,the horizontal displacement of the subway tunnel increased by about 70% and the vertical displacement by about 76%,indicating that the excavation depth of the foundation pit has a great impact on the horizontal and vertical displacement of the subway tunnel.(4)Influence of subway tunnel on foundation pit excavation: The existence of subway tunnel and the distance of pit and tunnel have little effect on the excavation of foundation pit;The vibration load of the subway will cause the upper and lower fluctuation of the envelope structure.The greater the amplitude of the vibration load of the subway,the closer the vibration load of the subway is to the foundation pit,and the greater the range of the upper and lower fluctuation of the envelope.