Influence Of Excavation Of Sandy Silt Deep Foundation Pit On The Deformation Of Surrounding Soil

Since the 21 st century,with the rapid development of urban rail transit,the number and construction difficulty of urban underground engineering are gradually increasing.Subway station is usually located in the prosperous area of the city,the surrounding buildings are relatively dense,and the engineering environment is complex.In the construction of the project,the impact on the surrounding environment should be reduced as much as possible,and the impact on the surrounding buildings and the settlement of the surrounding soil should be controlled within the safe range,so as to avoid property loss caused by accidents.In this paper,Wuxi sandy silt deep foundation pit project as the research object,through the combination of field monitoring and numerical analysis,the deformation law of soil around the foundation pit during the excavation construction is studied.The main research results include the following four aspects.(1)The excavation of foundation pit will cause settlement of soil outside the retaining structure.The surface settlement curve is a "groove" shape,and the maximum surface settlement is about 0.07% of the current excavation depth.Under the influence of precipitation and excavation,the surface soil moves horizontally towards the foundation pit.With the progress of excavation,the external surface horizontal displacement of the foundation pit increases.(2)With the increase of excavation depth,the horizontal displacement of retaining wall increases gradually,and reaches the maximum deformation at the bottom of the foundation pit.Due to the limitation of soil mass,the deformation of deep wall under the pit bottom decreases gradually,and the deformation curve is "bow".(3)Unloading after excavation of foundation pit results in uplift and deformation of soil at the bottom of foundation pit.The uplift curve of the whole section is in the shape of "arch",and the uplift value of the middle part is the largest.The closer to the retaining structure,the smaller the soil uplift.(4)Three engineering factors,such as geological conditions,support form and retaining structure stiffness,will have a certain impact on the surrounding soil deformation in the process of foundation pit excavation.The foundation pit engineering with poor geological conditions is greatly affected by the excavation of foundation pit.The wall crown beam and internal support have obvious limiting effects on the deformation of the soil around the foundation pit.Increasing the stiffness of diaphragm wall can reduce the surface deformation around the foundation pit and the deep deformation of soil around the foundation pit,but it is not economic and reasonable to control the surface deformation by increasing the stiffness of diaphragm wall.This paper has 62 figures,16 tables and 82 references.