Supporting Design Of Deep Foundation Pit In Sandy Soil And Deformation Analysis Of Surrounding Structures

Coastal areas are developed economically.The soil layer represented by sand soil layer and silt layer is a common soil layer.However,there are few analysis on the support design of sand soil in the rich water area.Based on a practical project of Shanghai Metro,the design scheme of support is compared and selected.After that,the horizontal displacement of retaining piles obtained by the analysis of the measured monitoring data and finite element simulation analysis and the horizontal displacement of the retaining pile are obtained The data of ground settlement deformation and surrounding buildings deformation verify the rationality of the support scheme,and analyze the influencing factors of foundation pit support structure and the deformation law of foundation pit.The main contents and main achievements of this thesis are as follows:1.The thesis compares and selects the support scheme for the actual project,and makes the monitoring plan according to the selected support structure scheme,arranges the statistical monitoring data,systematically analyzes the monitoring data of the surrounding buildings and structures deformation,the displacement of the retaining wall,the ground settlement and the change of the supporting axial force,and verifies the rationality of the comparison principle of the support scheme in this thesis.2.Based on the results of finite element analysis and foundation pit monitoring data,the horizontal displacement of retaining piles,ground settlement deformation and surrounding buildings deformation are mainly analyzed.It is found that the horizontal displacement of the retaining wall of the foundation pit is in the form of "bow" displacement,the middle part of the foundation pit is the largest,and the ground subsidence of the foundation pit is closely related to the deformation of the building,The settlement position of the ground increases in a certain range from the foundation pit.3.The deformation prediction of the foundation pit under three types of retaining structure,i.e.the internal steel TRD cement wall,the underground continuous wall and the cast-in-place pile,is carried out by Midas GTS finite element software.The analysis results show that the deformation development of the foundation pit can be effectively controlled by increasing the rigidity of the retaining wall,reducing the vertical spacing of the supports and applying the preloading of the axial force.