Analysis And Control Method Of Uneven Rebound Annular Plate In Top-Down Method Of Deep Foundation Pit

For cover excavation foundation pit,the soil at the bottom of the foundation pit is always restricted by the piles.On the one hand,the piles restrict the rebound of subsoil and make the different rebound in different aere between the piles and the diaphragm wall wall.At the same time,the upper parts of the piles are bound by the horizontal structure beam slab.Subsoil unloading will make different positions of piles and underground continuous wall settlement and uneven uplift.It impact on the supporting system of foundation pit and makes an additional axial force in supporting column.It leads to horizontal floor collapse when the support column instability.To have the support column within the support,the supports of additional moment caused by rebound make the columns have additional moments,and the slabs easy to crack under an excessive additional moment.So it makes higher requirements of the cover-reverse entire support system on the difference deformation.And it brings a greater degree of difficulty to the design and construction of the support system.How to predict rebound of the foundation pit accurately before the excavation is the engineering problem of the design of cover excavation foundation pit.This paper intends to carry out the following research work on the inverse method of springback:(1)Analysis of measuring data of the rebound of cover excavation foundation pit.Combined with the MinQuan Gate Subway Station project,this subject is proposed to measure the rebound and the influence of the cover excavation foundation pit.Mainly carried out: analysis of measuring data of soil pit rebound,analysis of measuring data of structural slab stress,analysis of measuring data of diaphragm wall vertical displacement,analysis of measuring data of differential settlement between columns.By monitoring the process of the project,make a sense of the amount of resilience of the soil and support system,and its influence on the architecture.(2)Comparative analysis of result of finite element model and measured dataIn this paper,finite element model was established based on the practical project to study the deformation of the diaphragm wall and the settlement of the surrounding soil and pile pillar.To verify the accuracy of result of the finite element model simulations,is in order to provide a reliable finite element simulation analysis.(3)Control measures study of ring plate rebound in Top-Down method of deep foundation pitBecause of past experience and engineering field test,a certain amount of resilience and uneven rebound is found in different parts of the vertical envelope structure and the level of support,through numerical simulation investigate and solve the issue of how to eliminate the secondary stress of the structure caused by uneven rebound.Setting different supporting piles in different parts of the pit,Changing pile diameter,pile length in different parts of the pit and grouting measures are methods to control uneven rebound annular plate in top-down method of deep foundation pit.