Analysis Of Influence Of Deep Foundation Pit Excavation Method On Support Structure And Surrounding Rock

With the development of society and the needs of urban construction,the foundation pit engineering is a vital part of the building construction process.The excavation methods and calculation methods are more and more diversified.The common excavation methods have grading.Digging,basin excavation,center island excavation,etc.Support forms often used in engineering include row piles,floor-connected walls,soil nail walls,and so on.Especially important in the process of foundation pit excavation is a control of the overall deformation of the foundation pit,and different excavation methods have different effects on the deformation of the foundation pit.This paper discusses three excavation methods:segmentation The effects of stratified excavation and full-section excavation on the deformation of foundation pits are emphasized.The dynamic process of excavation during excavation is emphasized.According to the change law,some suggestions for monitoring operations during excavation are proposed.This paper combines Hefei Metro Line 4,Susong Road Station foundation pit excavation and other related materials to reveal the dynamic process of soil and foundation pit support structure during foundation pit excavation;based on engineering cases and measured data,use large-scale general The software Midas establishes a numerical model and compares it with the actual data.The model is used to study the dynamic variation of different excavation methods during excavation.The following conclusions were drawn:1.The effect of segmental layer excavation on the foundation pit is smaller than that of the whole section.The surface settlement caused by segmental layer excavation and the deformation of the retaining structure are less than the surface subsidence and deformation of the retaining structure caused by full-section excavation.2.Based on the special excavation method of the project,after the excavation of the foundation pit in the first and east sections,the settlement of the surrounding soil presents a small end,the middle is large,and the deformation of the retaining structure is also the same.The deformation of the end is small,and the deformation in the middle is large.3.After the excavation of the foundation pit in the western section,the 8th section,the7 th section,the 6th section,the 5th section,the 5th section and the 4th section,a certain sudden change occurred in the retaining structure of the foundation pit within 60 m to 108 m from the west end of the foundation pit.The soil settlement in this part is also too large.Mainly because the blocking piles in the third and second sections and the part of the soil limit the deformation of the retaining structures in the third and second sections,resulting in excessive deformation of the right side of the foundation pit in the range of 60 meters to108 meters.4.The settlement of the soil surrounding the foundation pit excavated by layered excavation and the deformation of the retaining structure are developed into a propulsion type,which is consistent with the direction of excavation,and the deformation of the soil and retaining structure around the full-section excavation In the overall descending type,as the excavation progresses,the surrounding soil and the two side envelope structures aredeformed as a whole.