Research On The Influence Of Deep Foundation Pit Excavation On The Deformation Of Adjacent Pile Foundation Buildings In Soft Soil Area

With the progress of foundation pit construction,the relationship between engineering construction and surrounding environment is increasingly close.There are more and more adjacent buildings in deep foundation pit construction.The influence of soil displacement caused by foundation pit excavation on adjacent buildings has attracted extensive attention.Therefore,deep foundation pit excavation should not only ensure the stability of its own structure,but also ensure the safety of adjacent buildings.In view of the case study of the deep foundation pit of Jinan Yellow River Tunnel automobile repair factory,based on the methods of theoretical analysis,field measurement and numerical simulation,this paper studies the deformation mechanism of adjacent buildings caused by the excavation of deep foundation pits.Combined with the field monitoring results and simulation calculation results,it analyzes the influence and deformation law of the adjacent pile foundation buildings during the excavation of deep foundation pit,And put forward the prevention measures for the deformation of the building adjacent to the deep foundation pit.The main contents of this paper are as follows:(1)Based on the current research results on the deformation of surrounding soil and adjacent buildings resulting in deep foundation pit excavation,the deformation mechanism of retaining structure and ground settlement during foundation pit excavation is analyzed,and it is clear that the principal reason of the deformation of adjacent buildings are lead to the deformation of envelope structure of foundation pit and the displacement of surrounding ground soil.(2)Based on the actual project,the whole process of deep foundation pit excavation is monitored in real time,through the arrangement of monitoring data,the horizontal displacement of the diaphragm wall,the settlement change curve of the surrounding surface and the building during the excavation process are obtained,the change characteristics of the foundation pit itself and the surrounding surface caused by the excavation of the foundation pit are revealed,and the settlement change law of the building during the excavation of the foundation pit is preliminarily obtained.(3)Based on MIDAS-GTS,a three dimensional analysis model of foundation pit and adjacent buildings is built to study the deformation response of retaining structure,soil outside the pit,building and its pile foundation under different excavation depth of deep foundation pit.The law of horizontal displacement and surface settlement of retaining structure,especially the law of building deformation,pile foundation lateral displacement and bending moment change,is obtained Compared with the field measurement results,the measured value is slightly larger than the simulated value,and the simulation analysis is reliable.(4)The prevention and control measures for the deformation of the buildings adjacent are analyzed.Based on the original model,the paper further discusses the control of the deformation of the building by controlling the deformation of the deep foundation pit itself and strengthening the soil outside the pit.Compared with the improvement of the concrete strength of the diaphragm wall,the limit effect of the increase of the support stiffness on the deformation of the building is more obvious;the reinforcement effect of the adjacent buildings under different reinforcement width conditions is obtained,and the appropriate reinforcement width under this condition is determined;it provides some reference for the study of the deformation control of the adjacent buildings of the deep foundation pit in the future.