Analysis Of Influence Of Subway Deep Foundation Pit Construction On Adjacent Buildings

In recent years,the rapid development of urban subway has also brought a lot of deep foundation pit engineering.It's a problem that often needs to be faced that how to ensure the smooth construction of the foundation pit and the safety of the building near the foundation pit in the process of deep foundation pit excavation,the vertical displacement and horizontal displacement will occur in the surrounding soil during excavation,the adjacent buildings will produce deformation when the displacement reaches a certain extent,and take a impact on building function and comfort output,it will lead to destruction of building structure in serious circumstances.Therefore,it has become the difficult and difficult point that how to reduce the structure of the enclosure,the surrounding environment and the deformation near the building caused by the deep foundation pit construction in the process of subway construction.This paper studies the influence of deep foundation pit construction on the adjacent buildings combing with the Shenyang Metro Line 10 Beidaying Street Station Deep Excavation of deep foundation pit construction.This paper mainly analyzes the settlement of the adjacent buildings and the deformation law of the retaining structure of the foundation pit,to assess the safety and stability of deep excavation and building,and put forward the corresponding protection measures during the construction of deep foundation pit.The main research work of this paper is as follows:(1)Combined with the characteristics of deep foundation pit enclosure system and the deformation mechanism of deep foundation pit excavation,the related theories on the influence of deep foundation pit excavation on adjacent buildings are introduced.(2)Summarize the construction process of deep foundation pit retaining structure deformation,ground settlement and building settlement changes through field monitoring.Set up a model of foundation pit,soil and building outside the pit by using the MIDAS/GTS software of geotechnical finite element,and verify the applicability of the model by comparing the calculated values with the measured values.(3)Simulate deformation of retaining structure and surrounding buildings in different influence factors(the distance between the building and the foundation pit,the depth of the foundation pit,the stiffness of the supporting pile,the prestress force of the steel support and the stiffness of the steel support)by changing the working condition and related design parameters of the model.Comparative Analysis:building and foundation pit edge distance is 6m;pre axial force of 60%steel design value,supporting wall thickness is 18mm,diameter 630mm,steel support pile is 1.5 times of excavation depth,pile diameter,pile spacing of 1.1m 1.1m to limit the surrounding settlement the structural deformation and building good effect.(4)According to the adverse effects of deep foundation construction on the adjacent buildings,this paper simulates and analyses the protection measures(optimization of construction scheme of pile design,construction design,steel support pit plus the partition walls)of three kinds of buildings,study the control effect of various engineering measures on the horizontal displacement of the enclosure structure and the settlement of adjacent buildings.The results show that all kinds of measures play a positive role in reducing the deformation of the retaining structure and the settlement of the building.The control effect of the partition wall and grouting reinforcement is more obvious.In the actual project,the economic and safety protection measures should be made according to the construction needs of the site.