Study On Construction Technology Of Deep Foundation Pit Proximity

With the development of economic construction,the demand for urban supporting facilities is becoming more and more abundant.The development and use of urban land is also more frequent,and urban excavation projects have become more and more visible.The construction of deep foundation pits has a serious impact on public property and the environment.The disturbance to the surrounding environment should be minimized.Once an accident occurs,it will inevitably lead to land subsidence,cracking of underground pipelines,and cracking and tilting of adjacent buildings.It has caused great adverse effects and losses on residents’ lives and society.Therefore,the research on the influence of excavation on the surrounding environment and adjacent buildings has become an important topic today.Based on the deep excavation project of Jiefangbei Xinhua Bookstore,the paper establishes a relative positional relationship model between excavation of foundation pits and subway tunnels and buildings through theoretical analysis,three-dimensional numerical simulation and engineering monitoring.The spatial effects under different excavation methods have analyzed and verified the influence of adjacent subway tunnels and buildings,and reasonable suggestions have been put forward.The main research work done in this paper is as follows:(1)The ground settlement caused by excavation of the foundation pit,the uplift deformation of the bottom of the pit,and the influence on the adjacent subway tunnel were discussed.The reasons for the impact were analyzed.Discuss the effect of pile anchor structure to control the deformation of pile top.(2)The formation mechanism of soil arches and rock arches was analyzed.The spatial effect coefficients of excavation of deep foundation pits were deduced,and the method of determining the reasonable pile spacings was discussed.According to the theory of purely bending elastic beams,a method based on the tensile strength of rock masses was proposed.Arch equation.(3)Using numerical simulation,the arch strength rules under different excavation methods and supporting forms such as layered excavation for deep foundation pits,excavation from excavation,island excavation,etc.were compared,and the surface,adjacent tunnels,and foundations in the affected area were analyzed.The law of the bottom of the pit and the change of the supporting structure is proposed,and areasonable excavation method,the spacing of anti-sliding pile supporting and the arrangement of the monitoring section are proposed.(4)Using Flac3d to simulate the block and layered excavation of the deep excavation of Xinhua Bookstore Fashion Culture City project,and analyze the construction responses of the pile-anchor support structure,the bottom uplift and the land subsidence,and combine the monitoring data with the tunnel.The deformation was compared and analyzed.