Study On Construction Disturbance Control Technology Of Deep Foundation Pit Taken A New Deep Foundation Pit Project In Qingyuan

In recent years,with the increasing construction of infrastructure such as high-rise buildings,rail transit,and urban underground space in China,research on construction control,disturbance effects,and stability of deep foundation pits has gradually become a new hot spot in geotechnical engineering.The relevant engineering examples have shown that it is necessary to clearly define the disturbance reason,perform disturbance control,and reduce the impact on the surrounding environment during the construction of deep foundation pits.In this paper,based on a new deep foundation pit project in Qingyuan,on the basis of on-site monitoring data,combined with numerical analysis methods,the reason and control measures of the deep foundation pit disturbance effect were studied.The main research results are as follows:(1)On the basis of literature investigation on disturbance reason of foundation pit excavation,the causes of lateral deformation of retaining structure,surface settlement outside pit and disturbance of foundation pit uplift inside pit are analyzed.(2)Based on summarizing the technical points of the conventional monitoring project of the foundation pit and extracting the monitoring data of a deep foundation pit project,it is concluded that the depth and depth of the foundation pit excavation determines the lateral deformation of the building envelope;The axial force growth rate is fast,and the fluctuation amplitude of the concrete support axial force is stable;the ground surface settlement rate around the foundation pit is mainly related to the close cooperation between excavation and support erection.(3)Based on the establishment of the calculation model for the deep foundation pit excavation disturbance effect,it is concluded that there is little difference in the vertical deformation along the depth direction of the enclosing structure of the same section;the supporting axial force varies with the deepening of the excavation depth.Large,after the excavation is completed,the axial force of each supporting shaft reaches a maximum value;the surface settlement of each excavation stage has a “concave” shape,and the surface settlement on the outside of the long side is greater than the surface settlement on the outside of the short side;the uplift of the bottom of the excavation presents a typical “ Thedeformation pattern in the middle and sides is small;the analysis of the monitoring projects all show a clear spatial effect.The deformation of the long-side monitoring project of the foundation pit is larger than that of the short-side monitoring project.(4)Based on an in-depth analysis of the reason of excavation disturbance of foundation pits and numerical calculations,the specific construction steps before excavation and excavation are put forward,and concrete disturbance control measures are proposed to ensure the foundation pit structure and subsidiary The monitoring indicators such as structure and ground subsidence are always within the scope of specification and design requirements.(5)Based on the study of disturbance reason of deep foundation pit and the summary of control measures,the disturbance control system of deep foundation pit supporting,monitoring and disturbance is put forward in view of the disturbance during the construction period of deep foundation pit,which provides a useful reference for similar projects in the future.