Research On The Deformation Caused By Annular Inner Support Deep Excavation And The Influence On Existing Building

In recent years,with the rapid development of the city,a large number of deep foundation pit projects have been occurred.In the process of developing and using urban land,foundation pit engineering usually appears in the area where engineering environment is much complex.Because the engineering environment has strict requirements for the deformation,it is necessary to carry out the study of deformation characteristics caused by excavation.Based on the engineering background of the Sino 2B Project,this paper studies the deformation caused by the excavation of the annular inner support deep foundation pit and its influence on the existing buildings,the main contents and results are as follows:(1)The horizontal deformation characteristics of the retaining structure,the deformation characteristics of the ground surface and the deformation characteristics of the surrounding buildings caused by the excavation of the annular inner support foundation pit are studied.Under the effect of three annular inner support,the horizontal deformation form of the retaining structure is parabolic type,the deformation form of the ground surface is mainly concave groove type;The settlement of the surrounding buildings manifests as differential settlement,and its horizontal movement develops toward foundation pit directly.(2)The displacement characteristics of the surrounding soil caused by the excavation of the annular inner support foundation pit are studied.The influence range of the surrounding soil in the depth range caused by the excavation is triangular distribution form,the influence range is the largest at the ground surface,it decreases gradually with the depth increasing,and tends to 0 at the bottom of the retaining structure.(3)The influences of the support position of the annular inner support structure on the horizontal deformation characteristics of the retaining structure,the deformation characteristics of the ground surface and the deformation characteristics of the surrounding buildings are studied.When the first annular inner support structure is close to the surface,the displacement at the top of the retaining structure becomes small,the settlement of the surface near the foundation pit becomes small,the deformation of the nearby building becomes small.(4)The deformation of the nearby building caused by excavation is studied in terms of the location of building and embedded depth of foundation.For the foundation pit engineering near the existing building,when the height difference of the bottom of the existing building foundation with the bottom of the foundation pit to the distance of the existing building with the foundation pit radio(?H/d)satisfies certain condition,it can be considered that excavation will not affect the nearby buildings,for the foundation pit project that is similar to this paper,when ?H/d is less than 0.4?0.6,it can be considered that excavation will not affect nearby buildings.