Research On The Impact Of Tunnel Shield On The Stratum Subsidence And Adjacent Buiding

Tianjin is a typical soft soil area， shield tunnel method is widely used in thesubway tunnel construction in Tianjin. The impact on Stratum Settlement andadjacent buildings and its foundation which caused by the tunnel shield is alsowidespread concerned. In this paper,the impact of tunnel shield on the stratumsubsidence and adjacent surface buiding is the research object, the initial introductionof the tunnel-the foundation-the upper structure interaction concept. through theindoor model test and numerical simulation analysis with the background of TianjinMetro Line2for aims to provide a theoretical basis for the impact of the surroundingstrata and structures tunnel shield Construction for of Tianjin subway tunnel shieldconstruction and other soft soil area cities. By comparative analysis of model testsand numerical simulation, the following main conclusions:(1) curve on the surface lateral distribution approximates a normal distributioncurve, tunnel centerline axis of symmetry symmetric distribution.(Equivalent to theend of10days after the actual shield) in the64hours after the end of the tunnel shieldsoil subsidence trend does not change. The closer from the tunnel shield StratumSettlement of the more obvious, the equivalent of three times away from theexcavation depth beyond basic stratum subsidence from Shield Construction, and thepresence of the building had an impact on surface subsidence.(2) the tunnel shield cause soil displacement thus resulting in close to the surfacebuilding overall uneven settlement and horizontal displacement occurs, the testsshowed that the relative position of the shield tunnels in the moment and shield thesurface of the building the building overall deformation The impact shield5h and20hwhen that shield the boring start time building deformation more severe. Along thetunneling direction, the building space displacement is more complex, but thebuilding as a whole is biased tunnel side.(3) shield tunnel excavation, pile foundation settlement down to the main subjectto the pull-down stress, the the shield gap during pile foundation by upwardcompressive stress. Shield the process of strain increment is the first positive and thenegative increase leveled off, and then again a positive increasing trend Shield5h and20h pile strain changes on the basis of more dramatic, shield excavation moment onpile foundation. The closer from the tunnel axis, the greater the change of pilefoundation horizontal displacement and stress-strain than both sides of the central pilefoundation settlement large, and the pile foundation at the bottom than the upper handshield.(4) tunnel shield tunneling framework of beams and columns, the main subjectduring the Rally, the tunnel shield intermittent framework of beams and columns bythe main tensile stress-strain curve to negative incremental. Point in time strainmutation occurs shield excavation moment5h and20h. Nearer the more obviouschanges in the framework of beams and columns deformation and stress away fromthe tunnel axis. The shield tunneling direction by stratum subsidence and stratigraphic level and curvature deformation, stress and strain of longitudinal frame beams andcolumns change is more complex, there is no uniform law.