Analysis Of Stratum Deformation Rules Induced By The Construction Of Double-Tube Parallel Shield Tunnels For Metro

The shield construction method for its advantages occupies an irreplaceable position in numerous metro construction methods.The impact on the surrounding environment will be inevitably produced in the process of construction.The surface subsidence and strata movement regularity of shield tunnel is one of the most concerned problems in the design and construction.Therefore,the study of the formation of deformation law induced by the subway shield construction is very urgent.With the section of Northern song station to Tangu station of No.1 line of Shijiazhuang metro as the engineering background,the numerical model of double-tube parallel shield tunnels for metro was established by F FLAC3D.The deformation of the soil around the subway shield double tunnel and the stress and deformation of the segment lining structure were studied.And the simulated results were compared with in-situ values.The main achievements are as follows:(1)Strata subsidence appeared normal distribution in the transverse section.The soil layers above tunnel are closer to the axis of tunnel,the vertical deformation caused by shield construction is smaller,the width of ground settlement trough is smaller.(2)The rate of surface subsidence is large in the early stages of the tunnel excavation.The surface subsidence keeps stable gradually with the shield away from the tunnel face monitoring points.The location of the rear shield tunnel excavation face is about 36 m.(3)Close double tunnel leading to soil shield tunneling has mutual disturbance,the formation of the closer it gets to the tunnel axis,vertical deformation curve of asymmetric"bimodal" characteristics of the present,the more obvious.(4)The surface settlement trough width coefficient of Shi Jia Zhuang shield tunnel is 8.56 m,the width of the settling tank parameter is 0.48.The formation volume loss rate was 0.39%.(5)The shield lining segments mainly bears compressive stress in middle location,and bears a little tensile stress in left and right sides.The transverse deformation is given priority to with the ovalization.As a result of the left line tunnel construction disturbance,makes the first installation of the right line of lining segment of the maximum compressive stress increases 14.56%,the largest tensile stress increases 0.12%,the biggest deformation increases by 28.73%.This article research results provides the certain reference value for similar subway shield tunnel engineering design and construction.