Effects On Existent Tunnel Caused By Small Spacing Parallel Shield Tunnel Construction

The increase of the subway construction demand under the background putsforward new requirement to underground space utilization. In order to take use ofunderground space adequately, the distance between the tunnels is more and moreclosely, and small spacing shield tunnel research and therefore is becoming more andmore.In recent years, small spacing shield construction research method basicallydepends on two kinds of method. One is to adopt numerical analysis method, usingthe finite element analysis software to simulate the shield excavation process, and theother is to combine experience and theory, combining with construction monitoringdata analysis and forecasting the deformation of the tunnel.It is written according the engineering project of small spacing shield excavationof Tianjin Metro. The affection of segment lining internal force and displacement,displacement of lining surrounding soil and surface settlement on the nearly spacedtunnel during shield tunneling is analyzed and predicted considering soilconsolidation and creep. The calculation result is compared with the measured data,and proved that the simulation is rational. The preliminary conclusions give thereferences and guidance to the tunnel construction in theory.On this basis, considering the engineering geological condition parameters as thebasis, the influence to the original tunnel caused by small spacing parallel shield afterexcavating is analyzed, and with different tunnel clear distance, different shielddriving jacking force and first built tunnel reinforcement, the different parameters isanalyzed. The sensitive degree of tunnel to the parameters of surrounding soils isdifferent, so in this parameter conditions when excavating, the surface displacement,lining displacement and internal force of the change of lining is analyzed in detail tofind out the degree of parameters influence on the internal force and displacement ofsurrounding soils to the small spacing shield original tunnel. The research canprovides theoretical basis and guidance to small spacing shield tunnel excavation inTianjin.