The Analysis Of Stratum Deformation Caused By The Construction Of Harbin Subway Tunnel With Shallow Tunneling Excavation Method

With the rapid development of national economy, the subway in our countryconstructs very quickly in recent years, at the same time, the shallow tunneling exactionmethod as the main method in subway construction is also used widely. As is wellknown, in the city of densely populated and massed building facilities, duing to soilexcavation disturbing inevitably the surrounding rock and causing the surface to moveand distort, so it will endanger certainly the safety of surrounding ground buildings,urban road and underground pipelines if the surface displacement and deformationexceeds a certain threshold. So studying the stratum deformation law caused by the citysubway tunnel construction with the shallow tunneling exaction method, has the vitalsignificance to reduce the harmful impact of the tunneling excavation on existingbuilding facilities in the city and protect the surface environment.This paper, relying on the Harbin subway tunnel and building the calculationmodel by meaning of large finite element software ANSYS, studies the impact of thesubway construction on surface settlement from four aspects, that is, the excavationmethod, reservation steps length, whether applying the advance support or not and itsconcrete position, and the buried depth of tunnel. The analysis shows that applying theup and down bench and the reserved core soil method, reducing the reserved bench size,applying advanced support in the arch of the tunnel and increasing the buried depth oftunnel can effectively reduce the surface settlement caused by the subway construction.Then this paper simulates the excavation process of the Harbin subway tunnel withthe up and down bench and reserved core soil method, and studies the laws of horizontal convergence, vault settlement, the surface settlement and the deepdisplacement of surrounding rock caused by the subway excavation. According tocollating and arranging the monitoring data of subway construction site, summary andanalyse the horizontal convergence, vault settlement, the surface transverse andlongitudinal settlement law caused by the single hole tunnel construction, and thesurface settlement law caused by double tunnels construction.Finally, through the comparative analysis between the finite element numericalsimulation results and the measured data of construction site, get the strata deformationlaw caused by subway tunnel construction with the shallow tunneling excavationmethod, and put forward the corresponding construction suggestion measures.