Abstract: To intuitively understand the effect of shield tunnel backfill grouting pressure on the soil deformation and thus to control the ground surface deformation, numerical simulation was carried out by FLAC^3D on the construction process of a river-crossing tunnel in Shanghai, and  the effect of grouting pressure on tunnel segment floating was analyzed. It's concluded that the soil disturbance varies largely under different grouting pressures and pressure distributions. The tunnel segments exhibits a trend of floating after the grouting slurry were hardened. Ground surface deformation could be effectively controlled when the grouting pressure is between 0.2-0.3MPa. The floating of tunnel segments is affected by the weight of itself, the depth of overburden soil, and the grouting pressure and pressure distribution. The research provides reference for the numerical simulation and construction of shield tunnels.             

Key words: tunnel, grouting, soil, numerical simulation, FLAC^3D