Application Analysis on Convergence Deformation of Soft Soil Shield Tunnel Controlled by Grouting

At present, the measure to control the large deformation of the tunnel's transverse diameter convergence is to adopt the grouting from the outside of the tunnel, but the direct control effect is still taken as the standard in the implementation process, so there are still many deficiencies in the understanding of grouting to control the tunnel's convergence deformation in engineering practice. Firstly, the influence range of grouting diffusion is analyzed based on the cavity expansion theory, and the diffusion pattern of grout and the change of excess pore pressure caused by grouting are verified by in-situ tests; Finally, the influence of grouting is simulated by volumetric strains method. The results show that the diffusion of grouting compacted soil is obvious in the clay layer in Shanghai, and the radius of plastic zone affected by grouting is about 8 ~ 9 times of the diffusion radius of grout; The grout diffusion radius of 1.5m grouting scheme is within 30.0cm; Cement soil is formed in the grouting area, and the strength is increased and the compressibility is decreased; More than half of the excess pore pressure dissipated 1h after grouting; The simulation results show that the convergence deformation of tunnel transverse diameter is about −1.0 ~ −2.0mm by single hole grouting.