Abstract：Shanghai Yangtze Tunnel is the largest diameter and longest once-driving distance shield tunnel in the world until now. The average covering soil is 9.0 m，and the shallowest covering soil is only 6.8 m. In order to control the floating of segment during large diameter shield driving under high water head and shallow covering soil，a single-liquid synchronous grouting process is adopted. The construction process of Shanghai Yangtze Tunnel east line river-crossing part is numerically simulated with a 3D elastoplastic coupled anisotropic seepage and stress model which could consider the soil permeability varying with volumetric strain. Combining with the measured data，the change laws of tunnel segment¢s rising displacement and the pore water pressure outside the segment during tunnelling are revealed；and the pore water pressure distribution outside the segments and above the crown when the deformation has been stable are studied. Moreover the influences of groundwater seepage on surface settlement and segment internal forces under different water depths are analyzed. The results show that the current single-liquid synchronous grouting material and technology can effectively control the floating of segment；the ratio of pore water pressure outside the segment to hydrostatic pressure increases with the depth when the segment deformation has been stable；and the action of groundwater improves the segment¢s forced state；but the negative impaction of high pore water pressure caused by the high water level on the segment force should be paid more attention to.
