Abstract: To determine the variation laws of segment dislocation caused by the buoyancy of synchronous grouting slurry during shield tunneling, a method for the calculation of segment dislocation is proposed, starting with an analysis of the integral forced status and ending with the calculation of local deformation, based on a largediameter shield tunnel project. Then, via numerical and comparative analysis, a longitudinal analysis model of the shield tunnel during the construction period and a threedimensional(3D) calculation model of segment dislocation are established to calculate segment dislocation under different cover depths, grout densities, and grout solidification times. The results indicate the following. (1) It is reasonable to use the longitudinal analysis model of the shield tunnel during construction to calculate the longitudinal structural inner forces and then substitute the force boundary conditions into the 3D segment dislocation calculation model to determine the amount of segment dislocation. (2) As the segment ring exits the shield tail, it is subjected to the buoyancy of the grouting liquid and the buoyancy of the surrounding water, resulting in negative bending and maximum shear strain, which is prone to ring dislocation. (3) The segment dislocation laws are as follows: it begins with an upward stagger, followed by a downward stagger after passing through stable segments, and it eventually enters the stable stage. (4) The slurry′s qualities have a considerable impact on the occurrence of dislocation during tunnel construction. Dislocation between rings can be effectively decreased by lowering the density of the slurry and increasing the rate of solidification. (5) As the tunnel cover depth increases, segmental ring dislocation is reduced due to the increase in the overlying stress and the improved surrounding rock properties. As a result, greater attention should be paid to the occurrence of segment dislocation in shield tunnels with a shallow cover depth.

Key words: shield tunnel, segmental lining, synchronous grouting, segment uplift, segment rings dislocation