Abstract: Segment cracks during the shielded tunnel excavation have a large impact on the safety and durability of the lining structure. Based on the field investigation for the segment cracking in shielded tunnel excavation of Fuzhou Metro, the numerical simulations for shielded even/eccentric jacking conditions are carried out by using the MIDAS platform. The distribution of the tensile stress with the segment and the segment backend cracking are well analyzed under the unfavorable conditions such as the uneven distribution or the voiding of backend gaskets. Under the even jacking condition, the segment remains in safety even with some unfavorable condition of gasket. Under the eccentric jacking condition, the segment cracking may occur on the backend area where lacking gaskets.

Key words: Subway Tunnel, Shielded Construction, Segment Cracks, Numerical Simulation, Gasket