Detailed damage mechanism of deformed shield tunnel linings reinforced by steel plates

To ascertain the variance in the detailed damage characteristics of tunnels reinforced at different deformation degrees with steel plates, a refined finite element (FE) model of a stagger-jointed shield tunnel was established, and an FE approach to simulate the bond behaviour between steel plates and linings was proposed. After the rationality of the FE analysis was verified with a refined physical model test on the steel-plate-reinforced tunnel, a series of FE simulations were performed to investigate the influence of the existing deformation on the detailed damage mechanism of the post-reinforcing lining. The results show that the bond damage occurring near the crown is mainly caused by the combination of tension and shear and has high brittleness, whereas the bond damage occurring near the waist is mainly caused by shear and has high ductility. A decrease in the existing structural deformation before reinforcement improves the effectiveness of steel plate reinforcement, as manifested by less bond damage near the crown, a better co-bearing effect between steel plates and segments, and a greater improvement in the flexural stiffness of the joints near the waists. To guarantee the effectiveness of the steel plate reinforcement on the deformed tunnel, it is reasonable to set the upper limit of the structural deformation before reinforcement at 15.0% of the outer diameter of the segmental ring.

Automated summary

A refined finite element (FE) model of a stagger-jointed shield tunnel was established to examine the variation in damage characteristics of tunnels reinforced at different deformation degrees with steel plates. The bond behaviour between steel plates and linings was simulated using an FE approach. The study found that a decrease in existing deformation improved the effectiveness of steel plate reinforcement, with less bond damage near the crown, a better co-bearing effect between steel plates and segments, and a greater improvement in flexural stiffness near the waists.