Similar Model Experimental Study on the Mechanical Behavior of Prefabricated Assembled Tunnel Lining Structures

In the rapid process of urban development, prefabricated segmental lining structures have become one of the primary lining forms for super-large section tunnels due to their advantages such as fast construction speed and ease of quality control. This study employs a combination of similar material model tests and numerical simulations to compare and analyze the effects of the" upper prefabrication + cast-in-place back-arch" segmented design and the "three-part blocks" segmented design on the bearing performance of the lining. The results indicate that the failure modes observed in numerical simulations are highly consistent with those in model tests, with significant damage zones appearing at the crown and springing in both cases, thereby validating the accuracy of the numerical model. During the loading process, the crown and springing, as vulnerable points, were the first to crack when the load reached 0.6 Fu. The vertical displacement response curves of the crown obtained from scaled model tests and numerical simulations were highly consistent, with final values stabilizing at 18 mm. The study reveals that when the flexural rigidity of the joints is less than 40 MN·m/rad, the axial forces and bending moments on the lining in the “three-part blocks” design are significantly reduced, while the lateral displacement in the “upper prefabrication + cast-in-place back-arch” design is smaller. This provides important theoretical support and an experimental foundation for subsequent research on the segmented design of full-scale super-large section tunnels.