Design and application of a prefabricated structure for large-span arch open-cut highway tunnels

To enhance construction efficiency, improve lining quality, and reduce project costs, this study proposes a prefabricated arch structure scheme for large-span open-cut highway tunnels, specifically targeting the ongoing construction of an eight-lane open-cut tunnel on Chongqing's Xinsen Avenue. By establishing a finite element "load-structure" integrated calculation model and adopting an iterative analysis method, the impact of joint stiffness variations on internal force distribution was determined. Combined with long-term field monitoring and measurements, a thorough analysis was conducted on the performance of the prefabricated arch structure during different construction stages. The results indicate that after assembly into a ring, the structure undergoes a self-adaptive adjustment phase, during which the joints experience significant stress and deformation. Following top-layer backfilling and water level restoration, the axial force on the joints increases, while stress and deformation decrease, exerting a positive effect on the joint bearing capacity. From the construction period to post-opening operations, the stress variation experienced by the joints remains within a controllable range, demonstrating substantial safety margins. This fully validates the safety and reliability of the prefabricated arch structure scheme.