Study on the mechanical properties of prefabricated assembled cover arch reinforcements in tunnels

The prefabricated assembled cover arch reinforcement method offers rapid construction and high quality, effectively addressing the challenges of cast-in-place cover arch reinforcement used in tunnel linings in mountainous areas of China. This study investigated the mechanical performance of prefabricated assembled arches in tunnels through model tests and numerical simulations. The results indicate that joint opening and deflection, as well as their change rates, increase with eccentric distance. There is a roughly linear relationship between joint opening and deflection with increasing load. At an eccentric distance of + 0.2 m, the peak stress appears on the outside of the joint, with a valley on the inside, and stress concentration at bolt holes. The application of bolt preloading enhances the joint's stress performance. Furthermore, the stiffness of the lining and soil significantly impacts the mechanical response of the cover arch, with peak stress mainly observed at the foot of the cover arch and the handhole of the joint.