Study on the Stiffness Efficiency and Bending Moment Transferring Coefficient of the Hexagonal Tunnel

The hexagonal tunnel has the advantages of better deformation and mechanical performance, and the space utilization ratio is better than that of the circular tunnel. But it’s still a lack of research on the performance comparison and corresponding design parameters under different types of assembly forms. In order to explorer the performances of the transverse effective rigidity ratio of the hexagonal tunnel, stagger-jointed, straight-jointed and uniform models are investigated based on model tests and similarity theories. The experiment results are verified by numerical simulation. On this basis, numerical models are used to further study the bending moment distribution of the three models, and the bending moment transferring coefficient of stagger-jointed structure is calculated. The results show that: The transverse effective rigidity ratio is between 0.85 and 0.89 under stagger-jointed condition, and significantly better than that between 0.62 and 0.68 under straight-jointed condition. The bending moment distribution and bending moment transferring coefficient of staggered joint structure change periodically. The bending moment transferring coefficient is between 0.18 and 0.36. The results can be used as a reference for the design of hexagonal tunnel.