Nonlinear static behavior analysis of single/double-layer frame tunnels with mortise and tenon joint

Prefabricated tunnels are composed of prefabricated components through joints, and the joints are of weaker stiffness than other parts. The static behavior of a tunnel shows nonlinear characteristics. This study analyzes the nonlinear static behavior of single/double-layer frame tunnels with mortise and tenon joint. The mechanical properties of mortise and tenon joint are studied by large-scale model tests. A finite element model of a prefabricated frame tunnel is established, the nonlinear static behavior of prefabricated frame single/double-layer tunnels is studied, and the mechanical properties of a prefabricated joint tunnel and a wet joint tunnel are compared and discussed. The results show that the deflection and opening values of the mortise and tenon joint show a three-stage nonlinear change during the compression bending process. The single/double-layer tunnels with mortise and tenon joint exhibit a stiffness recovery phenomenon under a static load. The deformation characteristics of the single/double-layer tunnels show obvious differences due to their different structural forms. Overall, the anti-deformation capability of the prefabricated frame tunnel with mortise and tenon joint is weaker than that with the wet joint. The structural integrity and stability of the prefabricated tunnel are worse than those of the wet joint tunnel, and its stiffness changes greatly.