With the increasing degree of assembly in prefabricated utility tunnels, their structural mechanical performance has diverged from that of cast-in-place counterparts. The connection joints of prefabricated assembled utility tunnels have become structural weak points, where the reliability of connection performance significantly impacts operational safety. To investigate the seismic performance of groove-type prefabricated utility tunnel joints with straight-bolt connections, L-shaped tunnel joints with different bolt diameters and quantities were designed and subjected to quasi-static tests. Experimental results revealed that the typical failure manifested as crushing failure of the concrete in the spliced joint region, with radial crack systems forming at the bolt connection areas of the inner walls, outer walls, and side walls. Additionally, the concrete surrounding the bolt holes exhibited significant compressive damage due to localized stress concentrations. Increasing bolt diameters and quantities enhanced joint ductility coefficients by 27.4%-37.5%, with enhanced bolt constraint effectively delaying concrete crushing progression. Joint stiffness degradation rates decreased by 18%-22%, while energy dissipation values increased by 11.48%-31.06%, demonstrating favorable seismic performance. Based on experimental findings, a joint model was established for mechanical performance analysis, accompanied by a proposed methodology for determining joint mechanical states and a simplified calculation method for ultimate bearing capacity of tunnel joints. Finite element simulations validated the accuracy of the method and confirmed structural safety under extreme conditions. The research outcomes provide theoretical foundations for the study and application of groove-type prefabricated assembled utility tunnels.
