Design of assembled bolted joints for secondary lining reinforcement in highway tunnel
Addressing the inefficiencies of on-site welding and binding of secondary lining steel bars inhighway tunnels, along with the challenges in quality control, this study derives a formula for calculat-ing the ultimate bearing capacity of reinforced concrete lining sections based on the linear concrete soft-ening constitutive model and the stress-strain relationship of steel bars. By integrating the ultimate bearing capacity of bolt connection surfaces and taking stress distribution coefficients as control fac-tors, the design method for bolts at connection surfaces is established. This method identifies charac-teristic sections under axial compression, large and small eccentricities, and pure bending states, thereby controlling the ultimate bearing capacity of reinforced concrete sections and bolt connectionsurfaces at these sections. The study applies this design method to select bolts and determine bolt dis-tribution at connection surfaces using parameters of the tunnel site's surrounding rock, cross-section dimensions, and support parameters. Additionally, it provides a segmentation scheme for prefabri-cated steel bar segments and validates the rationality of the assembled bolt joint design for secondary lining steel bars through numerical simulation. Results indicate that prefabricated bolt assembly redis-tributes stress in the two-liner structure, slowing down stress and deformation growth rates to achieve stabilization. Specifically, stress reductions of 58％ at the left arched shoulder and 53％ at the left arch foot are observed, accompanied by varied reductions in displacement. Although stress increases on the bolt connecting surface at the arch's base, the high bearing performance of the bolt reduces uplift, ef-fectively optimizing the structure.
万方数据
维普
