Experimental study on reinforcement method with channel steel for corrosion tunnel lining structure

Under the influence of the erosive stratum environment, the tunnel lining concrete generally experiences the deterioration of concrete corrosion and the loss of strength during its long service, which seriously endangers the stability of tunnel lining structure and the safety of driving. This paper presented a repair scheme utilizing the channel steel reinforcement method for addressing large-scale corrosion of tunnel lining structure.An indoor component test was conducted to assess the section force characteristics of the reinforced and repaired tunnel lining components. The results indicate that the axial strain of the section in the column specimen basically follows a linear distribution, which can meet the assumption of flat section. When the specimens reached the ultimate load, the concrete on the edge of the tensile zone showed tensile cracking failure characteristics. The tensile stress on the tensile side was provided by concrete and channel steel, while the concrete on the compressive side showed brittle collapse failure. According to the mechanical characteristics of the section, the bearing capacity of the reinforced specimens was divided into the ultimate bearing capacity of cracking resistance and the ultimate bearing capacity of failure, and the calculation method of the bearing capacity of the channel reinforcement method was derived. On this basis, a numerical analysis model was established, and the results were compared with the experimental test and theoretical simplification methods. The results demonstrate close agreement among the three methods, with a maximum deviation is less than 8%, which indicates that the established method for calculating the bearing capacity of corroded components after reinforcement is reliable and can be used for the design calculation of corroded lining reinforcement. Finally, a restoration scheme is proposed for sections with a corrosion depth of engineering lining concrete less than or equal to 10 cm. The specific scheme is to chisel away the old concrete with a thickness of 10 cm on the lining surface, bury 18#B channel steel with 1m longitudinal spacing, connect and fix it with the existing lining structure through expansion bolts, and backfill C30 micro expansion concrete. After strengthening according to the above scheme, the section safety factor of lining is 3.6, which can ensure the safety and stability of the lining structure. © 2023, Central South University Press. All rights reserved.