experimental and numerical study on the bearing behaviour of confined concrete arch for a traffic tunnel

The control of surrounding rock is a challenge faced during large-section tunnel construction, resulting in insufficient strength of the traditional support. confined concrete arches with high strength and rigidity are suitable for controlling large-section tunnel surrounding rocks. to effectively control the soft surrounding rock of large cross-section tunnels, it is necessary to study the bearing characteristics and influencing mechanisms of confined concrete arches. a mechanical test on large-scale arch in traffic tunnels is conducted. the deformation mode and ultimate bearing capacity of the arch are analysed. the test results show that the deformation mode of the confined concrete arch is “the vault and bottom converge inwards, and the whole arch becomes flat”. the maximum bearing capacity of the arch in the stable bearing stage is 830.7 kn, and the ultimate bearing capacity is 1157.2 kn. on the basis of laboratory tests, numerical simulations are conducted on different arch dimensions and cross-section parameters. the influence mechanisms of the section dimension and arch design parameters on the bearing capacity are clarified. as the section dimension increases, the load-bearing capacity of the arch decreases continuously. the ultimate bearing capacity of the arch with an on-site size is 784.5 kn, which is 32.2% lower than that of the arch in the laboratory test. a comprehensive evaluation index considering cost and bearing capacity has been established to select reasonable design parameters for confined concrete arches. based on the above research results, engineering suggestions are put forwards, and the arch is applied in the letuan tunnel, which effectively controls surrounding rocks. © the author(s), under exclusive licence to the iran university of science and technology 2023.