The damage mode and forced response characteristics of articulated lining structure: A case study of metro tunnel under a reverse fault action

Abstract

With the continuous development of underground tunnel engineering, there have been a large number of engineering cases of tunnels crossing active faults, and the dislocation of active faults must have a greater impact on the structural safety of tunnels. Therefore, it is of great significance to study the stress characteristics and anti-dislocation design of tunnels crossing active faults. Based on the tunnel of Urumqi Metro Line 1 crossing the Wanyaogou reverse fault, a large-scale physical model test of shear dislocation of subway tunnel crossing the reverse fault is designed and carried out, and the mechanical behavior difference between conventional tunnel structure and articulated tunnel structure is compared and analyzed. The surface displacement, structural deformation, additional earth pressure, strain distribution, fracture distribution and other test results were monitored and recorded, and the forced response characteristics and failure mode of subway tunnel structure under the effect of stick–slip of reverse fault were studied in depth. The results show that the failure modes of conventional tunnel are mainly shear failure at the fault plane, while articulated tunnel is mainly large eccentric failure. Compared with the conventional tunnel, the deformation failure range, strain peak and total crack length of the articulated tunnel are obviously reduced. Besides, there is no spalling phenomenon similar to conventional tunnel. The structure still has a certain residual bearing capacity, that is, the articulated tunnel structure is more adaptable to the forced displacement of the fault, the stress state is better, and its rupture resistance is better. To sum up, the model test study reveals the forced response characteristics and rupture resistance of articulated tunnel structure under reverse fault conditions, which has guiding significance for similar tunnel engineering problems.