Time-dependent performance assessment of mountain tunnels considering the hazards associated with squeezing soft rock and nonuniform steel corrosion in RC lining structure.

Mountain tunnels buried in squeezing soft rock inevitably undergo a rapid degradation with time due to creep behaviors of surrounding rock. The performance of tunnel would become more exacerbated when steel corrosion occurs in lining structures. High failure risk of tunnel lining within a short time after construction would significantly shorten its service life. Since the properties of rock mass in space and the corrosion of reinforcements in space–time exhibit a high uncertainty in practices, it is necessary to perform a reliable performance assessment of tunnels by incorporating the concept of random field-based reliability analysis. In this study, a novel approach for reliability assessment of mountain tunnels under the hazards associated with creep behavior and non-uniform steel corrosion is presented. A creep constitutive model of rock is introduced firstly; Random field-based modeling for the spatial-variant properties of rock mass is proposed; and a spatio-temporal approach for describing the spatial variability and stochastic process of steel corrosion is established. Numerical simulation for the deteriorated mountain tunnel is implemented by integrating the FLAC3D with MATLAB. In an illustrative example, both deterministic and probabilistic analysis on structural performance were conducted. The time-dependent deformation, axial forces and bending moments of lining structure are investigated. [ABSTRACT FROM AUTHOR]