Damage evolution and safety assessment of tunnel lining subjected to long-duration fire

Tunnel linings would suffer heavy structural damage or even collapse when exposed to a long-duration fire. The damage is greatly affected by heating time. In this paper, a theoretical method is suggested to investigate the thermo-mechanical behaviors of tunnel lining subjected to a long-duration fire loading. A 2D unsteady-state thermo-mechanical model is established to analyze the time-dependent temperature and stresses distributions of tunnel lining under fire. A modified RABT fire curve is employed to describe the tunnel fire development. By using Laplace Transform and series solving method for ordinary differential equations (ODE), the analytical solutions of time-dependent temperature and stresses are obtained and numerically verified. Based on the temperature criterion and the residual stress criterion, damage evolution of tunnel lining is graphically presented and discussed. According to the comparison results, the consistence of these two criteria is theoretically verified.