Behavior of reinforced concrete and steel fiber reinforced concrete shield TBM tunnel linings exposed to high temperatures

This paper presents comprehensive experimental test results on the behavior of the reinforced concrete (RC) and the steel fiber reinforced concrete (SFRC) shield TBM (Tunnel Boring Machine) tunnel lining segments and the lining rings exposed to a HC (Hydrocarbon) curve. The experimental results indicate that the nonlinear nonuniform temperature distribution within the concrete linings causes significant nonuniform thermal expansion and material property degradation. The initial loads exert significant effects on the behavior of the lining segments, whose performance was remarkably deteriorated in the fire. The coupled thermal–mechanical effects, induced by the nonuniform thermal expansion, the deterioration of material properties and the interaction between adjacent member segments, lead to considerable deformations of the lining rings, dynamic internal force redistribution and reduction of load bearing capacity. The lining joints play a critical role upon the behavior and the failure pattern of the lining rings. Based on our test results, the RC linings perform better than the SFRC linings under intensive tunnel fire. Other notable, new observations and behavior are also presented in this work.