RC SEGMENT MODEL EXPERIMENT ON THE BEHAVIOR OF TBM SHIELD TUNNEL LINING UNDER HIGH TEMPERATURE IN FIRE

Abstract

The fire resisting performance of shield tunnel without secondary lining is examined. Fire tests under RABT curve are executed by using the full-scale RC segment specimen. The characteristics of the spalling are affected by the stress conditions of the concrete. Therefore, the design load for the crown (sagging moment) or spring line (hogging moment) of actual tunnel is introduced into the specimen.
It pays much attention to detect explosive spalling and thermal deformation behavior of the specimen during the test. The thermal deformation of the sagging specimen with insulation is small and the damage is hardly caused in the concrete surface.
Severe explosive spalling occurs in the hogging specimen without insulation. Thermal deformation of the specimen is also very large, even in this case the specimen can maintain the design load and it would not have resulted in collapse of a tunnel. No explosive spalling occurs in the both hogging and sagging specimens with polypropylene fiber. The rebar temperature of the specimens remains low, and the deformation are also relatively small.
It is confirmed that the polypropylene fiber can be expected enough load bearing capacity though its effect is not as pronounced as with the insulation.