Abstract:

Tunnel lining could be damaged by tunnel fire, which may directly or indirectly induces the collapsing of tunnel. If engineers could better understand the distribution of thermoinduced damage, they can either improve the design by considering the protective measures beforehand, or they can provide better repairing plans by predicting the damage zones more accurate after tunnel fire. Previous researches used discrete heat treatment method to prepare the specimens; predictions between data points cannot be accurate. In this research, continued heat treatment method was used to prepare the specimens; the tensile strength and fracture toughness of the heattreated specimens were investigated. Based on test results, a more rational and accurate prediction equation is proposed and the critical damaging temperature is found to be about 540~550 ℃. The test results can be used as reference in engineering design for better protection of tunnel lining against fire. 

Key words: continued heat treatment method, tunnel fire, LogLog method, tensile strength, fracture toughness