A Study On Fire Damage To Subway Tunnel Lining And Evaluation Method After Fire Scenarios

The development of metro system solves large capacity traffic problem in big cities effectively. However, large passenger volumes in the metro system will cause tremendous social and economic losses in the event of fire. During the fire, high-temperature will cause thermal expansion of lining structure, while lining material strength and modulus decreased sharply, resulting in structural deformation increased and bearing capacity decreased. How to use proper methods evaluating fire damage to tunnel lining after the fire, is important to planning repair and reinforcement scheme, restoring tunnel function, guaranteeing structure safety, etc.High-temperature damage to tunnel lining and the evaluation methods after the fire are studied in the paper. The contents involve: (1) deterioration of lining concrete and segment of subway shield tunnel after fire scenarios; (2) calculation theory and simplified calculation method of section temperature field of lining; (3) calculation theory and recomputation method of section high-temperature bearing capacity of lining; (4) methods, criterion and procedure of detection and evaluation after subway fire scenarios.Based on the test data, the deterioration regularity of C50 concrete, which is used in subway shield tunnel, is researched. The stress-strain relationship of concrete after high temperature is studied. Through the fire test of one-third scale model segment, the regularity of temperature field of segment section is analyzed. After high temperature, the appearance of segment changes significantly, and the stiffness and bearing capacity also deteriorate. Through proper selection of assumptions and thermotechnical parameters, the software of Marc is used successfully in simulating the transient thermal transmittance process of lining, by verified with test results of model segment. Based on calculation, simplified calculation formula of temperature field of shield tunnel lining is given. The calculation theory of section high-temperature bearing capacity of lining is also discussed in the paper. The principle of integration method, stripping method and equivalent section method is given. The procedure and formula of recomputation in section high-temperature...