Experimental research on temperature field and structure performance under different lining water contents in road tunnel fire

An important feature for distinguishing tunnel lining structure and structure on the ground is the obvious difference of water content. In order to realize the difference between lining structure temperature characteristic and damage which are caused by different water content, a large-scale model test is carried out in this paper through studying the fire entity engineering in Xinqidaoliang to research the temperature field distribution and damage of road tunnel lining structure under different water content. The result shows that the heating rate and the highest temperature of lining internal surface are closely related to the distance to fire and water content of lining. The farther away from the fire, the slower the heating rate is and the lower the highest temperature becomes; for the sections that are equidistant from the fire, the higher the water content is, the slower the heating rate becomes and the lower the highest temperature on lining surface is. As it is closer to the inner of lining, the time needed to reach the highest temperature increases multiply; for the sections that are equidistant from the fire, the higher the water content is, the lower the highest temperature becomes and the longer the time needed to reach the highest temperature is. Due to the water evaporation inside lining structure, there is a stagnation period on the temperature rising curve. The time of stagnation is relevant to water content of lining, the distance from fire sections and the surface depth. When each part of lining structure is equidistant from the fire, the higher the water content is and the lower the temperature of each part is. Besides, for the lining structure with higher water content, the reduced temperature gradient along the lining thickness is apparently higher, as compared with the one with lower water content. The concrete damage of the tunnel lining structure with higher water content is apparently more serious than the one with lower water content. Though the moisture can reduce the temperature inside the lining, the damage of lining is exacerbated. This research can provide reference for further similar projects. (C) 2014 Elsevier Ltd. All rights reserved.