Research On Damage Evaluation And Prevention & Control Of Fire Hazard In Long-span And Extra-long Highway Tunnel

With increased construction of long-span and extra-long highway tunnel, the research on damage evaluation and prevention & control of fire hazard in tunnel is becoming increasingly important. Through analysis of causes of fire in tunnels and of calamity prevention facility criterion in home and abroad, this paper made a discussion of fire prevention methods for long and large highway tunnels. And in conbination with the engineering characteristics of the planned 7.6-kilometer-long Xuefeng Mountain Highway Tunnel on Shaoyang to Huaihua Expressway, this paper proposed the design standard of calamity prevention for this tunnel. And then, through deep analysis and research of large quantities of tunnel lining materials and testing data of fire loss on members, it draws a series of change law of the damage degree of the tunnel lining under high temperature, such as burns, crisp, peeling, varied with different burning temperature and time, and that of the compression strength and the tensile strength varied with burning temperature and time. Finally, through deep analysis of damage condition of the tunnel lining under various temperature degree and combining the tests and existing engineering experience, it proposed a simple and practical criterion for categorizing the damage degree of the tunnel structure after the fire hazard, as well as the limit fire resistance temperature of the tunnel structure.Besides, this paper discusses the methods of reliability evaluation of bearing capacity of lining structure after the fire hazard occurred in highway tunnel by adopting compound parallel and series system in reliability theory, evaluates the ineffectiveness probability and its remaining bearing capacity of lining structure under different temperature field of fire hazard on the basis of the probability distribution statistics for the related experimental testing data, provides the reliability index of lining structure, and then gives the applied project examples in Xuefeng Mountain Tunnel.The main study results and conclusions draw from this paper takes into consideration of the real damage of tunnel lining under different fire hazard, various temperature and time. Therefore, it has relatively high and practical value to operate and can provide inference for calamity prevention design for Xuefeng Moutain Tunnel and the similar engineering projects alike.