The Study On Temperature Distribution In Highway Tunnel Under Fire Cases

With the development of the traffic facilities construction, China has become the countryof the largest scale and the longest mileage of highway tunnel in the world, but the comingproblem is the rise of the tunnel fire frequency and the expansion of disaster scale, so theresearch of the tunnel fire is imminent. This paper takes New Qidaoliang Tunnel Fire as theobject of study, by means of the model test and the numerical simulation make a detailanalysis of the distribution law of temperature field in the tunnel space and the lining after thefire.The model test using the scale of1:2.7, and researching the temperature propagation ofthe lining section when tunnel fire with the difference of the moisture content of the liningconcrete; Using the CFD software build a network model, as far as possible to consider theactual fire scale and boundary conditions, etc, simulating the temperature field distributionlaw in the tunnel and in the lining with the difference of ventilation speed in the tunnel, andanalyses the escape method and rescue strategy.Through the model test and the numerical simulation analysis, we can draw thefollowing conclusions:1. The temperature of the longitudinal arch of the tunnel internal space is the highest, thetemperature of the tunnel space near the fire source distribution for O glyph, and thetemperature distance from the fire source distribution for convex glyph; People escape fromthe tunnel center as much as possible, and reduce the height to escape, rescue work start fromupstream of the fire source and try to increase the wind speed, reduce the influence of smokebackflow;2. The temperature of the vault lining is the highest, the second is the hance, and thesidewall is the lowest; the distance from the fire is nearer, the lining is affected by the fire ismore serious;3. The lining inner surface need about10minutes to reach the highest temperature,andthe maintain time related to the source of the fuel and oxygen supply,the cooling rate of theconcrete is slower, it need a long time to reduce to the natural temperature, and the time ismore than30hours; lining is lower, the heating rate is slower; 4.The inner surface of the tunnel lining affected by the fire,the greater of the wind speed,the greater range of influence, the greater range of influence mainly mild damage, moderateinjury and severe damage range is less affected by wind speed; the lining thickness directiondamage reduced with the increase of the wind speed;5. The water content of the lining significant affect on the highest temperature and theheating rate of the lining, the water content is more higher, the highest temperature of thelining is lower, the heating rate is slower; when the difference of the temperature is not big inthe concrete, the moisture content, the greater damage.The study has show that the result of this paper accord with the actual tunnel firesituation. The research method and the theory of this paper provide the basis for simulationwork of the tunnel fire, and provide reference for the tunnel fire protection design.