| With the rapid development of economy and the progress and innovation of tunnel construction technology in China,highway tunnels are no longer limited to the traditional straight-line short tunnels,but gradually developed into a variety of extra-long tunnels,underwater tunnels and curved tunnels and so on.The world's first highway double-spiral tunnel was built in Yaxi highway of the northern slope of TuoWu Mountain of Li Zipin to Tie Zhaizi,providing successful experience to design and construction of highway tunnel.However,highway tunnelshas the characteristics of high traffic density,a wide range of carrying goods,long lines,less entrances and exits,dim light,strong closure,which resulting high possibility of fire occurrence in road tunnels.Highway tunnel fire generally has characteristics of high fire hazard,high temperature,large amounts of smoke,low concentration of oxygen,great difficulty of evacuation and rescue.Therefore,it is of great practical significance to study the spread characteristics of fire smoke and the emergency rescue work of fire accident.Through access to domestic and foreign literature and engineering research,using research method of theoretical analysis and experiment,by combination of physical experiment and numerical simulation,relying on the key research project of the Ministry of Public Security,a 1: 67 reduced-scale spiral tunnel test model was built and a 1: 67 scaled-down and 1: 1 full-size numerical model was set by CFDto study the smoke spread pattern and related laws of spiral tunnel fire,and forfurther study the rescue technology of spiral tunnel fire emergency.The main contents and results are as follows:(1)According to the theoretical basis of similarity theory,similarity criterion and scale relation,a 1:67 reduced-size spiral tunnel test model was established.The influence of different slope and curvature on smoke spread pattern of spiral tunnel was studied by simulating fire test.Temperature field,velocity field and visibility condition in tunnel fire were analyzed under different slope,curvature parameters and fire size to provide the data reference and theoretical foundation to the real fire test of spiral tunnel.(Chapter 2,Chapter 3)(2)A 1:67 scaled-down tunnel modelwas established by modeling tool ICEM CFD in ANSYS software.The tunnel fire test was conducted in nine different experimental conditions,and the simulation results were compared and analyzed at different slope conditions.The results of longitudinal temperature distribution along tunnel ceiling and 2 m-height,including temperature distribution above the fire source were obtained.The results of numerical simulation and scaled-downexperiment were compared and analyzed,which shows a certain similarity of both results in the longitudinal temperature distribution pattern.The smoke spread pattern under the synergistic effect ofgradient and curvature of spiral tunnel were discussed,and the feasibility of establishing a spiral tunnel entity model by CFD was verified at first time.(Chapter Four)(3)A 1:1 full-size spiral tunnel model with 0.2 m × 0.2m grid size,1/125 curvature and 950 m length was established,andparameters like different tunnel slope(1%,3%,5%,7%),4 different site of fire source and different fire size(20MW,30 MW,50MW)were set.20 full-size fire tests under different experimental conditions were conducted,and the simulation test results under different slope,different fire size and different curvature of tunnel were compared and analyzed.The changeable rule of temperature field,velocity field,smoke concentration and visibility condition of the spiral tunnel were studied,which provide the theoretical basis and engineering parameters for smoke control in the process of the design and operation ofspiral tunnel.(Chapter Five)(4)According to different characteristics of the spiral tunnel fire,the comprehensive research on the emergency rescue technology of the spiral tunnel fire accident was firstly carried out,and the scheme of the emergency rescue technology for spiral tunnel fire accident was formulated.The specific objectives of fire emergency plan in highway spiral road tunnel,the work targets and principles of tunnel emergency rescue,the facilities and action program of emergency rescue and the after-fire disposal plan of spiral road tunnel were confirmed.(Chapter Six)This paper provides theoretical basis and data support for the study of the development law of spiral tunnel fire and the smoke spread pattern.It is helpful for constructing scientific and reasonable emergency rescue system of spiral tunnel,which provides theoretical basis and has great practical significance on reducingtheoccurrence of large accidents during the operation of spiral tunnel and solve the key issues during the construction and operation of highway tunnel. |
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