The paper gives the results of a fire development study using physical models of inclined vehicular traffic tunnels scaled 1:60. The tunnel inclination varied within 0-10% with a 2% increment. The fire strength initiated and developed in a natural tunnel varied within 5-15 MW with a 5 MW increment. The length of the natural tunnel was 360 m, width: 8 m, height: 6 m, cross-sectional area: 48 m2, and the tunnel width and height ratio: 1.33. The model of the natural tunnel of the given geometry was made of a 2-mm-thick stainless steel sheet with an appropriate scale. The sizes of the tunnel model are: length: 6 m, width: 0.16 m, height: 0.12 m, and cross-sectional area: 0.0192 m2. By doing experiments on this model, we studied the nature of propagation of gases (smoke) emitted during the fire initiation and development, specified the impact of the gradient factor on the rate of variability of the critical velocity and backlayering distance. The said characteristics were studied according to the air temperature variability in the tunnel model. The air temperature was measured with K-type thermocouples equipped with open and closed detectors. Maximum measuring temperature was 800°C. The thermocouples were installed in the ceiling of the tunnel model along the entire length, with 5 and 10 cm increments. The fire was modeled with natural gas. Ventilation air was supplied into the model by an axial fan from one portal of the model. The velocity of the ventilation air was measured with an anemometer, and the air discharge was calculated at every moment according to the velocity. The required strength of the modeled fire was provided by natural gas, and the measurement was done with a volumetric and mass regulatory meter. Simultaneous data collection, processing, analysis and digital transmission of data from the K-type thermocouples, anemometers and natural gas flow meters were provided with DT-85 Datataker. The obtained results can be used to develop road tunnel ventilation projects that take into account the impact of fires on ventilation.

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საავტომობილო გვირაბების სხვადასხვა მასშტაბის ფიზიკურ მოდელებზე დაგეგმილი გვაქვს ვენტილაციის მნიშვნელოვანი ტექნოლოგიური პარამეტრების შესწავლა ხანძრის პირობებში. მოდელირება შესრულდება გ. წულუკიძის სამთო ინსტიტუტსა და საქართველოს ტექნიკურ უნივერსიტეტში. აღნიშნული მოდელები შეავსებენ ერთმანეთს და დაგვეხმარებიან კრიტიკული სიჩქარის, უკუდინების სიგრძისა და გრადიენტ-ფაქტორის რიცხვითი სიდიდეების ცვალებადობათა კანონზომიერებების დადგენაში. ფიზიკური მოდელირებით მიღებული შედეგები შედარდება სრულმასშტაბიანი თანამედროვე საინჟინრო პროგრამული პაკეტების Pyrosim და Fluent-ის გამოყენებით მიღებულ რიცხვითი მოდელირების შედეგებს იმ მიზნით, რომ ახალი შედეგების გამოყენება შესაძლებელი გახდეს კონკრეტული გვირაბის გეომეტრიის, ადგილმდებარეობისა და ტოპოლოგიისათვის.

The paper considers various scenarios of fire development in road tunnels. The dynamics of combustion products propagation is studied by taking into account the fire strength, tunnel geometry and layout, and aerodynamics of the ventilation flow. The impact of strong fires on the sustainability and proper operation of ventilation systems is demonstrated, and different types of numerical models are considered with the FDS software environment. Theoretical and numerical experiments have demonstrated that strong fires in tunnels can induce dynamic pressures greater than the static pressures of the tunnel fans. The latter can change the direction of movement of ventilation flows in the tunnels with an inclination of 3% or more when the seat of fire is at a hypsometrical height lower than the air supply portal, thus drastically impairing the self-evacuation capability of people in the disaster zone. It was demonstrated that one of the most reliable ways to save lives in case of fire is to limit the spread of flue gases to prolong the time for evacuation. The paper proposes a transformable flexible system to save lives, which artificially increases the aerodynamic resistance of tunnels to prevent the propagation of harmful combustion products on the people’s evacuation route. By considering the fire development scenarios in horizontal and inclined tunnels, the dynamics of the spread of the fire damaging factors when ventilation system is no longer operable and the only solution is the use of the flexible system is examined. The results of modeling evidence that by closing 50% of the tunnel cross-section with a flexible system it is possible to obtain important positive results in reducing the spread of combustion products and saving lives. The use of the proposed system reduces the intensity of the spread of fire hazards and will definitely help the people in the disaster zone. The analysis carried out clearly shows its necessity and that the comprehensive study of fires and generalization of study results will be useful in adequate planning and implementing future measures to prevent and reduce their harmful effects. Following the above-mentioned, a detailed description, analysis and development of a clear algorithm of action of fire cases, and communicating the results to rescuers, tunnel service personnel and the general public are needed.

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