VENTILATION SYSTEMS OF TRANSPORT TUNNELS: CLASSIFICATION, STRUCTURE AND PRINCIPLES OF OPERATION

Аннотация

В статье рассматриваются виды тоннелей, особенности их вентиляции и применяемое оборудование. Основное внимание уделяется транспортным тоннелям, где вентиляция необходима для обеспечения безопасных условий движения и защиты от вредных выбросов. Описаны два типа вентиляции: естественная, основанная на тепловом напоре, и механическая, обеспечивающая подачу и удаление воздуха с помощью вентиляторов. Подробно представлены осевые и струйные вентиляторы, их конструкция, принципы работы и преимущества. Рассматриваются схемы вентиляции: продольная, поперечная и комбинированная, каждая из которых имеет свои плюсы и недостатки. Особое внимание уделено противопожарной защите и удалению дыма при возникновении пожаров. Указано, что выбор системы вентиляции влияет на размеры и конструкцию тоннеля, поэтому определяется на раннем этапе проектирования. Материал может быть полезен для специалистов в области строительства и эксплуатации подземных транспортных сооружений. 259 INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR RESEARCH & DEVELOPMENT SJIF2019:5.2222020:5.5522021:5.6372022:5.4792023:6.5632024:7,805 eISSN:2394-6334 https://www.ijmrd.in/index.php/imjrd Volume12,issue04(2025) Ключевые слова: Тоннель, вентиляция, транспортные сооружения, осевые вентиляторы, струйные вентиляторы, естественная вентиляция, механическая вентиляция, продольная вентиляция,поперечная вентиляция Tunnel- this is an underground or mountain-like enclosed structure, usually built to provide for themovement of vehicles (cars, trains) orpedestrians. All tunnelshave several safety systems, oneof which is theventilation system. Themain tasks ofventilation in tunnels are: ensuring the necessary cleanliness and temperature, pressure, humidity, and air velocity in the tunnel; significant reduction of the content of harmful substances in the transport zone and in the air discharged from thetunnel at thelocations ofair outlets(ventilation corners);  ensuring the rapid removal of combustion products, smoke removal, and assistance in evacuating people inthe event ofa fire; Preventing freezing of roads, tunnel equipment, and operational equipment in areas with cold climates. Ventilation systems and equipment in large tunnels can account for up to 30% of their costs. Ventilation in transport tunnels isprovided bynatural ormechanical methods. 1. Natural ventilation of tunnels occurs under the influence of thermal pressure, which is created by the temperature difference between the tunnel and the outside air. Its effectiveness largely depends onthe geographical and altitude conditions ofthe tunnel location, thelength of thetunnel, as well as thenumberand volumeof moving traffic, as well as otherfactors. 2. Mechanical ventilation of tunnels (artificial ventilation) is carried out by supplying fresh air through airexchange, removing polluted air, or simultaneously supplying clean andwaste-free air. In tunnels up to 300 m long, natural ventilation is allowed, in tunnels longer than 300 m, the issue of ventilation is resolved before the design of tunnel structures, since the choice of ventilation system in most cases determines the dimensions of the tunnel section. Therefore, first the ventilation system is installed, the amount of air required for ventilation of the tunnel is calculated, the required cross-sectional area of ​ ​ the ventilation ducts is determined, and the cross- sectional dimensions of the tunnel are calculated. In addition, when designing the tunnel, it is necessary to provide for mechanical devices that will remove toxic smoke from the tunnel in the event of afire. Theparameters ofthe smokeexhaust system are also determined bycalculation. Free ventilation is ventilation in which air flow occurs without fans or mechanical means, due to thefollowing physical phenomena: 1. Temperature difference - the difference in air temperature between the indoor and outdoor environment (especially noticeable in thewinter season). 2. Windpressure -the force ofwind blowing through open openings. 3. Thermal convection -hot air rises and cold airsinks, creating anatural current. The design air pressure in the tunnel is determined as the algebraic sum of all aerodynamic resistances created in the transport zone, longitudinal and transverse channels during air exchange and air distribution, as well as due to natural air draft. Additional data that must be taken into account in aerodynamic design: meteorological parameters, barometric pressure difference and wind. Artificial ventilation of tunnels involves the removal of all harmful gases and dust particles from thetunnel byartificially creating an air flowusing mechanical fans. Advantages:  Lowconstruction and operating costs.  No electricity required. 260 INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR RESEARCH & DEVELOPMENT SJIF2019:5.2222020:5.5522021:5.6372022:5.4792023:6.5632024:7,805 eISSN:2394-6334 https://www.ijmrd.in/index.php/imjrd Volume12,issue04(2025)  Maintenanceis easy due to thesimplicity ofthesystem. Di