Борис Борисович Колчев
◽
Андрей Владимирович Пехотиков
◽
Игорь Иванович Ильминский
◽
Павел Алексеевич Чернышов
◽
Оксана Владимировна Фомина
Одним из нормативных документов, содержащих основные требования к системам противодымной вентиляции автодорожных тоннелей, является NFPA 502 «Standard for Road Tunnels, Bridges and Limited Access Highways». Стандарт обобщает накопленный опыт, полученный в результате экспериментальных исследований, проводимых как в США, так и за их пределами. В августе 2019 г. была опубликована его новая редакция (2020 Edition), в которой значительно изменился подход к определению требуемых параметров противодымной вентиляции, основанной на продольной схеме.
The article presents an analysis of the new edition of NFPA 502 “Standard for Road Tunnels, Bridges, and Limited Access Highways” regarding the method for determining the critical value of the longitudinal air flow velocity generated by smoke ventilation based on longitudinal scheme. The classification of road tunnels introduced by NFPA 502 is described, taking into account the occupancy of tunnels by vehicles during rush hour, as well as the length of the tunnel. The data concerning protection of tunnel by fire protection systems taking into account the introduced classification are presented. There are analysed the schemes of smoke ventilation, including longitudinal, semi-transverse and transverse, containing different number of concentrated and distributed smoke receiving and air intake devices introduced by NFPA 502. There is described the effect of trapping air from under the smoke layer, that is called as “Plugholing” effect in the standard. The data on heat release capacity from fire source are presented taking into account various types of burning vehicles, as well as the equipment of tunnel with automatic fire extinguishing systems. There is performed the comparison of results of the calculated determination of critical velocity, determined by the dependencies of NFPA 502 in 2017 and 2020 editions. The significant discrepancy in required values is found.