Study On The Fire Separation Of High Expansion Foam In The Utility Tunnels

Through the review of the relevant papers of the utility tunnel,I classified the kind of municipal pipelines,which have been usually taken into the built utility tunnels.Because the pipelines in most utility tunnels were water pipe,communication cable,power cable,the fire risk in utility tunnels can be simplified and the fire type can be considered as the cable fire,like the cable tunnels.Besides,the automatic fire extinguishing systems were introduced which are commonly used in the utility tunnels,and compared the advantages and disadvantages of the listed fire extinguishing systems with the high expansion foam system.In order to improve the high expansion foam system adaptability,a vertical arrangement of high expansion foam generator set in the hole outside the utility tunnels was carried out.This setting way solved the problems,such as the narrow space of utility tunnels etc.,and had other advantages,such as enlarging the selection range of the foam generator,reducing the cost,and supplying foam directly which was damaged by fire.Additionally,the feasibility of this application was proved by theoretical analysis and experiment in the mode of small size.On the base of feasibility,the design parameters were studied,such as the foam expansion ratio and the feasible range of foaming rate,which were needed of the high expansion foam system in utility tunnels,by the small scale experiments,theoretical calculation,theoretical analysis and other research methods.As a conclusion,the foam whose foaming ratio is over 200 can piled up in the utility tunnels and the function relation between flowing rate and foam expansion ratio was fitted.The destruction rate of foams is mainly affected by the foam expansion ratio and fire power.Furthermore,3 different kinds of specific setting mode were listed,and the set spacing and the economical efficiency were studied through numerical simulation,theoretical calculation and theoretical analysis.It was considered that the movable layout No.2 has relatively high economic performance,and the reliability of the fixed layout was greater than the others.