| The complex tunnels extend in all directions,the fire locations are diverse,the fire source downstream branches are numerous,resulting in the high temperature flue gas influence scope is wide and difficult to control.In order to give consideration to the smoke extraction efficiency and economy,and to reduce the influence of smoke extraction wells and other facilities on the upper part of the tunnel,longitudinal smoke extraction can still be used in complex tunnels.However,how to carry out longitudinal smoke exhaust design for complex tunnels has been less studied in the academic circle,and the accumulated experience in the engineering field is not enough,relevant norms also lack targeted provisions.If the unreasonable longitudinal smoke exhaust design is carried out,the uneconomical selection of fans and the unreasonable fan schemes will increase the initial investment and operating costs,it even causes more damage from fire than regular tunnels.The existing longitudinal smoke exhaust designs mostly aim at specific structures and specific fire locations,and it is difficult to comprehensively deal with a variety of tunnel fire scenarios.This paper applies the zoned control method in the complex tunnel longitudinal smoke exhaust,and puts forward the division principle and method of longitudinal Smoke exhaust zone.On the one hand,it can reduce the distance of smoke emission and solve the problem of the spread of smoke emission in the longitudinal direction.On the other hand,it can simplify the smoke emission facilities and the opening and closing scheme of the fan,so as to achieve the result of considering the smoke emission efficiency and economy.In this paper,theoretical analysis and numerical simulation are mainly used to study on longitudinal zoned smoke control and the matching calculation of jet fan in complex tunnel,and the design method of longitudinal zoned smoke control for a variety of complex tunnel is obtained.Research contents and achievements include the following aspects:(1)In accordance with characteristics of the traffic flow and tunnel lines,complex tunnels are divided into several basic structure units,division principle of Smoke exhaust zone are proposed according to the basic structure unit and unit combination extraction principle.(2)Through the principle of pressure balance and flow balance to determine the opening fan direction,the fan coordination relationship in the adjacent smoke exhaust partition and the fan selection range of the basic structural unit,to provide a theoretical basis for the complex tunnels.(3)Give the division principle of multi-ramp tunnels smoke exhaust zone and jet fan matching calculation process,through the numerical simulation to prove the proposed method in the multi-ramp tunnels applicability.(4)The method proposed in this paper is applied in UTLT,it is transformed into a multi-ramp tunnel through the upstream shunting point,and the same upstream shunting point corresponds to the fire in the same smoke extraction section,the numerical simulation proves that the smoke extraction and smoke prevention effect can be achieved;(5)The idea of complementary smoke exhaust is perfected on the basis of opening the cross passage of fire upstream in the double-hole tunnel for evacuation,numerical simulation prove that the longitudinal zoned smoke control in double hole tunnels can achieve good effect of disaster prevention,and satisfy the purpose of double hole tunnel fan power complementary.In this paper,the design concept and realization method of longitudinal zoned smoke control in complex tunnels are presented. |
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