| With the rapid development of urban traffic construction in China,the development and utilization of urban underground space has also accelerated the pace,in which underwater tunnel construction has made remarkable achievements,a large number of river bottom,lake bottom,submarine tunnel emerged out.As the sea tunnels are becoming more complicated,the probability of fire and traffic accidents is increasing.Due to underwater tunnel is generally "U" shape and the structure is closed,the other traffic condition is complicated,the disaster is difficult to control and heavy losses in the event of fire,so the underwater tunnel smoke controlling technology has become a key factor in safe operationBased on the Mawan sea tunnel,the method of data research,empirical formula and numerical simulation is adopted to study exhausting technology and evacuation of underwater tunnel,which include open excavation section,single layer shield section and double shield section,the research work of this thesis is as follows:(1)Through the data,research has been the current underwater tunnel smoke technology that has formed the mode that" longitudinal exhausting at both ends of the open excavation + concentrated exhausting in shield section," personnel evacuation has formed the mode that" cross-channel evacuation in the open excavation + stairs(slides)in the shield tunnel ",the paper defines the basic parameters of fire FDS and personnel Pathfinder simulation.(2)In this paper,the characteristics of the flue gas flow and the tolerance limit are studied by opening hole section at the top of the tunnel,and the optimal controlling velocity of the corresponding main tunnel,ramp 6 and ramp 4 is obtained.By setting the opening section in the condition that one-way spreading,the main tunnel within the velocity 3.5m/s is less than the 4m/s controlingl velocity when the tunnel does not contains openings;When the two-way symmetrical spreading,the first 10min flue gas symmetry spreading condition is well,but the physiological indicators seriously exceed the human tolerance limit.(3)Based on the single-layer shield tunnel model,the parameters of the best exhausting port are obtained according to the exhausting efficiency and the exhausting velocity.The critical velocity of the single-layer and double-layer shield tunnel in the longitudinal ventilation is obtained respectively,exhausting volume of opening the upper and lower exhausting port and only opening the lower exhausting port.According to the CO volume concentration,the visibility of human eye height and the human eye height temperature,ASET curve has been got,law that the timely opening of the fire point just above the exhausting port is more conducive to smoke controlling and evacuation has been summed up.(4)Through the Pathfinder simulation software,the optimal cross-channel spacing of 240m is obtained,and the optimal staircase spacing of single-layer shield section and double-layer shield section is 80m.Based on the method of using the slides as a staircase,the paper studies that the single-layer shield tunnel combination evacuation mode:the cross-channel+staircase,the staircase+the staircase and the cross-channel spacing.The staircase spacing is obtained from the bottom-up evacuation mode of double shield tunnel,and the RSET curve is obtained accordingly.By comparing the empirical formula,the reliability of the simulation results is verified.It is concluded that the safety of opening the upper and lower exhausting port is the highest,and only the opening the lower exhausting port is the second,the longitudinal exhausting(opening no exhausting port)is the least safe. |
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