| Since the 21 st century,thanks to the huge demand for the construction of China’s transportation network,China’s tunneling industry is also in full swing.With the needs of social development,more and more submarine immersed tube tunnels appear in people’s vision,but the problems of ventilation and smoke exhaust,disaster prevention and mitigation of submarine immersed tube tunnels are still one of the important problems that restrict their rapid development.Compared with ordinary mountain tunnels,immersed tube tunnels have a more complicated tunnel structure,stronger sealing and fewer entrances and exits.Once a fire occurs in an immersed tunnel and cannot be controlled,the consequences will be unimaginable and will inevitably lead to huge losses of people and property.Therefore,the study of fire ventilation and smoke exhaust in immersed tunnels is of great significance.In this paper,taking the Shenzhong Passage and the Hong Kong-Zhuhai-Macao Bridge tunnel as the actual supporting project,the fire numerical simulation model of the main tunnel and the ramp tunnel is established based on the fire numerical simulation software.The smoke exhaust effect of different smoke exhaust methods was studied and analyzed.This article proposes three different smoke extraction methods for the main tunnel of the immersed tunnel,studies the influence of different fire source powers and different tunnel widths on the smoke exhaust performance of the main tunnel of the immersed tunnel,and analyzes the flow characteristics of fire smoke in the main tunnel,Proposed a flue gas emission efficiency based on the conservation of CO mass in flue gas.By comparing the smoke spread,CO concentration distribution,visibility distribution and smoke extraction efficiency between the three different smoke extraction methods,it can be determined that the top smoke extraction method in the main tunnel of the immersed tunnel has the best smoke extraction effect,while the side The wall smoke exhaust plus the vertical wall smoke exhaust method has a better smoke exhaust effect than the single side wall smoke exhaust method.The article also studied the influence of different main tunnel widths and different fire source powers on the ventilation effect in the immersed tube tunnel.For the ramp of the immersed tunnel,six different smoke extraction schemes are proposed.By comparing and analyzing the ramp smoke spread between different smoke extraction schemes,the temperature distribution of key sections,CO concentration distribution,visibility distribution and velocity distribution,the research The effects of different smoke outlet arrangement methods,different smoke outlet numbers,different smoke exhaust areas and different smoke blocking measures on the exhaust of tunnel ramps are discussed.The results show that increasing the smoke exhaust area at the large cross section of the tunnel at the intersection of the main ramp and the sub-ramp can improve the smoke exhaust effect of the ramp,and adding smoke blocking measures can better concentrate the flue gas and also play a role in the smoke exhaust effect of the tunnel ramp Positive effect,but it will increase the thickness of the smoke layer on the top of the tunnel. |
