Study On Fire Smoke Control Of Highway Tunnel With Rectangular Section

In recent years,my country’s tunnel construction technology has developed rapidly,and various types of underwater highway tunnels have continuously emerged,and their length and construction scale have also been increasing.These long tunnels not only improve travel efficiency and economic benefits,but also bring certain safety operation challenges.In particular,tunnel fire accidents seriously endanger the safety of public lives and property.The smoke exhaust and smoke control technology for large rectangular cross-section tunnels is currently There is little research.Therefore,this dissertation takes the smoke exhaust control under the fire condition of a large rectangular section tunnel as the research object.Through theoretical analysis,numerical simulation and reduced-size model test,the traffic blocking condition(side concentrated smoke exhaust mode)and non-traffic Tunnel fire smoke control under blocking conditions(combined mode of longitudinal ventilation and side centralized smoke exhaust)was analyzed and researched,and it provided reference and data support for smoke exhaust design and safe operation management of rectangular large-section tunnels under fire conditions.The main research contents are as follows:(1)According to the actual structural form and design situation of the project,a 1:1 FDS numerical model and a 1:15 scale reduction test model were established.By consulting relevant specifications and previous research results and other materials,designing test conditions,equipped with measurement systems and electromechanical systems,a large rectangular section tunnel test platform was built.(2)Research on the key technologies for setting up smoke vents in the side centralized smoke exhaust mode.Through numerical simulation and model experiment,the smoke extraction efficiency of the smoke extraction system,the smoke spreading range in the tunnel,the spreading speed and the temperature distribution under different setting parameters(height,area,layout)of the smoke outlet are compared and analyzed.The study found that under the condition of a certain amount of smoke exhaust,the area of the exhaust vent has no obvious influence on the smoke exhaust effect;the uniform arrangement of the exhaust vents and an appropriate increase in the height of the exhaust vent are beneficial to the smoke exhaust of the tunnel.(3)Research on the change law of the critical wind speed of tunnel fire under the synergistic effect of longitudinal ventilation and side concentrated smoke exhaust.Firstly,through non-dimensional analysis,the relevant factors of critical wind speed are simplified and analyzed,and the non-dimensional formula is obtained;secondly,through numerical simulation,it is found that in the non-dimensional state,when the heat release rate of the fire source is not greater than 0.14,the critical wind speed is increased with The 1/3 power of the release rate shows a linear increase trend,but when the heat release rate of the fire source is greater than 0.14,the critical wind speed change tends to be stable,and combined with the dimensional analysis and simulation calculation results,the longitudinal ventilation and side concentration are established.The prediction model of tunnel fire critical wind speed under the synergistic effect of exhaust smoke;finally,the reliability and applicability of the prediction model in this paper are verified by comparing the results of the scaled-down model test and the critical wind speed prediction model built by the predecessors.(4)Study the influence of the longitudinal tunnel slope on the critical wind speed under the synergistic effect of longitudinal ventilation and side concentrated smoke exhaust.Calculate the critical wind speed under different tunnel longitudinal slopes(0% gradient,±1%gradient,±2% gradient and ±3% gradient)through FDS simulation,analyze the smoke spread and temperature distribution in the tunnel,and clarify the criticality of the tunnel longitudinal slope The influence of wind speed,and then the slope correction of the critical wind speed prediction model established above.