Research On Ventilation Control Strategy And Simulation Of Long Highway Tunnel Fire

With the development of highway industry in our country,the scale of highway tunnel tends to grow longer and longer.Compared with the short highway tunnel,the long highway tunnel not only has a long and narrow structure,but also has a large number of special constructions.Once the fire,it is difficult to rescue and easily lead to secondary disasters,which would create more serious consequences.Therefore,the disaster prevention and rescue of the long highway tunnel has always been the focus and difficult point in the research of the highway safety and sustainable development,which reflects the necessity and urgency of improving the technical level of accident prevention and emergency rescue.In this thesis,the advanced and mature technique of field simulation is applied to the simulation and analysis of long highway tunnel fire ventilation control by referring to the existing highway tunnel disaster prevention technology,other related data,and the research on tunnel fire ventilation control.The researches are mainly from the following several aspects:First of all,aiming at various special constructions in highway tunnel,the numerical simulation of the pressure loss of different density fluid in the special constructions is carried out and the function model of pressure loss coefficient is established by CFD,which plays an important role in the calculation of critical ventilation pressure under fire condition.At the same time,the jet fan's dynamic characteristics and its influence on the development of the fire are studied through the simulation,and the approximate model of jet wind force is established.Secondly,the fire grade of long highway tunnel is divided into four levels using maximum heat release rate,the dynamic development model and geometric model of fire source are established according to the analysis of the characteristics of fire.The velocity field and pressure field of highway tunnel fire without aerodynamic disturbance conditions are analyzed.The velocity peak function model of smoke longitudinal diffusion of tunnel roof and the static pressure peak function model of tunnel roof are established.Finally,the critical wind speed model is established through the calculation theory of the long highway tunnel ventilation,the reliability of the model is verified by the determination of no reflux through the calculation and simulation of the fore simulation results.The relevant ventilation control strategies are instituted according to the security decision model and the fire in different positions.