Analysis Of Influencing Factors Of Construction Ventilation Of Large Cross Section Tunnel And Program Optimization Research

The development of my country’s economy is inseparable from the support of infrastructure construction.In the process of highway transportation construction,more and more large-section tunnels have emerged.In the process of drilling and blasting of large-section tunnels,harmful substances such as carbon monoxide and dust generated by blasting and excavation pose serious hidden dangers to the physical and mental health of tunnel operators,and at the same time affect the smooth development of tunnel construction.Therefore,the ventilation problem of large-section tunnel construction has become a problem that cannot be ignored in the tunnel construction process.In view of this situation,this paper uses computational fluid dynamics software Fluent to study the ventilation scheme of large-section tunnel construction.The main contents include the following aspects:(1)Explain the main pollutants and ventilation hygiene standards during tunnel construction,analyze the main influencing factors of tunnel construction ventilation,introduce the basic theory of computational fluid dynamics,compare the types and characteristics of turbulence models,and verify the validity of the numerical analysis models.(2)Combining the actual engineering of a large-section highway tunnel,determine the tunnel construction ventilation simulation parameters and boundary conditions,and establish a press-in ventilation model for the tunnel under the double-side pilot tunnel construction method.The tunnel ventilation process is presented through numerical simulation.(3)Analyze the numerical simulation results of tunnel ventilation,study the distribution law of the wind flow field and the carbon monoxide concentration field in the tunnel,and compare the influence laws of different pilot pits,step lengths and the hanging position of the air duct on the wind flow field and the dilution and diffusion of carbon monoxide concentration in the tunnel.(4)Based on the numerical simulation results of the large-section tunnel under the double-side heading method,the four factors of the tunnel construction method,the hanging position of the air duct,the distance between the air outlet and the tunnel face,and the wind speed of the air outlet of the air duct are selected for orthogonality.In the test simulation,the average concentration of carbon monoxide near the tunnel face was used as a measurement index,and the range analysis was used to obtain the primary and secondary order of the influence of various factors,and the optimization scheme and reasonable ventilation time under each construction method were obtained.Based on the tunnel construction ventilation problem,this paper adopts the research method of the combination of theoretical analysis and numerical simulation to optimize the construction ventilation plan of the large-section tunnel,and provides a reference for similar tunnel construction ventilation problems.