Study On Key Ventilation Technology Of Extra-Long Highway Tunnel Construction At High Altitude

In recent years,along with the formation of China’s highway transportation network,the highways have been deep in the hinterland of Sichuan,Xinjiang and Tibet.Due to special geological conditions,more and more highway tunnels were built in the High-altitude area of western China.The tunnel construction of high altitude area is different from the general plain area,especially the application of construction ventilation technology.Under the condition of low pressure hypoxia,large tunnel length and poor construction conditions,the construction ventilation technology has become the technical problem of high elevation highway tunnel construction.Therefore,this paper studies the key technology of construction ventilation of high altitude special highway tunnel based on snow mountain beam tunnel project.In this paper,the method of combining literature survey with monitoring measurement is adopted,and computational fluid dynamics(CFD)finite element software is used to analyze the actual project.The main research contents and conclusions are as follows:1.The main research methods and research status of high altitude tunnel construction ventilation are summarized.The pollution control standard of ventilation in highway tunnel construction is summarized.This paper analyzes the basic theory of tunnel construction ventilation based on fluid dynamics and provides theoretical support for the study of ventilation technology in the tunnel engineering of snow mountain beams.2.This paper sums up the main ventilation methods and ventilation equipment at high altitude tunnel construction at the present stage,puts forward the design principles of ventilation in high altitude tunnel construction,sums up the calculation formula of climate parameters and calculation formula of construction ventilation parameters under high altitude environment,and studies the ventilation parameters correction formula of tunnel construction at high altitude.Through the above studies,the plateau environment parameters were calculated and revised for the Xueshanliang tunnel project,and the construction ventilation plan was redesigned and optimized.The two-stage ventilation scheme of push-in ventilation and no-tidal roadway type jet ventilation was proposed and effectively improved.Dust emission and insufficient oxygen supply during tunnel construction.3.Monitoring of dust,harmful gas concentration and wind speed in tunnel ofXueshanliang tunnel is monitored.During the tunnel construction cycle is obtained,the process of dust and the spread of the poisonous and harmful gas with time and space change rule and the size of wind speed,and the current ventilation under the condition of ventilation effect and provide experimental data for the numerical simulation to further study.4.Using the computational fluid dynamics(CFD)finite element software Fluent,the numerical simulation of the construction ventilation section of the Xueshanliang tunnel project was carried out.The ventilation structure and dust in the tunnel during the two-stage ventilation project of push-in ventilation and roadway ventilation were analyzed.The law of transport of toxic and harmful gases in time and space and verify the rationality of ventilation methods.Through numerical simulation and comparison of monitoring data,a suitable dust-reduction measure was proposed in conjunction with the ventilation scheme,which effectively reduced the concentration of pollutants.Through the optimization design and parameter correction of the construction ventilation,it provides the theoretical basis and technical support for the construction ventilation technology of the Xueshanliang tunnel,which ensure the tunnel constructor’s personal safety,offer technology support for the efficient fast and safe construction of the tunnel in Xueshanliang tunnel,and provide valuable reference for other similar ventilation technology of high-altitude tunnel construction.