Optimization And Simulation Of Construction Ventilation For Highway Gas Tunnel

Abstract:Our country is a mountainous and hilly country, of which nearly75%of the land area is mountains and hills. Most of the highway traffic engineering constructions need to use tunneling technology. It is more important to optimize ventilation design of gas tunnel because of the risk of gas in tunnel construction, when tunnel through the coal seam area. According to a highway gas tunnel project, highway gas tunnel ventilation optimization is analysed by using theoretical analysis and numerical simulation method. The main research results are as follows.(1)Combined with a highway gas tunnel engineering, the tunnel construction ventilation parameter calculation is completed. The tunnel ventilation numerical model is established by using Fluent.(2)The distribution of tunnel airflow flow field is obtained with numerical simulation. It verifies that the pressure-tunnel ventilation airflow has obvious characteristics of wall jet, limited reflux and limited wall jet. There are three zones in gas tunnel ventilation airflow field which are eddy zone and impact eddy zone and stable zone.(3)The distribution of tunnel gas concentration is obtained with numerical simulation. Gas distribution has large differences in the three regions. Eddy zone has a significant impediment for gas diffusion. Gas diffusion in tunnel has a certain regularity, which can be simply summed up as moving and diffusing of two superimposed process. The movement of gas from face to entrance show two superimposed process of moving and diffusing.(4)The gas concentration of tunnel face is used as characterization factor. Orthogonal experiment scheme is determined with three factors, which are duct diameter, distance from duct mouth to tunnel face and duct hanging position. On the basis of orthogonal experiment results, the significant influence sequence of factors was identified by using range and variance analysis. What’s more, the optimal scheme of fan drum was obtained and proved.(5)A lot of highway gas tunnel ventilation effective measures and methods to design optimization and management are presented. It provides a theoretical basis for gas tunnel ventilation design and management.