Abstract
To exploit the influence of the tunnel face and the distance between the diameter and the orifice of a blast pipe on the ventilation effect in symmetric tunnel construction, this paper uses Fluent to establish a three-dimensional model and numerical simulation. Firstly, the accuracy of the numerical simulation is tested and then the distance between the orifice and tunnel face and the influence of the air duct diameter on the ventilation effect are studied, respectively. The results show that the ventilation effect is best when the wind pipe is arranged on one side of the tunnel wall (an asymmetrical layout), although the space in the tunnel is axisymmetric, and that the error of the numerical simulation is less than 5% of the measured value. When the distance between the orifice and tunnel face is 5 m, the uniformity of the air flow field near the tunnel face is poor; when the distance is 10 m and 12 m, an obvious vertex area appears in the tunnel. Furthermore, the uniformity of the wind velocity flow field is optimal when the distance is 8 m. When the air duct diameter is less than 1.4 m, there is a uniformity of the flow field near the tunnel face of the upper and lower benches; when the air duct diameter is more than 1.4 m, the tunnel face of the upper bench near the ground shows more obvious backflow. Therefore, it was determined that taking the air duct diameter as 1.4 m and the distance between the orifice and tunnel face as 8 m was the best combination for the design of ventilation in this project. It was also found that a better ventilation effect can be achieved when the distance between the nozzle of the ventilator and the tunnel face is 6 m–9 m and the wind speed of the nozzle is 6 m/s–8 m/s. In practical engineering, the wind speed and the required air volume should be taken into consideration to determine the diameter of the ventilator.
Highlights
Taking practical, economical, and safe ventilation measures are essential in the process of tunnel construction
Tan et al [1] researched the distribution of dusts and harmful gases in tunnels after construction blasting that used the drilling and blasting method; Peng et al [2,3] analyzed the forced ventilation effect of tunnels in construction using the positive bench method and put forward the notion that the ventilation effect is best when the air duct layout is along the sidewall of the tunnel and the distance to tunnel face is 5 m–10 m
We found that the ventilation effect is best when the wind pipe is arranged on onethe side literature and numerical simulation
Summary
Economical, and safe ventilation measures are essential in the process of tunnel construction. Et al worked on numerical and fieldon measurement research on field measurement research on tunnel construction [13], Zhang et al [14]. Conducted tunnel construction ventilation [13], Zhang et al [14]ventilation conducted numerical simulation research on numerical simulation research on the ventilation flow field of gas tunnel construction. Selection of optimal alternatives for the mechanical longitudinal ventilation tunnel pollutants, studied the of the operation tunnel the case of fire [16,17], Cardillo et al.in [18]. The related conclusions in this paper are of utmost from the tunnel face for numerical simulation research. The related conclusions in this paper are of importance in guiding the ventilation scheme formulation of urban tunnel construction. Utmost importance in guiding the ventilation scheme formulation of urban tunnel construction
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