Abstract
Hypoxia problem has always been a difficult point in plateau tunneling projects. To solve this problem, a blind heading face in a plateau metal mine in western China was taken as the physical model, and the computational fluid dynamics was used to analyze the oxygen mass fraction distribution and oxygen-increasing effect in 1 m, 3 m, and 5 m roadway sections from the heading face. The optimal ventilation system was first built to obtain the optimum height and length of the airflow ducts. Then different cases with various oxygen supply duct designs were built in 2 scenarios. The results found that different oxygen supply duct design has significant influence on the oxygen distribution in the heading face. Also, each design has different optimal height of oxygen outlet. The oxygen supply effect is best when some small holes are made in the oxygen supply duct to diffuse oxygen to the working surface. The finding of this paper is helpful for effective and economical oxygen supply in roadway excavation of plateau metal mine and tunnel.
Highlights
Western China is a crucial strategic reserve base in metal mineral resources [1]
The engine power, traction characteristics, acceleration, and slope climbing performance of machinery constructed in high-altitude heading face are reduced dramatically. us, hypoxia has been a crucial concern in the plateau metal mine
As the height of the oxygen supply duct outlet rises to 1.8 m and 1.9 m, the area of relatively high oxygen concentration region gradually decreases, but the oxygen concentration of the breathing zone is basically guaranteed to reach the ideal level (5% higher than the local oxygen mass fraction)
Summary
Western China is a crucial strategic reserve base in metal mineral resources [1]. due to the adverse natural environment such as low pressure and subpar oxygen concentration caused by high altitude, the technical requirements and difficulties of plateau mine mining are high, and the construction is very difficult. erefore, the miners and mechanical equipment there are severely tested. Two methods were used in increasing oxygen mass fraction in the heading face in previous research: one is oxygen supply, and the other is pressurized ventilation. Few researches have been done to focus on the design and layout of oxygen duct in increasing oxygen with ventilation in plateau metal mines. For this reason, a study on increasing oxygen concentration in blind heading of a plateau metal mine by optimizing oxygen supply duct location is needed. (d) While the standard k-ε model is a high-Reynolds number model, the RNG theory provides an analytically derived differential formula for effective viscosity that accounts for low-Reynolds number effects Effective use of this feature does, depend on an appropriate treatment of the near-wall region. C1ε, C2ε, and C3ε are constants; generally, C1ε 1.44 and C2ε 1.92. e quantities αk and αε are the inverse effective Prandtl numbers for k and ε, respectively, and Sε are userdefined source terms
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