Study on Multi-factors Affecting Construction Ventilation in Hydraulic Tunnels with Gas in Tingzikou Irrigation Area
Based on the typical tunnels with gas in the Tingzikou irrigation area,the ventilation effect in tunnels with gas was simulated based on CFD software,obtaining the ventilation flow field and gas concentration distribution field.By controlling the distance between the air pipe outlet and the working face,the diameter of the air pipe,the air velocity at the outlet,the distance from the wall,and the angle of air pipe arrangement,the gas distribution law inside the tunnel was studied.The results show that:(1)Both the increase in the diameter of the air pipe and the air velocity at outlet can effectively dilute the gas accumulated at the working face,reducing the maximum gas concen-tration in the tunnel.However,if the air velocity is too high,the improvement in the dilution effect is limited.(2)As the distance between the air pipe outlet and the working face increases,the maximum gas mass fraction in the tunnel decreases first and then increases.As the distance from the wall increases,the maximum gas mass fraction in the tunnel shows an overall upward increase trend.(3)At a 75°angle between the air pipe and the horizontal plane it is most conducive to gas dilution,while a horizontal installation of air pipe is least favorable.The angle of the air pipe arrangement has the relative smallest impact on the gas concentration in the tunnel.(4)Considering the composite influence of multiple factors,under the factors and levels of this orthogonal test,the distance from the wall has the greatest impact on the ventilation effect in the tunnel,followed by the distance between the outlet and the working face,and the least is the air velocity at the outlet.
Tunnel with gasNumerical simulationVentilation flow fieldConcentration distributionInfluencing factors
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NSTL
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