Study on Ventilation Parameter Optimization and Dust Migration Rule of Extra-Long Tunnel
The dust diffusion in the tunnel during construction has a great impact on the safety of personnel and the construction period.Especially in the excavation of long tunnels,selecting reasonable ventilation system layout parameters is the foundation for efficient and economical construction of the tunnel.This article took the Tiantai Mountain Tunnel of Baoji-Pingkan Expressway as the research background,used the fluid mechanics numerical software to establish a three-dimensional numerical model for calculating the migration rule of dust in the tunnel under different ventilation speeds,duct diameter,distance from the outlet of the duct to the tunnel face,and the suspension position of the duct,and conducted on-site practice.The research results indicate that both too high and too low supply wind speeds are not conducive to dust discharge from the tunnel,and the optimal wind supply speed is 30 m/s;the diameter of wind ducts has a significant impact on dust migration in the tunnel.The larger the diameter of the wind duct,the larger the initial jet and the greater the wind flow,which is more conducive to ventilation and dust removal;the farther the wind duct outlet is from the tunnel face,the more energy is consumed and it is less likely to carry dust out of the hole;the wind duct should be installed at the arch shoulder of the tunnel,so that the dust is not easily accumulated at the working face,which is conducive to dust removal and safe tunnel construction.
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