Numerical Simulation On Mixed Ventilation After The Blasting Of Excavation Tunnel

In mine engineering, blasting is a common method of tunneling construction, blasting fume make the downhole operation environment worsen, it is one of the important factors that threat to safety production of mine. In order to improve labor productivity and ensure mine safety production, we must implement effective ventilation after the excavation blasting to dilute and discharge the fume quickly. Mixed ventilation of large section roadway or tunnel is an effective ventilation method. So the thesis using computational fluid dynamics software to systematically study the mixed ventilation, investigating ventilation time, tuyere location, and the air volume on the influence of the fume exhaust effect, obtaining the migration regularity and distribution of blasting fume,and comparing mixed ventilation with forced ventilation.According to the numerical simulation of the blasting fume concentration field, in the mixed ventilation of excavation tunnel, blasting fume concentration and the distribution is closely related to the flow regularity of wind. Blasting fume concentration successively fall with the flow of wind, it is directly related to wind speed and the manifold. Blasting fume concentration is low in the area that the wind speed is large, however, blasting fume concentration is high in the area that the wind speed is small and the streamline is circular.Investigating the main influence factors of fume exhaust effect and from the simulation results:,①Ventilation time and blasting fume concentration accords with negative exponential function relationship.②Fume exhaust effect varies with the position of pumping and pressing tube.③Air volume and blasting fume concentration accords with negative exponential function relationship.Compared mixed ventilation with forced ventilation on fume exhaust effect, we can see that blasting fume is absorbed by the pumping tube and discharged by the ram when using mixed ventilation. Blasting fume is basicly controlled between tunneling face and pumping tube and fume exhaust time has nothing to do with the tunneling length. However, using forced ventilation, blasting fume pollute the whole tunnel because blasting fume flow along the tunnel and discharge from the outlet. It makes fume exhaust time extended along with the increase of the tunneling length.The research results of the thesis have practical guiding significance to the design and application of excavation roadway or tunnel mixed ventilation. They can be applied in the similar projects.