Numerical Simulation And Optimization Of Ventilation And Dust Exhaust In Long Distance Tunneling

The harm of blasting dust is always a big problem in the process of underground mining.The composition of blasting dust is complex,containing a variety of toxic and harmful substances,and its harm is far greater than that of the dust in the general workplace,especially in the long-distance excavation of the roadway.In the process of long distance tunneling,there are a great deal of air leakage and air flow energy loss,which lead to the lack of fresh airflow in the tunneling face.At the same time,the structure of airflow field in the tunneling face is complex,and the effective utilization rate of airflow is reduced by unreasonable ventilation layout.Therefore,the analysis of wind flow field and the optimization of ventilation layout in the long distance tunneling face are of great significance for the safety of mine ventilation.In this paper,combined with the actual blasting and ventilation of a copper mine,relying on the theory of CFD,using Fluent software for transient simulation and analysis of the movement of the roadway dust,intuitive show the movement of dust in the roadway.By changing the hanging position of the air duct in the roadway,the distance between the air duct mouth and the heading end face,the size of the air duct mouth and the use of pulse ventilation,comparing the effect of ventilation and dust removal under different conditions and quantitatively analyzing the dust retention in the roadway,the optimal ventilation layout parameters of the roadway are obtained,and finally the optimal ventilation layout scheme of the roadway is determined.The conclusions are as follows: The jet flow field in the blind roadway is the attached jet flow in the confined space,which is divided into the attached jet flow area,the impact jet flow area and the backflow area.Under the condition of tunnel ventilation,the dust discharge time of tunnel is greatly reduced,but the disturbance effect of airflow on dust is not conducive to the self-deposition of dust.The duct hanging at the height of 2.0m on the side wall of the roadway is conducive to the rapid discharge of dust in the short term,and the duct hanging at the middle of the top of the roadway is conducive to reducing the minimum dust concentration in the roadway at the late stage of ventilation.The distance between the inlet of air duct and the end face of heading is 13 m,which is favorable for the discharge of dust in roadway.Shrinkage wind duct mouth for the ventilation of the roadway dust is favorable,the appropriate size of wind duct mouth diameter is d=0.6 m.Relative to the stable air outlet of the air duct,the use of pulsating air outlet is conducive to the discharge of dust in the roadway;The larger the amplitude of airflow pulsation is,the more dust is discharged from the tunnel;The best ventilation pulsation period of different ventilation time decreases with the ventilation time prolonging.Generally speaking,with the decrease of ventilation pulsation period,the effect of ventilation and dust removal in the tunnel is better.The optimized scheme of drivage roadway ventilation is determined as follows: the air duct is placed in the middle of the roadway top,the distance between the air duct mouth and the heading end face is 13 m,the diameter of air duct mouth is d=0.6m,and the pulsating period of pulsating ventilation is T = 0.5s,and the pulsating amplitude is F = 7.1m/s.