Monitoring And Numerical Simulation Of Distribution Of Dust Concentration In Rock Drift Tunneling

With the development of high yield and high efficiency in coal mine, the dust concentration generated in tunnel excavation construction is becoming higher. High dust concentration will cover the work line of sight and affect the operation of workers, tiny dust will damage the mechanical equipment, high concentration respiratory dust is a serious threat to the workers in working face, dust control has became the focus of prevention and control work. The dust generated in both tunneling working face excavation and construction of shotcrete are studied. The mechanisms of dust production, link and position and control technology in the process of excavation and bolting are studied and discussed. Fluent software is used to simulate the dust concentration changes in the process of tunnel excavation construction. The main conclusions are as follows:(1) The dust gengreated in rock drift tunneling is mainly derived from the tunnel excavation construction and construction of shotcrete, the drilling process in drilling and blasting construction and fully mechanized workface construction will produce a large of dust. In addition, working face ventilation, rock fragments, the transfer machine and shotcrete nozzle and other reasons will also produce dust, and the spraying machine and artificial mixing material will increase the dust concentration in the tunnel.(2) Inside and outside atomization and the long pressure short smoke ventilation system and dust collector are three mainly dustfall measures in the process of tunnel excavation construction. The dustfall measures in transshipment point mainly includes decrease the gap between two transfer point and sprinkling water and sealed dust-exhaust. Dust-depressor is used to control the dust diffusion by adsorbing the dust. The dustfall measures in the construction of shotcrete mainly includes four methods: choosing reasonable wind pressure and water pressure, controlling the distance between the nozzle and the wall of the roadway, damp material is used in the mixing system, select the reasonable wind speed.(3) In the numerical simulation of the ventilation by high presseure, the law of total dust concentration and the concentration of respiratory dust are basically the same, but the particle size of respirable dust with small mass is less than 5μm, and it has little influenced by the gravity, so it is difficult to subsidence and easily suspended in roadway under air effect. Compared with the field test and experiment tests, the numerical simulation has less investmen and is a very good supplement effect.