TBM Excavating Tunnel Of Airborne Rock Dust Pollution Diffusion Law And Control Research

A large number of rock dust will be produced during the construction of the full section tunnel boring machine(TBM).However,due to the unclear understanding of the airborne rock-dust transport law,and the existing TBM air-borne rock dust control technology has certain limitations and deficiencies,resulting in high concentration of rock dust production site has not been effectively controlled.In order to effectively reduce the rock dust concentration of in the TBM excavating tunnel construction,this paper used theoretical analysis,numerical simulation methods,combined with field application experiment of TBM tunnel construction of airborne rock dust pollution diffusion law and control technology research and optimization.The sources and physical and chemical properties of rock dust in TBM construction tunnel are explored.The particle size distribution of rock dust is obtained through experimental analysis,and the organic functional groups in rock dust and wetting property of rock dust are determined.Rock dust samples were analyzed,and mineral composition of rock dust was determined.The process of atomization in the nozzle and the mechanism of the dust particles settling in the fog droplets are studied.At the same time,the macroscopic characteristic parameters of the fog field are measured.The C2#nozzle with the aperture of 2.0mm and the internal structure with the X shaped diversion core is a better anti blocking nozzle,and the fine characteristic parameters of the spray field,such as the droplet diameter and velocity,are determined under different pressures,such as the droplet diameter and velocity,and the nozzle pressure is obtained.The force is 0.5MPa,the axial direction and the distance from the nozzle are in the range of 100mm?200mm.The D32 index of fog droplets is distributed in the range of 50?m?90?m,and the velocity of the fog droplets in the axial direction is concentrated in 10m/s?15m/s.Using FLUENT software of numerical simulation and analysis of the Qingdao metro line 2 of the actual use of TBM construction tunnel ventilation parameters within the general risk control effect of dust,it is concluded that under the parameter cannot satisfy the requirement of breathing,and rock dust pollution diffusion cannot be controlled effectively.Press by changing the secondary air flow and secondary tuyere location,study compound parameters under the TBM construction tunnel wind field and rock dust migration law of flow field,it is concluded that when the secondary pressure with after 8 m3/s air volume,air volume after 8 m3/s,the secondary pressure tuyere location is 60 m,dust control effect is best,and according to the results of simulation data,fitting out of the secondary wind pressure parameters and rock dust diffusion distance,the workspace,the average dust concentration mathematical relationship.The optimization scheme of the ventilation control dust system is applied to the project.After the optimized ventilation parameters are used,the concentration of rock dust in the working area is reduced to 2mg/m3 below,which meets the respiratory requirements of the personnel,effectively reduces the production site rock dust concentration,and significantly improves the working environment of the working area of TBM construction tunnel.