Abstract: Blasting construction in tunnels always induces overstandard dust concentration and difficulty in dust removal. Therefore, in this study, a new threesection spray system is designed, and its relevant parameters are studied. Based on a selfbuilt spray dust experimental platform, the particle size characteristics and nozzle applicability of the dust samples at the tunnel blasting site are analyzed. Moreover, a computational fluid dynamics software is used to simulate different nozzle layout schemes and incident angles, and the variation laws of concentration, velocity, and particle size in the droplet field are analyzed. Furthermore, the dust removal performance of the new spray system is tested through a field application. The obtained results are as follows: (1) The peak volume frequency of dust along the tunnel moves toward the direction of particle size reduction, and the peak volume frequency increases continuously. (2) The wideangle solid conical nozzle with a 1.9 mm diameter has better dust suppression effect on the dust near the face, and the fine solid conical nozzle with a 1.2 mm diameter has better dust suppression effect on small particle size dust. (3) As the incident angle increase, the area with dust concentrations exceeding 1 g/m3 in the direct incident area of droplets first increases and then decreases. (4) When the nozzle is placed at the top, side, and bottom, the optimal incident angles are 60°, 60°, and 45°, respectively. The field application shows that the dust removal rates of respiration dust and all dusts at each measuring point all exceed 75%. Compared with the original dust control measures, the average dust removal rate of the threesection spray system is increased by 42.71% and can effectively improve the working environment of the construction personnel in the tunnel and prevent outward diffusion of dust in the tunnel.

Key words: tunnel, dust, threesection spray system, computational fluid dynamics simulation, field measurement