Study on dust pollution characteristics and optimal dust control parameters during tunnel excavation by CFD simulation

Aiming at the difficult problem of dust diffusion pollution in tunnel excavation, an air-dust coupling model was established by Euler-Lagrange method to study the dust migration law under different air conditions and the dust control mechanism in the large eddy was analyzed. The results show that when the air volume ratio is greater than 1.33, the dust diffuses to the rear of the tunnel, but the dust concentration in the manned area remains at a low level. When the air volume ratio is less than 1.0, dust can be effectively controlled in the eddy dust collection area. When the Hmp, the hole area rate of the air volume control board, is 30–60 %, the dust control effect is better, especially when the Hmp is 30–40 %, the swirl air distribution effect can be better. When the air volume ratio is 1.0, the air blowing volume and the air exhaust volume are in the range of 273–600 m3/min, and the dust can be controlled in the eddy dust collection area. Field measurement shows that the maximum relative error of dust concentration in the simulation results is 14.16 %, indicating that the numerical simulation results are basically accurate. The similarity experiment shows that the actual dust diffusion distance corresponding to the tracer fog is 9.6 m, indicating that the technology has a strong dust control effect.