Optimization of ventilation and dust removal parameters in plateau extra-long tunnel inclined shaft based on orthogonal numerical simulation test method

Ventilation and dust removal system in the inclined shaft of the plateau long tunnel is an important component for ensuring safe excavation. The arrangement of wind tube and the volume of air flow have a significant impact on the movement of dust. In order to address the issues of poor ventilation and severe dust pollution in the inclined shaft of plateau long tunnels, this study establishes a dust generation and transportation model for the face of the inclined shaft based on the determination of dust source parameters and their physicochemical characteristics during the excavation process. The results indicate that the particles are predominantly spherical with an approximate diameter of 4 μm at a magnification of 500 times. The dust in high-altitude inclined shafts exhibits poor wettability, with a hydrophobic tendency during the excavation phase, making a ventilation dust removal scheme appropriate. After determining the physical parameters corresponding to the elevation of the inclined shaft, a series of orthogonal numerical simulations involving 3 factors at 5 levels were conducted. Analysis of range and variance revealed that optimal dust control is achieved when the air duct height is 5.725 m, the distance from the working face is 21 m, and the exit wind speed is 29.71 m/s. Comparative analysis confirmed the rationality of the ventilation dust removal scheme under the optimal combination of ventilation parameters. This provides guidance for engineering and environmental management in similar construction scenarios.