Pollutant diffusion in multiple-face tunnel construction: theoretical analysis and numerical validation

Abstract

As the length of the tunnel continues to increase, it will be common for a single fan to undertake the ventilation of two or more tunnel faces. However, the construction of multiple faces in a single tunnel will lead to a complex construction environment in the tunnel, the mutual interference of ventilation, and difficulty in discharging pollutants. Based on the simultaneous construction of multiple tunnel faces in a single tunnel, this study analyzed the transport law of pollutants. The diffusion laws of carbon monoxide and dust in multiple-face tunnels under different working conditions were obtained by numerical simulation. It was found that when both sides of the tunnel are ventilated at the same time, the airflow in the tunnel is spiral, the vortex zone will appear near both sides of the face, and the vortex and unstable airflow will appear at the intersection with the inclined shaft. The airflow in the non-equal-length tunnel at both sides is more disordered than that in the equal-length tunnel, and there will be a wider range of eddy currents at the intersection. The change of dust diffusion in the non-equal-length tunnel at both sides is not obvious, and the length of the multiple-face tunnel has little effect on dust settlement and diffusion. The research results are of great significance for improving the construction environment of tunnel faces and improving the working conditions of personnel.