Experimental study on hazardous gases and dust removal under forced ventilation in inclined construction tunnels after blasting

Abstract

Pollutant control during tunnel construction differs from that during operation due to the presence of one closed end. Tunnel construction blasting generates significant amount of pollutant gases and inhalable particulate matter, posing health and safety risks to workers. This study performed reduced-scale experiments to investigate the transport of pollutants under forced ventilation after blasting. 1:15 scaled model experiments were performed with emphasis on the effects of inclination and ventilation air volume. The pollutant removal efficiency was assessed based on pollutant removal time, local time-weighted average concentration, and the areal time-weighted average concentration. The results show that ventilation air velocity should be selected according to inclination. Positive tunnel inclinations may cause secondary recirculation of pollutants. The pollutant removal time decreases with increasing air velocity and decreasing inclinations from 5° to −5°. The local time-weighted average concentration of pollutants is significantly higher under positive inclinations than under negative inclinations. The areal time-weighted average concentration of CO is primarily influenced by inclination. For PM2.5, although inclination has a greater impact, ventilation air volume also contributes to its variation. The correlations of dimensionless pollutant removal time with inclination and ventilation air volume were proposed for negative and positive inclinations, respectively. PM2.5 has a longer removal time than CO. These findings provide guidance on pollutant control and ventilation system design under forced ventilation in tunnel construction after blasting.