Study on Airflow Migration and Rock Dust Pollution Behavior in TBM Construction Tunnel

When tunnel boring machines (TBMs) are used to construct tunnels, large quantities of rock dust are produced, affecting the working environment of construction personnel. To explore ways to improve the air quality in tunnels, this study employed a numerical simulation to investigate controlling rock dust via tunnel ventilation systems. The results showed that when the secondary compressed airflow rate (Q2) was set to 4–11 m3/s, the rock dust produced could be controlled within a range of 77.2 m from the tunnel face. When Q2 = 8 m3/s, the rock dust diffusion distance (LD) reached a minimum of 42.7 m, and the rock dust concentration around the operating region (CW) was approximately 30.1 mg/m3. To explore the further enhancement of dust suppression performance in a tunnel, a numerical simulation was conducted on rock dust diffusion in the tunnel when Q2 was fixed but the exhaust airflow rate (QC) was set to different values. According to the numerical simulation results, when QC = 15 m3/s, the rock dust produced could be effectively controlled at the front of the tunnel with a length of 14.6 m, i.e., the rock dust could be most effectively suppressed.