Investigation of dust pollution control rules in tunnel excavation based on modularized airflow diverging system

摘要

Aiming at addressing serious dust pollution problems in the site environment of tunnel excavation, this study established a computational fluid dynamics (CFD) model to reflect the airflow-dust coupling diffusion behavior in the tunnel, and validated the effectiveness of this model via field measurements. Then, the airflow-dust coupling diffusion results using the modularized airflow diverging system under different conditions were simulated. The results showed that the airflow field can be divided into the "rotating vortex area", the "effective air curtain area", and two "wall attachment effect areas". As the blowing-to-exhaust airflow rate ratio r increased from 0.5 to 1.75, the dust diffusion distance Ld increased gradually from 8.17 m to 17.16 m. With the increase in the distance d between the heading face and the axial airflow outlet, Ld first increased, then dropped, and finally increased. The optimal dust pollution control strategy was determined as when r = 0.75, d = 18 m is regarded as the ending of a section of tunnel excavation, and then a new modularized air curtain generator should be connected. Under the optimal strategy, the weighted average dust exposure concentration around the driver was below 7 mg/m3, dust pollution was completely controlled in the range of approximately 0-9 m away from the heading face, and the environment in the rear of the tunnel was kept clean. Finally, the simulation results were validated via experiments. This study can provide theoretical guidance for the application of the modularized airflow diverging system and the improvement of the environment in the tunnel.