Research on Optimization of Forced Ventilation Parameters for Blasting Construction in Large-Section Tunnels Based on CFD

Large-section tunnels produce a large amount of dust after drill-and-blast construction. If not removed in a timely manner, the dust will seriously endanger workers’ health. For the purpose of enhancing the working conditions within the tunnel during construction, this investigation employs an integrated methodology that combines computational simulations with on-site measurements. Drawing upon the principles of gas–solid two-phase flow theory, the coupled diffusion law of airflow and dust in large-section tunnels is investigated. A two-factor orthogonal experiment combined with economic analysis is employed to determine the optimal ventilation parameters for the forced ventilation system. The findings indicate that, when the initial ventilation configuration is applied, the airflow field is divided into three stages, and dust diffusion is primarily driven by airflow. The average dust concentration in the 1.6 m breathing zone at 600 s post-blasting is measured to be 36.8 mg/m3. While satisfying the ventilation demand stipulated for the tunnel, the optimal ventilation parameters are determined as an outlet air velocity of 18 m/s and a duct-to-face distance of 40 m. Under these conditions, the dust concentration is reduced to 1.5 mg/m3, representing a 95.9% improvement in dust removal efficiency. Additionally, the hourly electricity cost at 18 m/s is USD 4.39 lower than that at 20 m/s. This study provides valuable insights for optimizing forced ventilation parameters in large-section tunnels, significantly reducing pollutant levels while saving costs.