Three-stage numerical simulation of tunnel blasting dust diffusion based on field monitoring and CFD

To further investigate the production and diffusion laws of tunnel blasting dust, this study utilizes a railway tunnel for field measurements and numerical simulations. On-site dust levels are monitored every 10 s using a dust meter. A one-dimensional uniform turbulent diffusion theory is applied to formulate a relationship between dust concentration and space–time variables. The Origin software is employed to fit the on-site dust concentration data. The mass of the tunnel blasting dust at the measurement point is determined using the fitting formula. Characteristics of the blasting dust from the tunnel's surrounding rock are obtained from the on-site analysis of particle size and composition. Employing on-site dust monitoring data and dust characteristics, a three-stage(shock wave generation, pre-ventilation, and post-ventilation) numerical simulation is conducted. On-site monitoring of dust concentrations revealed a characteristic 'M'-shaped temporal profile at the measurement point, and the peak dust concentration reached approximately 2100 mg/m3. Numerical inversion analysis of the three-stage dust diffusion revealed the total dust mass during tunnel blasting to be approximately 178.1 kg. Numerical simulations further indicated that particles measuring below 10 μm were predominantly dispersed throughout the tunnel after 1800 s. This investigation offers a methodology for calculating the total mass of tunnel blasting dust and for its numerical simulation, providing a data reference for dust mitigation strategies.