Normalized modeling of airflow-respirable dust migration and distribution in drilling construction tunnels with different cross-sections

Abstract

Underground construction mainly relies on drilling work. A large amount of dust generated at the drilling location considerably increases the dust concentration in the worker's breathing area. To explore the distribution of respirable dust during the drilling construction, the virtual point source method was selected and extended to establish the theoretical distribution models for tunnels with curved edge cross-sections, and the assumed parameters in the theoretical models were determined via nonlinear fitting with Euler-Lagrange numerical dust migration field generated by drilling construction. The experimental data and theoretical results agree well based on dimensionless analysis, which verifies the validity of the built models. The respirable dust concentration prediction model curves show that the migration process of dust generated by drilling construction in tunnels encompasses free diffusion section phases, restricted diffusion section phases and full diffusion section phases along the tunnel airway, and the corresponding dimensionless distance ranges are 0–5, 5–20 and beyond 20. For the convenience of engineering application, a dimensionless normalization model is proposed based on the established theoretical models. When the ventilation velocity is between 0.4 m/s and 3 m/s, the recommended values of normalization parameters are 0.80, 0.77 and 1.81, respectively. The abovementioned research results reveal that the established effective theoretical prediction model provides a reliable theoretical basis to gain an in-depth understanding of dust migration behavior during drilling construction.