Ventilation system arrangement in large cross-section tunnels：a CFD simulation based on direct initial concentration assessment

Abstract

ABSTRACTThe dust removal efficiency is essential for safety protection in tunnels. For the cutting head working in a large cross-section tunnel, the extensive movement of the cutting head and large drift space decrease the accuracy of deduced initial dust concentrations. To ascertain the initial dust concentration, cutting models were employed. Then, computational fluid dynamics (CFD) models were established to study the dust movement regularity. Comparison of the best arrangement of the ventilation system, illustrates that some of the rules governing the layout of the ventilation system in small cross-section tunnels can be used in large cross-section tunnels. The results indicate the best range of a ventilation system for distance from forcing and exhausting outlet to working face and airflow ratio. Finally, the dust concentration in different height was analysed and optimized. The study is meaningful for further research and the rules could applied in other hard rock larger cross-section tunnels.