A Discussion on the Effective Ventilation Distance in Dead-End Tunnels

Manuel García-Díaz, Carlos Sierra, Celia Miguel-González and Bruno Pereiras
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Manuel García-Díaz: Department of Energy, Polytechnic School of Engineering of Gijón, University of Oviedo, 33203 Gijón, Spain
Carlos Sierra: Department of Mining, Topography and Structure Technology, University of León, 24071 León, Spain
Celia Miguel-González: Department of Energy, Polytechnic School of Engineering of Gijón, University of Oviedo, 33203 Gijón, Spain
Bruno Pereiras: Department of Energy, Polytechnic School of Engineering of Gijón, University of Oviedo, 33203 Gijón, Spain

Energies, 2019, vol. 12, issue 17, 1-15

Abstract: Forcing ventilation is the most widely used system to remove noxious gases from a working face during tunnel construction. This system creates a region near the face (dead zone), in which ventilation takes place by natural diffusion, rather than being directly swept by the air current. Despite the extensive use of this system, there is still a lack of parametrical studies discerning the main parameters affecting its formation as well as a correlation indicating their interrelation. With this aim in mind, computational fluid dynamics (CFDs) models were used to define the dead zone based on the airflow field patterns. The formation of counter vortices, which although maintain the movement of air hinder its renewal, allowed us to discuss the old paradigm of defining the dead zone as a very low air velocity zone. Moreover, further simulations using a model of air mixed with NO 2 offered an idea of NO 2 concentrations over time and distance to the face, allowing us to derive at a more realistic equation for the effective distance. The results given here confirm the degree of conservativism of present-day regulations and may assist engineers to improve ventilation efficiency in tunnels by modifying the duct end-to-face distance.

Keywords: ancillary ventilation; effective zone; CFDs; mixture model (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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