INFLUENCE OF GEOMETRIC PARAMETERS AND VELOCITY OF VENT ON HEAVY GAS EXHAUST EFFICIENCY IN TUNNELS

19th WORLD CONFERENCE OF THE ASSOCIATED RESEARCH CENTRES FOR THE URBAN UNDERGROUND SPACE, Belgrade, Serbia, November 4-7, 2025. (Paper No: 4.12.94,  pp. 765-776)

 

АУТОР(И) / AUTHOR(S): Yuanqing Ma, Tianqi Wang, Ying Zhang, Angui Li

 

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DOI:  10.46793/ACUUS2025.4.12.94

САЖЕТАК / ABSTRACT:

Underground spaces are relatively enclosed, which imposes stringent requirements on ensuring personnel safety and achieving effective removal of harmful gases. Notably, high-density harmful gases (hereafter referred to as „heavy gases“) tend to accumulate in human breathing zones, posing a severe threat of fatalities and injuries. Consequently, research on exhaust strategies to enhance the removal efficiency of heavy gases in tunnels has become an urgent necessity. In this study, a series of computational fluid dynamics (CFD) simulations were conducted to investigate the removal process of heavy gas contaminants in tunnels. Specifically, the effects of three key parameters—namely the aspect ratio (w/h), vent area (A), and vent height (hf)—on the performance of side-mounted exhaust vents for addressing heavy gas leakage in tunnels were systematically analyzed. The results reveal that with the increase in w/h and A, both the height of the heavy gas layer downstream of the vent and the heavy gas density exhibit a decreasing trend. However, excessively large A and hf can lead to the discharge of fresh air through the vents when the exhaust velocity is low, which is detrimental to the overall exhaust efficiency. Within the parameter range investigated in this study, an optimal vent height of 0.1 m was identified. Furthermore, the highest exhaust efficiency of 0.18 was achieved when the vent area was 2 m² and the exhaust velocity was 6 m/s. The findings of this research provide a theoretical and data-driven basis for the optimal design of ventilation systems tailored to heavy gas control, thereby facilitating the effective removal of heavy gases in underground spaces.

КЉУЧНЕ РЕЧИ / KEYWORDS:

Heavy gas; Underground Space; Side exhaust; Exhaust efficiency; Gas leakage

ПРОЈЕКАТ / ACKNOWLEDGEMENT:

The study was supported by Shaanxi Province Technical Innovation Guidance Special Project (No. 2023GXLH-051), Foundation of International Joint Laboratory on Low Carbon Built Environment, Ministry of Education (Xi’an University of Architecture and Technology). The authors are grateful for the support.

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