Relay ventilation system with long air-cabin for extra-long railway tunnel: A case study on pollutant transport characteristics after blasting

• Published in: Tunnelling and underground space technology 2025-03, Vol.157, Article 106281
• Main Authors: Zhang, Heng, Zhao, Yiqi, Zhang, Gang, Tao, Yuchun, Ge, Zhenghui
• Format: Article
• Language: English
• Subjects: Blasting; Construction ventilation; Drilling; Extra-long tunnel; Field test; Numerical simulation; Pollutant transport
• ISSN: 0886-7798
• DOI: 10.1016/j.tust.2024.106281

[Display omitted] In order to solve the problems of large amounts of pollutants, low efficiency of air replacement and serious local concentration of harmful gases in the working space of extra-long railway tunnel, this paper proposed a relay ventilation system for long air cabin of extra-long railway tunnel. Through the analysis of on-site monitoring data and full-size numerical simulation, this paper deeply studies the dynamic transport characteristics of pollutants under the conditions of the relay ventilation system with long air-cabin, reveals the transport characteristics of pollutants such as CO and dust and the blocking effect of lining trolly on dust diffusion. The results indicate that the stability of the airflow field is affected by the longitudinal return air velocity of the tunnel, and the fluctuation range of the airflow field is relatively large within the range of 0.5 m/s ∼ 0.7 m/s, which is not conducive to the discharge of pollutants. In the case of single tunnel and double tunnel tunneling, continuous ventilation for 900 s can meet the requirement of CO allowable concentration in the 200-meter range of the tunnel face; trolley has significant blocking effect on the diffusion of blasting dust. The overall dust reduction rate of the second lining trolley area is about 42 % lower than that of the trolley-free construction area, and the peak dust concentration is increased by 37 %. Compared with the trolley operation section, the dust reduction efficiency of the trolley-free operation section is improved by about 2.5 times.