Experimental investigation of tunnel temperature field and smoke spread under the influence of a slow moving train with a fire in the carriage

• Published in: Tunnelling and underground space technology 2023-01, Vol.131, p.104844, Article 104844
• Main Authors: Zhang, Zhiqiang, Tan, Yinjun, Hong, Runlin, Zhao, Yu, Zhang, Heng, Zhang, Yuchun, Li, Zhisheng
• Format: Article
• Language: English
• Subjects: Fire in the carriage; Heat release rate; Model test; On-fire train; Railway tunnel fire; Smoke spread; Temperature field
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2022.104844

•A series of model tests of slowly moving train with a fire in the carriage was carried out.•The relation between the HRR of fire in a slowly moving carriage and the train speed was revealed.•The temperature variation characteristics in the tunnel under moving fire was obtained.•The driving force and spread rate of the smoke produced by slowly moving on-fire train was clarified. A series of model tests were carried out in a 1/10 reduced-scale single-tunnel double-track railway tunnel model to simulate the fire scenario of the on-fire train moving slowly in the tunnel with speeds less than 20 km/h. The influence of the piston wind generated by the slow moving train on the smoke movement was discussed, the relation between the HRR of the fire source in the carriage and the train speed was analyzed, the temperature variation characteristics of the vault and the smoke diffusion law in the tunnel were studied when the on-fire train was moving slowly. The results show that the piston wind speed increases nonlinearly with the increase of the train speed, but the piston wind speed generated by the slow moving train is no more than 10% of the train speed and the main driving force of smoke diffusion is buoyancy. Moreover, the combustion process of the fire source in the slowly moving carriage can be divided into three stages, the heat release rate of the fire source in the carriage decreases with the increase of train speed in the stable combustion stage. Besides, the temperature rising process of tunnel vault also includes three stages, the maximum temperature rising in the fire control stage accounts for 44.2% of the total temperature rising. The smoke accumulation stage is the main period of temperature rising in the tunnel, the temperature rising accounts for more than 94% of the total temperature rising when the model train speed reaches 0.6 m/s.