Experimental study of back-layering length and critical velocity in longitudinally ventilated tunnel fire with various rectangular cross-sections

Zhang, Tianhang; Wang, Ganyu; Li, Jiangdong; Zhu, Kai; Wu, Ke

doi:10.1016/j.firesaf.2021.103483

Cited by 34 publications

(5 citation statements)

References 28 publications

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“…The heat release rates (HRRs) of 5, 15, and 30 MW are set as numerical simulations of fire sources, corresponding to small cars (5 MW), buses and trucks (15 MW), and heavy trucks (30 MW) starting fires in road tunnels, respectively, to carry out a comparative analysis of fires of different sizes at different lateral fire source locations. In this paper, the model takes the actual tunnel geometry and combines the provisions of the "Design Rules for Road Tunnel Ventilation" JTG/T D70/2-02-2014 and the relevant studies on the critical wind speed of road tunnel fires [29][30][31] : for tunnels with longitudinal ventilation, the critical wind speed is usually in the range of 2.0-3.0 m/s when the fire size is within 30WM, and it increases with the increase of HRR. Therefore, to consider the effect of longitudinal ventilation on the smoke in the tunnel with different fire sizes, seven longitudinal wind speeds, such as 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 m/s, were selected, so that the longitudinal temperature change curves under wind speed variations could be shown in more detail.…”

Section: Model Design and Experimental Conditionsmentioning

confidence: 99%

Study of spatial temperature features of road tunnel fires under multiple factors

Sun,

Yang,

Liang

et al. 2024

Fire and Materials

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After a highway tunnel fire, the rapid change of the internal ambient temperature directly affects the personal safety of pedestrians. Based mainly on the lateral possibility of fire location and considering the coupling effect of multiple factors in a two‐lane highway tunnel, this study systematically carried out 63 full‐size tunnel fire simulation studies relying on Fluent software. The smoke temperature distribution patterns in the transverse and longitudinal spaces of the tunnel after the fire were revealed. This study shows that the smoke temperature below the tunnel vault is susceptible to the effect of sidewall restraint, making the maximum temperature of the tunnel vault of the offset fire source large; considering the lateral location of the fire source, the maximum temperature prediction formula of the tunnel vault is modified to expose the change law of the longitudinal temperature decay of the vault. This paper reveals for the first time the law of temperature distribution changes at the characteristic height of the human eye on the evacuation platform in the tunnel; the systematic study of the fire source cross‐sectional temperature distribution changes at the key lining structure points, and it is found that a low‐temperature space conducive to personnel escape exists in the lower part of the tunnel away from the fire source side. The results of the study are beneficial to the design of safe evacuation paths in the tunnel and the active emergency evacuation of personnel in the near‐fire source area.

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Section: Model Design and Experimental Conditionsmentioning

confidence: 99%

Study of spatial temperature features of road tunnel fires under multiple factors

Sun,

Yang,

Liang

et al. 2024

Fire and Materials

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“…Smoke movement is one of the major phenomena investigated in tunnel fire studies. Zhang et al [57] studied smoke back-layering and critical velocity through numerical analysis and small-scale experimental tests to demonstrate the effect of the tunnel aspect ratio on smoke buoyancy. The importance of smoke dynamics is related to the need for a ventilation system, the characteristics of which must be adapted to the characteristics of fire, such as air velocity, thermal temperature, and smoke stratification [58,59].…”

Section: T12 Smoke Dynamicsmentioning

confidence: 99%

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

Lombardi

Berardi

Galuppi

2023

Fire

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Fire tests are used to determine whether fire protection products meet the minimum performance criteria set out in codes and legislation, as well as to certify these products. Experimental large-scale fires are used to test the performance of safety systems in tunnels, which are confined environments with a high probability of accidents and significant consequences due to the evolution of the event and whether there is the capability of counteracting it by safety measures. In this study, we conducted a systematic literature review following PRISMA guidelines. We searched the Scopus and Web of Science databases for publications from 2013 to 2022, resulting in a selection of 72 articles. An analysis was conducted on the following main topics: tunnel fires, fire characteristics (measured variables, spread, and smoke), model-scale tests, automatic shutdown systems, and ventilation solutions. One of the most important contributions of this study is the suggestion that fire tests represent an effective method not only to prevent fire events in tunnels but also to ensure the resilience of the infrastructure. Based on this state-of-the-art literature review, future tunnels could be designed by linking new smart technology and artificial intelligence to create interactive and high-performing safety systems.

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“…Through fire experiments in a small-scale model tunnel, Li et al (2010) set the value of a to 18.5, the value of b to 0.81, and the value of c to 0.43 without congested vehicles, and the value of a to 13.5, the value of b to 0.63, and the value of c with congested vehicles [13]. The value of c was set to 0.33.…”

Section: Et Al's Empirical Equation Of Backlayering Lengthmentioning

confidence: 99%

“…In view of the above, better understanding of the characteristics of backlayering, especially in conditions of traffic jams, is necessary. Although most research has focused on critical velocity, some studies have investigated the characteristics of backlayering length [6][7][8][9][10][11][12][13]. However, the effect of stranded vehicles has not been taken into account in many of these studies.…”

Section: Introductionmentioning

confidence: 99%

Scale Model Experiments and Simulations to Investigate the Effect of Vehicular Blockage on Backlayering Length in Tunnel Fire

Kawabata

Seike

et al. 2022

Buildings

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This study used model experiments and numerical simulations to investigate the backlayering length of a vehicle-blocked tunnel fire. The experimental setup included two types of obstacles (low obstacles and high obstacles), as well as three configurations: no obstacles, one side with a car obstacle, and two sides with a car obstacle. If there were vehicles on one side of a lane, it would have little effect on the elongation of the backlayer length. When there were vehicles on both sides of a lane, the elongation of the backlayer length was greatly reduced. In addition, the effects of the vehicular blockage ratio and blockage configuration on the properties of the backlayering length were investigated. We created Pattern A, where fire is was in the center, and Pattern B, where fire was on the side of the tunnel. In Pattern A, almost all obstacles could be approximated using the formula. When the vehicle blockage ratio of a single lane was small, an approximation formula for Pattern B was applicable. However, if the distance between stationary vehicles on the upstream side of the fire source was small, the backlayering length could have been longer than in the case with no vehicular blockage.

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Experimental study of back-layering length and critical velocity in longitudinally ventilated tunnel fire with various rectangular cross-sections

Cited by 34 publications

References 28 publications

Study of spatial temperature features of road tunnel fires under multiple factors

Study of spatial temperature features of road tunnel fires under multiple factors

A Critical Review of Fire Tests and Safety Systems in Road Tunnels: Limitations and Open Points

Scale Model Experiments and Simulations to Investigate the Effect of Vehicular Blockage on Backlayering Length in Tunnel Fire

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