Metro systems : Construction, operation and impacts

Peer reviewedPublisher PD

An Improved Method for Determining The Interface Height of Smoke Layer in A Tunnel Fire

Smoke layer interface height is an important parameter in fire safety science. In this paper, two methods are proposed on the basis of integral ratio method and the least squares method. a series of experiments were conducted in a 1:10 scale model tunnel for determining the smoke layer interface height in tunnel fire. The interface height of the smoke layer determined by the new methods have been compared with other existing approaches, including integral ratio method, least squares method, N-percentage rule. The comparison results show that the results of the least squares method based on the transition layer can be relatively reasonable and agree well with the visual observations for all experimental condition. In addition, the usage scenarios and considerations of the N-percentage rule were also discussed

Investigation and improvement of indoor air quality in office buildings

Purpose / Context - Improve indoor air quality. Methodology / Approach - Investigate the objectives of the study through subjective questionnaire survey and field test of the selected parameters. Results – According to the practical problems of the office building, the reasonable solution is put forward. Key Findings / Implications – The indoor thermal and humid environment, air quality and thermal comfort of human body were studied and analyzed in order to determine practical strategies for improvement program, aimed at addressing the problems existing in office buildings. Originality - Investigate the office building alone, make a concrete analysis of the factors influencing the quality of indoor air, propose an antidote against the disease of the office environment

Numerical study on the effect of shaft position on natural smoke exhaust in tunnels with one closed portal

.This paper uses Fire Dynamics Simulator (FDS) to study the effect of the longitudinal distance from the shaft to the fire source on the natural smoke exhaust of the tunnel fire with one closed portal, and analyzes the temperature distribution of the smoke and the shaft’s smoke exhaust efficiency. The results show that when the shaft is located downstream of the fire source (Ds0), the smoke exhaust efficiency increases slightly with the increase of the distance from the shaft to the fire source, but the overall value is relatively small. When HRR is fixed, the shaft located downstream of the fire source has a higher smoke exhaust efficiency. As the distance between the shaft and the fire source increases, the plug phenomenon decreases

Effect of the Metro Train on the Smoke Back-Layering Length under Different Tunnel Cross-Sections

Smoke back-layering length is an important aspect of tunnel fire research, and the influence of metro train blockage cannot be ignored. In previous studies, less attention has been paid to the phenomenon of back-layering caused by the same train blocked in tunnels with different cross-sections. This paper investigates this point through dimensionless analysis and fire dynamic simulator (FDS) numerical simulation. Several full-scale model tunnels (300 m in length), with different tunnel cross-sections, were constructed in FDS. According to the FDS simulation result, the smoke back-layering length was compared and analyzed. To investigate the effect of the tunnel cross-sections on smoke back-layering length under metro train blocking, the headroom ratio ε was proposed. Then, the influence of the tunnel cross-section on the smoke back-layering length was discussed in detail. Based on the dimensional analysis and FDS simulation results, a new model for predicting the smoke back-layering length was proposed. The prediction model obtained in this paper was compared with the FDS simulation results and the prediction model proposed by our predecessors. It is proven that the proposed model can better predict the length of smoke back-layering when metro trains are blocked in tunnels with different cross-sections. The outcomes of this work are expected to provide theoretical guidance for fire smoke control in metro tunnels with different cross-sections

Effect of the Metro Train on the Smoke Back-Layering Length under Different Tunnel Cross-Sections

Smoke back-layering length is an important aspect of tunnel fire research, and the influence of metro train blockage cannot be ignored. In previous studies, less attention has been paid to the phenomenon of back-layering caused by the same train blocked in tunnels with different cross-sections. This paper investigates this point through dimensionless analysis and fire dynamic simulator (FDS) numerical simulation. Several full-scale model tunnels (300 m in length), with different tunnel cross-sections, were constructed in FDS. According to the FDS simulation result, the smoke back-layering length was compared and analyzed. To investigate the effect of the tunnel cross-sections on smoke back-layering length under metro train blocking, the headroom ratio ε was proposed. Then, the influence of the tunnel cross-section on the smoke back-layering length was discussed in detail. Based on the dimensional analysis and FDS simulation results, a new model for predicting the smoke back-layering length was proposed. The prediction model obtained in this paper was compared with the FDS simulation results and the prediction model proposed by our predecessors. It is proven that the proposed model can better predict the length of smoke back-layering when metro trains are blocked in tunnels with different cross-sections. The outcomes of this work are expected to provide theoretical guidance for fire smoke control in metro tunnels with different cross-sections