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  • 1.
    Guo, Qinghua
    et al.
    RISE Research Institutes of Sweden. Tianjin Fire Research Institute of MEM, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Yan, Zhigou
    Tongji University, China.
    Zhu, Hehua
    Tongji University, China.
    Study on spilled liquid from a continuous leakage in sloped tunnels2022Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 120, artikel-id 104290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study focuses on the behaviors of spilled liquid from a continuously leaked tank in sloped tunnels. Spillage width and area, which impact the potential heat release rates in case of fire, are investigated under different tunnel slopes and leakage flow rates by numerical simulations using interFoam based on the VOF method in the OpenFOAM toolbox following the validation. The simulation results show that the spillage width initially decreases rapidly and then slowly as the tunnel slope increases. Other parameters, including road surface roughness, physical properties of liquid and leakage source height, are also considered. Empirical models for predicting the spillage width and area are established considering both tunnel slope and leakage flow rate. The results may provide guidance for tunnel safety design and drainage system design affiliated with a tank leakage inside a tunnel. © 2021 The Author(s)

  • 2.
    Guo, Qinghua
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil. Tongji University, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Yan, Zhiguo
    Tongji University, China.
    Zhu, Hehua
    Tongji University, China.
    Theoretical and numerical study on mass flow rates of smoke exhausted from short vertical shafts in naturally ventilated urban road tunnel fires2021Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, artikel-id 103782Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study focuses on the mass flow rate of the buoyancy-driven gases exhausted from the shaft in naturally ventilated urban road tunnel fires. Theoretical analyses and numerical simulations are performed. The model to predict the mass flow rate of the incoming smoke exhausted by the nearest shaft is developed by considering that the smoke is exhausted along the four sides of the shaft separately. Based on the heat balance between the incoming smoke exhausted and the total gas flow exhausted, the model to estimate the total mass flow rate exhausted from the shaft (both smoke and entrained air) is also established. Meanwhile, a series of numerical simulation in a naturally ventilated tunnel considering the heat release rate (HRR), the shaft height, shaft length and width, shaft location was carried out. The simulation results show that the shaft height has a limited contribution to the mass flow rate of the incoming smoke exhausted while a larger shaft cross-sectional area shows a favorable performance in exhausting the smoke. Further, the air entrainment into the shaft increases with both the shaft height and shaft cross-sectional area. Comparisons of the mass flow rates of the incoming smoke and the total mass flow rates exhausted between simple calculations and simulations are made, showing that the simple models perform well. Further, it is found that there exist two regimes for the total mass flow rate corresponding to different smoke modes in the shaft (complete plug-holing, plug-holing and without plug-holing), which is caused by the different driven forces in the shaft. The outcomes of this work could provide some guidance for the design of vertical shaft and smoke control in naturally ventilated tunnel in urban area.

  • 3.
    He, Kun
    et al.
    RISE Research Institutes of Sweden. University of Science and Technology of China, China.
    Cheng, Xudong
    University of Science and Technology of China, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Shi, Zhicheng
    University of Science and Technology of China, China.
    Yang, Hui
    University of Science and Technology of China, China.
    Zhang, Heping
    University of Science and Technology of China, China.
    Experimental study on flame characteristics of double fires in a naturally ventilated tunnel: Flame merging, flame tilt angle and flame height2021Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 114, artikel-id 103912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of fire tests was carried out to investigate the diffusion flame characteristics of double fires generated from separated burners in a naturally ventilated tunnel, considering different heat release rates and fire separation distances. The results show that the flame tilt angle, as well as the horizontal projected flame length, first increases with fire separation distance and then remains constant, but the vertical flame length first decreases and then remains constant, which is different from two fires in free spaces where flames do not tilt when the separation distance is relatively long. This difference is caused by the non-dimensional fire induced air flow velocity in the tunnel, which is mainly related to the tunnel cross-section dimensions and burner radius. Three regions can be identified, i.e. flame vertical merging, plume vertical merging and non-merging with flame tilted. The critical flame merging separation distance, estimated by the flame merging probability, is greater than that of two fires in an open environment due to the fire-induced air flows. The merging flame height is lower than that of a single fire with a same heat release rate. A correlation was proposed to estimate flame height of two fires in a tunnel by the modified non-dimensional heat release rate using an air entrainment perimeter as the characteristic length. This work enhances the understanding of diffusion flame behaviors of double fires in naturally ventilated tunnels.

  • 4.
    He, Kun
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet. University of Science and Technology of China, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Cheng, Xudong
    University of Science and Technology of China, China.
    Fire spread among multiple vehicles in tunnels using longitudinal ventilation2023Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 133, artikel-id 104967Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The characteristics of fire spread among multiple vehicles in tunnels using longitudinal ventilation were investigated by analyzing the experimental data from a series of fire tests in a 1:15 scale tunnel. Further, a simple theoretical model for gas temperature in a tunnel with multiple fire sources was proposed and used in analysis of the experimental data. The results showed that, for objects (wood piles) placed at a same separating distance downstream of the fire, the fire spread occurred faster and faster along the tunnel. Validation of the simplified temperature model for multiple fire sources was made against both model and full-scale tunnel fire tests. The model was further used to predict the critical conditions for fire spread to the second and third objects. Comparisons with the test data showed that average excess temperature of 465 K (or an equivalent incident heat flux of 18.7 kW/m2) could be used as the criterion for fire spread, and this was verified further by other model-scale tests and full-scale tests. The results showed that the critical fire spread distance monotonously increases with the heat release rate, and decreases with the tunnel perimeter. For multiple fire sources with equivalent heat release rates, as the separation distance between the first two fire sources increases, the critical fire spread distance from the second fire source to the third fire source decreases, but the total fire spread distance from the first fire source to the third one increases. If the total heat release rate at the site of a downstream fire source is greater than that at the former fire source, the critical fire spread distance becomes longer.

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  • 5.
    He, Kun
    et al.
    University of Science and Technology of China, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Shi, Long
    University of Science and Technology of China, China.
    Cheng, Xudong
    University of Science and Technology of China, China.
    Experimental study on the maximum ceiling gas temperature driven by double fires in a tunnel with natural ventilation2024Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 144, artikel-id 105550Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The maximum gas temperature below the ceiling is an important parameter for tunnel safety. The present study analyzed the characteristics of the maximum excess ceiling gas temperature driven by double fire sources in a naturally ventilated tunnel. A series of small-scale tunnel fire experiments were carried out with different fire separation distances and heat release rates. Theoretical analysis based on the equivalent virtual origin was also performed. The results showed that there exists only one peak gas temperature when the two fire plumes are merged before reaching the ceiling, while two peak gas temperatures can be observed when the two fire plumes are completely separated. The maximum excess gas temperature below the tunnel ceiling gradually decreases with an increasing fire separation distance in the plume merging region (S < Scp). When the fire separation distance increases further (S > Scp), the effect of the fire separation distance on the maximum gas temperature below the ceiling is very limited. Furthermore, a model using an equivalent fire source was proposed to predict the maximum excess gas temperature below the ceiling, considering different plume merging states. The present study contributes to the understanding of the maximum excess gas temperature characteristics of the smoke flow driven by double fires with an equal heat release rate in naturally ventilated tunnels. 

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  • 6.
    Ingason, Haukur
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Lönnermark, Anders
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Li, Ying Zhen
    Model of ventilation flows during large tunnel fires2012Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 30, nr Jul, s. 64-73Artikel i tidskrift (Refereegranskat)
  • 7.
    Jiang, Lei
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Säkerhetsforskning.
    Use of mobile fans during tunnel fires2020Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 106, artikel-id 103618Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Smoke control is a key issue in tunnel fire accidents. While jet fans have been widely used in road tunnels, mobile fans provide a good complement, due to its flexibility to operate, especially if there are no fixed jet fans present. To confirm the feasibility of a mobile fan system, full scale fire tests were conducted in Kalldal tunnel in Sweden, with fire size in the range of 1–2.6 MW and a mobile fan placed at the tunnel portal. In the tests, it takes about 4–5 min to establish full flow in the opposite direction and the final flow velocity can reach 1.5–1.9 m/s. To describe the transient behavior of flow development inside tunnel, a one-dimensional lumped theoretical model has been developed. The model takes into account the pressure losses of external wind, the stack effect of fire and friction losses over tunnel walls and two portals. The model is validated using the data from Kalldal tunnel fire tests. Results show that the model can well predict the initial and final steady state velocity, but underestimates the flow development. The model gives prediction on the safe side.

  • 8. Li, Ying Zhen
    et al.
    Fan, Chuan Gang
    Hefei University of Technology, China.
    Ingason, Haukur
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Lönnermark, Anders
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, skydd (BRs ).
    Ji, Jie
    University of Science and Technology of China, China.
    Effect of cross section and ventilation on heat release rates in tunnel fires2016Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 51, s. 414-423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Model scale fire tests were performed in tunnels with varying tunnel widths and heights in order to study the effect of tunnel cross-section and ventilation velocity on the heat release rate (HRR) for both liquid pool fires and solid fuel fires. The results showed that for well ventilated heptane pool fires, the tunnel width nearly has no influence on the HRR whilst a lower tunnel height clearly increases the HRR. For well ventilated solid fuel fires, the HRR increases by approximately 25% relative to a free burn test but the HRR is not sensitive to either tunnel width, tunnel height or ventilation velocity. For solid fuel fires that were not well ventilated, the HRRs could be less than those in free burn laboratory tests. In the case of ventilation controlled fires the HRRs approximately lie at the same level as for cases with natural ventilation.

  • 9.
    Li, Ying Zhen
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Ingason, Haukur
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Overview of research on fire safety in underground road and railway tunnels2018Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 81, s. 568-589Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the past two decades, the interest in fire safety science of tunnels has significantly increased, mainly due to the rapidly increasing number of tunnels built and the catastrophic tunnel fire incidents occurred. This paper presents an overview of research on fire safety in underground road and railway tunnels from the perspectives of fire safety design. The main focuses are on design fires, structural protection, smoke control and use of water-based fire suppression systems. Besides, some key fire characteristics, including flame length, fire spread, heat flux and smoke stratification, are discussed.

  • 10.
    Rahman, Mashuqur
    et al.
    KTH Royal Institute of Technology, Sweden.
    Håkansson, Ulf
    KTH Royal Institute of Technology, Sweden; Skanska AB, Sweden.
    Wiklund, Johan
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    In-line rheological measurements of cement grouts: Effects of water/cement ratio and hydration2015Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 45, s. 34-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rheological properties of cement based grouts change with water/cement ratio and time, during the course of hydration. For this reason, it is desirable to be able to measure this change continuously, in-line, with a robust instrument during the entire grouting operation in the field.The rheological properties of commonly used cement grouts were determined using the Ultrasound Velocity Profiling combined with the Pressure Difference (UVP. +. PD) method. A non-model approach was used that directly provides the properties, and the results were compared with the properties obtained using the Bingham and Herschel-Bulkley rheological models. The results show that it is possible to determine the rheological properties, as well as variations with concentration and time, with this method.The UVP. +. PD method has been found to be an effective measuring device for velocity profile visualization, volumetric flow determination and the characteristics of the grout pump used.

  • 11.
    Rahman, Mashuqur
    et al.
    KTH Royal Institute of Technology, Sweden.
    Wiklund, Johan
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Kotzé, Reinhardt
    CPUT Cape Peninsula University of Technology, South Africa.
    Håkansson, Ulf
    Skanska AB, Sweden; KTH Royal Institute of Technology, Sweden.
    Yield stress of cement grouts2017Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 61, s. 50-60Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rheology of cement grout is complex due to its thixotropic nature and the presence of a yield stress. Despite the importance of the yield stress for grouting design, no standard methods are yet available to determine the yield stress. Most common methods are based on using conventional rheometers, but the results are subjective due to the measurement techniques, applied shear history and hydration. In this work, measurement of the yield stress of cement grout was performed with different measurement techniques using a conventional rheometer. In addition, in-line measurements using an ultrasound based technique were made in order to visualize the flow profile and perform a direct measurement of the yield stress. Two ranges of yield stress, static and dynamic yield stress, were measured. These results should be used for design purposes depending on the prevailing shear rate. The ultrasound based Flow Viz industrial rheometer was found capable of performing direct in-line measurement of the yield stress and providing a detailed visualization of the velocity profile of cement grout.

  • 12.
    Stripple, Håkan
    et al.
    IVL Swedish Environmental Research Institute, Sweden.
    Boström, Lars
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research.
    Ellison, Tommy
    BESAB, Sweden.
    Ewertson, Cathrine
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Produkt & Kontroll.
    Lund, Peter
    Swedish Transport Administration, Sweden.
    Melander, Robert
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Tillståndsbedömningar.
    Evaluation of two different drainage systems for rock tunnels2016Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 58, s. 40-48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water penetration and dripping in tunnels is almost always a significant problem which is usually solved with the help of a tunnel waterproofing drainage system mounted where drips and leaks are detected. Today's drainage systems are made of foamed polyethene (PE) mats which are covered with shotcrete. These are relatively expensive, complex to install, sensitive to mechanical impact, and often have a much shorter expected lifetime than the tunnel. In this study, a new type of drainage, Rockdrain, was studied and compared with the present drainage system. The systems were evaluated with respect to technical, environmental, and economic aspects. A field test was performed with the Rockdrain system and compared with installation of a traditional system. Laboratory tests were performed on especially the different shotcrete layers used in the Rockdrain system. The environmental evaluation was performed by Life Cycle Assessment (LCA) and the economic evaluation was performed by Life Cycle Cost (LCC) analysis. The results indicate that the Rockdrain system has a good drainage function, is significantly cheaper than the current system, has a longer expected lifetime, is easier to install, and is less sensitive to mechanical impact.

  • 13.
    Yao, Yongzheng
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. University of Science and Technology of China, China.
    Li, Ying Zhen
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Ingason, Haukur
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Cheng, Xudong
    University of Science and Technology of China, China.
    The characteristics of under-ventilated pool fires in both model and medium-scale tunnels2019Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 87, s. 27-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates the characteristics of under-ventilated fires in tunnels. This was done by using both model and medium-scale tunnels. The fuels used were heptane and xylene. The mass loss rates per unit area, ventilation rates from tunnel inlet, flame characteristics, O 2 , CO and CO 2 concentrations, optical densities and heat release rates were measured and recorded. Results show that the fire behaviors in under-ventilated tunnel fires are different from that in well-ventilated fires. In under-ventilated fires, the mass loss rate per unit area is found to decrease during identical periods due to the low oxygen concentration resulting from the low ventilation rate and vitiation, meanwhile the flame size dramatically reduces with a lifted and fluttering flame. This was clearly observed in model-scale tests, but due to limited optical view there was no possibility to observe this in the medium-scale tests. As a result, the ventilation rate approaches the amount required for complete combustion of vaporized fuel. This indicates that the combustion has converted from ventilation-controlled to fuel-controlled. No significant increase in CO production is observed in under-ventilated fires. Besides, the equivalence ratio and combustion efficiency were analyzed in order to judge whether the combustion is fuel-controlled or ventilation-controlled. This study provides new experimental information that contributes to improving the understanding of characteristics of under-ventilated fires in tunnel and can help firefighters to make right judgements and take related protective measures during the rescue processes.

  • 14.
    Yao, Yongzheng
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. University of Science and Technology of China, China.
    Li, Ying Zhen
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Lönnermark, Anders
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Ingason, Haukur
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Cheng, Xudong
    University of Science and Technology of China, China.
    Study of tunnel fires during construction using a model scale tunnel2019Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 89, s. 50-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents a study on the characteristics of tunnel fires during construction. A model-scale tunnel was built and fire tests were conducted. The tunnel consists of an inclined access tunnel and a horizontal main tunnel. The main tunnel has two dead ends (excavation faces) and the only opening is from one side of the access tunnel. Propane gas burner and the fibre board soaked with the heptane were used as fuels. The flame characteristics, O 2 and CO volume fraction and gas temperature were measured and recorded. Two typical characteristics of self-extinguishment and smoke spread were found in the tunnel fires during construction. Results indicate that when a fire occurs in the horizontal main tunnel, the critical equivalence ratio for the occurrence of self-extinguishment is within 0.28–1.38 for the propane gas burner and 1.11–3.6 for the fibre board soaked with heptane. The difference is related to the burning behavior of the different fuels used. The fire location in the horizontal tunnel also has a significant influence on the fire development. A well-ventilated fire at the center of the horizontal tunnel becomes under-ventilated due to vitiation when it is located at the closed end of the horizontal tunnel. Besides, when a fire occurs at the closed end of the horizontal main tunnel, the stratification of smoke is destroyed after hitting the closed end, and then the smoke seems to spread over the entire cross section of the tunnel. The smoke spread velocity is found to be proportional to the ventilation rate. However, when a fire occurs at the closed end of the inclined access tunnel (lower end), the fire does not self-extinguish, even when the ventilation rate is 0 m 3 /s. The corresponding smoke spread velocity is higher than that in the horizontal main tunnel. The outcomes of this study provide new experimental information that contributes to improve the understanding of characteristics of tunnel fires during construction and can help firefighters to make better decisions during the rescue processes.

  • 15.
    Zhao, Shengzhong
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. Chongqing University, China.
    Li, Ying Zhen
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Kumm, Mia
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Ingason, Haukur
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Liu, Fang
    Chongqing University, China.
    Re-direction of smoke flow in inclined tunnel fires2019Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 86, s. 113-127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The re-direction of smoke flow in inclined tunnel fires refers to the phenomenon that the smoke flow direction suddenly changes due to the changes of thermal buoyancy or outside pressure or the activation of fans. This poses special risk for fire rescue services fighting fires in tunnels. Both small-scale tunnel fire tests (28 scenarios) and numerical simulations of full-scale tunnel fires (31 scenarios) were conducted to study this special phenomenon. A one-dimensional model was used to predict the flow velocity in the inclined tunnels, based on two different methods for calculating the mean smoke temperature (Method I and Method II, respectively). Results show that the smoke flow direction could be well predicted by the model with Method II. When the ventilation velocity is relatively large and the flow tends to be one dimensional, both methods produce similar results. Further, the influences of important factors on the re-direction of smoke flows were systematically analyzed. These factors include heat release rate, tunnel slope, tunnel length, friction factor, tunnel cross sectional area and fire source location.

  • 16.
    Zhao, Shengzhong
    et al.
    Shandong Jianzhu University, China.
    Yang, Haoran
    Shandong Jianzhu University, China.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Säkerhet och transport, Brand och Säkerhet.
    Liu, Fang
    Chongqing University, China.
    Theoretical and numerical study on smoke descent during tunnel fires under natural ventilation condition2023Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 142, artikel-id 105414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The smoke stratification and the smoke descent along a tunnel are of the utmost importance for personnel evacuation. The paper investigates the smoke descent along a tunnel during a naturally ventilated tunnel fire. A theoretical model is developed to predict the smoke depth below the ceiling along the tunnel. A series of numerical simulations of full-scale tunnel fires are conducted to compare with the developed model, and some coefficients such as the entrainment coefficient are determined from the simulation results. The concepts of critical moment and critical distance are proposed to characterize the smoke descent along the tunnel. The results show that as the smoke spreads longitudinally, the smoke depth below the tunnel ceiling continuously increases. The temperature decay along the tunnel due to heat losses and air entrainment at the smoke layer interface is considered as the main parameter for the smoke descent. After the vitiated air returns back to the fire source, the smoke stratification in the entire tunnel will be significantly reduced. The smoke layer depth along the tunnel based on the temperature distribution is relatively stable in the process of smoke development, which is not sensitive to the HRR, but influenced by the tunnel width, and this method could only be used before the critical moment. The outcomes of this study could provide references for a better understanding of smoke movement in naturally ventilated tunnels and provide technical guidelines for fire safety designers.

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