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  • 1.
    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 fires2012Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 30, nr Jul, s. 64-73Artikkel i tidsskrift (Fagfellevurdert)
  • 2. 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 fires2016Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 51, s. 414-423Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3.
    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 tunnels2018Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 81, s. 568-589Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    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 hydration2015Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 45, s. 34-42Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5.
    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 grouts2017Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 61, s. 50-60Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 6.
    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 tunnels2016Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 58, s. 40-48Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    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 tunnels2019Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 87, s. 27-40Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    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 tunnel2019Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 89, s. 50-67Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    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 fires2019Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 86, s. 113-127Artikkel i tidsskrift (Fagfellevurdert)
    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.

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