Numerical simulation of fire in road tunnel. Selection of calculation grid

2021 ◽  
pp. 47-54
Author(s):  
И.А. Болодьян ◽  
С.В. Пузач ◽  
А.С. Барановский
Keyword(s):  
Field Tests ◽  
Field Method ◽  
Research Field ◽  
Computational Grids ◽  
Maximum Temperature ◽  
Road Tunnel ◽  
Road Tunnels ◽  
The Masses ◽  
Control Volumes ◽  
Calculation Grid

Рассматривается вопрос выбора расчетной сетки при моделировании пожара в тоннеле с помощью полевого метода и проводится оценка возможного влияния размеров ячеек сетки, а также граничного условия постоянства давления на результаты расчета. Выполнено моделирование пожара для четырех размеров расчетной сетки. Обоснована возможность применения наиболее грубой из используемых сеток с точки зрения инженерных расчетов, в том числе с оговоркой относительно постановки граничного условия. The issue of fire safety of road tunnels is currently an urgent task. Road tunnels are usually not standard typical facilities, but the unique structures. Therefore, it is necessary to study the influence of various parameters on the development of fire in order to take into account the characteristics of a particular object and make decisions on its effective fire protection. Implementation of field tests in this case is expensive and time-consuming. In this regard, numerical modeling is one of the most effective methods of such research. Field models are the most common and currently used for numerical calculations. These models are based on the numerical solution of the system of conservation equations for small control volumes of the calculation grid. This paper examines the issues of selection the calculation grid when modeling a fire in tunnels using the field method is considered and the possible influence of the size of the grid cells is estimated. The mathematical model used in this work is based on a set of differential equations of hydrodynamics, heat transfer, as well as the equation of conservation of the masses of components. Four computational grids were selected for a horizontal (without slope) model tunnel to determine the optimal cell size. As a result of conducted calculations it was established the following: the size of calculated grid is not fundamental for the initial stage of the fire; the use of smaller grid may be preferable at further development of fire, accompanied by increase of combustion capacity to the maximum; the maximum temperature values, especially in the far sections, are obtained on the coarsest grid. The use of such a grid for estimated engineering calculations can be allowed.

Application of numerical modeling to assess the influence of the longitudinal slope in a road tunnel on the fire hazards spread

2021 ◽  
pp. 31-39
Author(s):  
Иван Ардашевич Болодьян ◽  
Сергей Викторович Пузач ◽  
Алексей Сергеевич Барановский
Keyword(s):  
Numerical Modeling ◽  
Rectangular Cross Section ◽  
Field Tests ◽  
Longitudinal Section ◽  
Field Method ◽  
Road Tunnel ◽  
Fire Hazards ◽  
Longitudinal Slope ◽  
Propagation Pattern ◽  
Determining Factor

Рассмотрено влияние продольного уклона автодорожного тоннеля на распространение в нем опасных факторов пожара при возникновении загорания. Для оценки этого влияния использован полевой метод моделирования. Проведен анализ полученных результатов. Сделан вывод о том, что «классическое» понимание картины пожара, основывающееся на принципе «чем больше уклон тоннеля, тем быстрее происходит блокирование», при определенных условиях может не соответствовать действительности. При этом большое влияние на результат расчетов может оказывать постановка граничного условия постоянства давления. One of the important issues in the design and construction of tunnels is to ensure their fire safety. To take into account the characteristics of a particular object and make decision on its effective fire protection, it is necessary to study the influence of various factors on the dynamics of a possible fire. Conducting field tests in this case is expensive and time-consuming. Therefore, one of the most effective methods in this case is numerical modeling. In this paper there is considered the issue of the influence of the longitudinal slope value of a road tunnel on the dangerous factors spread in case of fire. The assessment was carried out by simulating a fire in a model tunnel using the field method. A model tunnel of rectangular cross-section was chosen for conducting numerical experiments. The SOFIE software package was used to implement the model. To evaluate the results obtained there were created the fields of optical smoke density in the central longitudinal section at various time points. This dangerous fire factor is the determining factor because it reaches critical values most quickly. As a result of calculations in the work there was established the influence of the tunnel slope value on the fire hazards spread. It is found that the nature of fire hazards spread in a tunnel without a slope significantly differs from their propagation pattern in an inclined tunnel. If there is a slope, the blocking of tunnel sections (escape routes) up the slope during the first minutes of fire occurs much faster than down, so it is preferable to evacuate people in case of an emergency down the slope. Under certain conditions the principle “the greater the slope of the tunnel, the faster the blocking occurs” can be untrue. At the same time, the obtained result depends on the setting of the boundary condition of pressure constancy during the calculation and can differ from the real fire performance, however, in general, it is not an underestimation of fire danger and can be used in engineering calculations.

scholarly journals Should We Expect a Disastrous Fire Accident in an Urban Road Tunnel? Literature Data Review and a Case Study for Selected Tunnels in Poland

2021 ◽  
Vol 13 (11) ◽  
pp. 6172
Author(s):  
Krystian Szewczyński ◽  
Aleksander Król ◽  
Małgorzata Król
Keyword(s):  
Time Horizon ◽  
Road Traffic ◽  
Traffic Intensity ◽  
Road Tunnel ◽  
Urban Road ◽  
Road Tunnels ◽  
High Uncertainty ◽  
Fire Outbreak ◽  
Fire Accident

Urban road tunnels are a reasonable remedy for inconvenience due to congested road traffic. However, they bring specific threats, especially those related to the possibility of fire outbreak. This work is a case study for selected urban road tunnels. Considering tunnel specificity, road traffic intensity, and structure and based on the literature data for vehicle fire probability, the chances of a fire accident were estimated for selected tunnels in Poland. It was shown that low power tunnel fires could be expected in the 10–20-year time horizon. Although such threats cannot be disregarded, tunnel systems are designed to cope with them. The chances of a disastrous fire accident were estimated as well. Such events can occur when an HGV with flammable goods or a tanker are involved. Such accidents are fortunately very rare, but, on the other hand, that is the reason why the available data are scanty and burdened with high uncertainty. Therefore, a discussion on the reliability of the obtained results is also provided.

Current Safety Issues in Road Tunnel Construction

2020 ◽  
pp. 263-287
Author(s):  
Miguel Vidueira ◽  
Jiri Pokorny ◽  
Vladimir Vlcek
Keyword(s):  
Tunnel Construction ◽  
Road Tunnel ◽  
Significant Safety ◽  
Safety Devices ◽  
Safety Issues ◽  
Safety Standards ◽  
Longitudinal Ventilation ◽  
Road Tunnels ◽  
The Future ◽  
The Subject

The construction of road tunnels is an important part of road infrastructure. The operation of road tunnels has historically been accompanied by a number of extraordinary events. Fires are among the most dangerous ones. Individual countries create their own safety standards that mutually differ to a large extent. Some of the differences of the requirements for safety devices, including the requirements for their functionality, are compared and commented on in this chapter. Moreover, attention is paid to the use of asphalt surfaces on roads and sidewalks in tunnels. This chapter also describes the approach to fire ventilation in tunnels, one of the most significant safety devices. Special attention is paid to the choice of the strategy of longitudinal ventilation, which has been the subject of many discussions. This chapter outlines the possible directions for a solution in the future.

scholarly journals Measurements and fire simulation models in road tunnels

2018 ◽  
Vol 196 ◽  
pp. 04077 ◽  
Author(s):  
Peter Danišovič ◽  
Juraj Šrámek ◽  
Michal Hodoň ◽  
Ján Glasa ◽  
Peter Weisenpacher ◽  
...  
Keyword(s):  
Ventilation System ◽  
Simulation Models ◽  
Project Schedule ◽  
Road Tunnel ◽  
Safety Equipment ◽  
In Situ Experiment ◽  
Emergency Event ◽  
Road Tunnels ◽  
Tunnel Safety

Ventilation system of road tunnel is one of the most important parts of the tunnel safety equipment, especially in view of the emergency event in the tunnel with fire. Last year we presented the testing and the first in situ measurements of our project entitled “Models of formation and spread of fire to increase safety of road tunnels”. With regard to our project schedule we performed also the second in situ experiment. Other part of this paper deals with computer simulations of fires of a selected Slovak road tunnel.

scholarly journals Field Tests on the Attenuation Characteristics of the Blast Air Waves in a Long Road Tunnel: A Case Study

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Yong Fang ◽  
Yi-Lun Zou ◽  
Jian Zhou ◽  
Zhi-gang Yao ◽  
Shuai Lei ◽  
...  
Keyword(s):  
Field Tests ◽  
Blast Waves ◽  
Original Equation ◽  
Road Tunnel ◽  
Highway Tunnel ◽  
Attenuation Characteristics ◽  
Modified Equation

After an explosion occurs in a tunnel, the blast waves take on diverse forms of attenuation in different regions when it propagates along the tunnel. However, the prediction of the overpressure decay laws proposed in previous studies has not taken into account the influence of the different regions in the tunnel. The present paper uses the example of the Micangshan highway tunnel in China and considers many factors that influence the propagation of the blast waves by dividing the tunnel into four zones. The paper modifies the decay equation proposed by Smith and applies it to the Micangshan highway tunnel in China. The decay equations are different in different zones. Field tests in this tunnel show that the modified equation is more suitable to describe the attenuation of the blast waves in the tunnel than the original equation.

Deterministic Risk Methodology for Road Tunnels

2008 ◽  
Author(s):  
Peter Vidmar ◽  
Stojan Petelin
Keyword(s):  
Safety Assessment ◽  
Calculated Data ◽  
Assessment Process ◽  
Strong Impact ◽  
Road Tunnel ◽  
Risk Matrix ◽  
Tunnel Length ◽  
Fire Dynamics ◽  
Road Tunnels ◽  
Ventilation Conditions

The definition of the deterministic approach in safety analyses arises from the need to understand the conditions that emerge during a fire accident in a road tunnel. The key factor of the tunnel operations during the fire is the ventilation, which during the initial phases of the fire have a strong impact on the evacuation of people and later on the access of the intervention units in the tunnel. The paper presents the use of the CFD model in the tunnel safety assessment process. The set-up of the initial and boundary conditions and the requirement for grid density found from validation tests of an FDS (Fire Dynamics Simulator) is used to prepare three kinds of fire scenarios, 20MW, 50MW and 100MW, with different ventilation conditions; natural, semi transverse, transverse and longitudinal ventilation. The observed variables, soot density and temperature, are presented in minutes time steps through the entire tunnel length. Comparing the obtained data in a table allows the analyses of the ventilation conditions for different heat releases from fires. The second step is to add additional criteria of human behaviour inside the tunnel (evacuation) and human resistance to the elevated gas concentrations and temperature. What comes out is a fully deterministic risk matrix that is based on the calculated data where the risk is ranged on five levels, from the lowest to a very dangerous level. The deterministic risk matrix represents the alternative to a probabilistic safety assessment methodology, wherein the fire risk is represented in detail and the CFD (Computational Fluid Dynamics) model results are physically correct.

scholarly journals Study on Securing Safety Based on Emergency Power Dualization inside Road Tunnel

2020 ◽  
Vol 20 (1) ◽  
pp. 217-221
Author(s):  
Jaeyoung Kim ◽  
Sehong Min
Keyword(s):  
Large City ◽  
Pilot Project ◽  
Road Tunnel ◽  
Safety Control ◽  
The Road ◽  
Road Tunnels ◽  
Improvement Measures ◽  
Emergency Power ◽  
Under Construction ◽  
Development Movement

With continued economic development, movement and logistics to various parts of the country are increasing. Consequently, long tunnels in the mountains and the large city underground road tunnels under construction have become increasingly important. Further, the escalating number of road tunnels has resulted in the deepening of tunnels and an increase in the number of long tunnels. Because it is highly possible fora traffic accident inside a tunnel to cause further accidents, various safety improvement measures should be prepared. To resolve the problem, dualizing the emergency power of CCTVs (which perform the major functions of tunnel safety) is proposed for application in a plan to improve safety. This plan improves safety control inside the tunnel and contributes to its maintenance. This study was prompted by the expressway tunnel accidents that occurred in the Central Region Expressway in October 2015 and February 2016. The safety security system based on the dualization of the emergency power inside the road tunnel is being monitored, with its application in some tunnels as the pilot project of an actual lab concept. Moreover, measures on safety control inside the road tunnel can be prepared through the monitoring.

scholarly journals Fire resistance of concrete lining in road tunnels

2021 ◽  
Author(s):  
Meri Cvetkovska ◽  
Zlatko Slavoljub Zafirovski ◽  
Marijana Lazarevska ◽  
Ana Trombeva Gavriloska
Keyword(s):  
Fire Resistance ◽  
Numerical Procedure ◽  
Fire Risk ◽  
Concrete Lining ◽  
Road Tunnel ◽  
Road Tunnels ◽  
Tunnel Design ◽  
Fire Curve ◽  
The Impact

Fire is an incidental load on structures. Experience has shown that in the event of a fire, extremely high temperatures are developed, as a result of which very often a colapse of the tunnel bearing structure happens, usually caused by spalling of concrete. Road tunnel fires are usually caused by vehicles using the tunnel, but can also be caused by exidants, technical breakdowns in tunnel equipment or improper tunnel maintenance. The intensity and frequency of fires in the tunnels are function of several factors such as: length and geometry of the tunnel, density and type of traffic, vehicle speed, slope, availability of ventilation equipment and so on. All of these factors define the fire risk. Based on the defined fire risk, known fire load and location of the fire, it is possible to define the fire curve that defines the temperature in the tunnel versus time. Several fire curves, usually used in EU countries, will be described in this paper, the fire curves characteristics will be defined and the most proper fire curve for typical tunnel, as case study, will be recomended. In the framework of this paper, a methodology for fire resistance analysis of road tunnels, based on the performance, is elaborated. A numerical procedure for defining the behavior of the tunnel lining in case of nominal fire curve (standard fire) is described and applied on one case study. The impact of the fire on the stress-strain state of the concrete structure of a tunnel is analyzed and measures for proper tunnel design in terms of increasing the fire resistance is proposed.

scholarly journals Study on Underground Utility Tunnel Fire Characteristics under Sealing and Ventilation Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Hongtao Zhang ◽  
Yufei Zhao
Keyword(s):  
Safety Evaluation ◽  
Maximum Temperature ◽  
Physical Parameters ◽  
Road Tunnel ◽  
Tunnel Fire ◽  
Ceiling Temperature ◽  
Ventilation Modes ◽  
Utility Tunnel ◽  
Fire Characteristics ◽  
Ventilation Conditions

With the development of the underground utility tunnel in China, the safety evaluation during facility operation inside tunnels is increasingly important after construction. In contrast to fixed fire source in the traffic tunnel, the fire characteristics of the electric cable compartment of the utility tunnel with different ventilation modes are studied. Firstly, the thermal physical parameters of cable material are determined by experiment and numerical simulation. Different fire sealing and ventilation conditions are established according to the practical utility tunnel engineering in FDS. The maximum temperature and smoke gas concentrations are obtained, as well as the heat release rate. The results show that the utility tunnel fire has obvious differences compared with road tunnel fire, where the maximum ceiling temperature and the distributions of smoke is related to fire sealing and ventilation mode. Some suggestions related to evaluation and firefighting are provided for practical purposes.

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