• Fire Science and Engineering
• /
• v.17 no.3
• /
• pp.50-54
• /
• 2003

The backlayer phenomena of smoke in the road tunnel is evaluated through numerical experiments. A commercial code, PHOENICS is used to simulate smoke flow in the road tunnel. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and $textsc{k}-\varepsilon$ turbulence model is adopted in the simulation process and mass residual is used as a convergence criterion. The experimental results say that the length of backlayer is reduced linearly with the increase of ventilating air velocity and that there is a critical air velocity which prevents from the onset of backlayering phenomena. One finds that there is a fresh air region near the bottom of tunnel which could make the passenger escape from the region polluted by smoke. These phenomena come from the severe vertical stratification of the smoke air mixture in the tunnel.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.2
• /
• pp.501-511
• /
• 2018

As a result of the recent revision of the 'Guideline for Installation and Management of Fire Prevention Facility in Road Tunnels', the thermal buoyancy has to be taken into account when calculating the capacity of jet fans for smoke control in tunnel fires. However, there is no detailed methodologies for considering thermal buoyancy, so further study is needed. In this study, the thermal buoyancy in the tunnel is calculated by 3-D numerical simulation to consider the thermal buoyancy in case of fire in tunnels, and the relationship between heat buoyancy and vehicle drag, And the method of calculating the capacity of the jet fan for smoke control in tunnels. According to the analysis results, heat buoyancy acts as a resistance force in the case of a down-slope tunnel, and the pressure rise of jet fan for smoke control is not simply determined by the value of heat buoyancy at the entrance of the tunnel and the value of the vehicle drag at the exit. And it is analyzed that it is necessary to carry out a comprehensive review according to the location of the fire vehicle in tunnels.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2002.03a
• /
• pp.19-26
• /
• 2002

서울시에 건설될 새로운 내부 남부순한 도로는 제2 성산대교와 서쪽의 주요 고속화 도로를 연결하는 초고속 도로망을 구축할 것이다. 노선연장은 지하구조물 10.4km를 포함하여 총 34.8km에 달한다. 도로망이 완성되면 수도 서울 중심가의 심한 교통체증은 상당부분 완화 될 것이다. 공사비 7000억원에 이르는 대규모의 서울 남부순환 도로는 3차선 병렬터널 3개 공구를 포함하는 것으로 계획되어졌다. 이들 터널은 3차선, 일방향, 병렬터널로서 계곡부를 관통하며 굴착공법은 대부분 발파공법으로 계획되어져 있다. 가장 긴 관악터널은 지질조건이 복잡하며 따라서, 이런 지반에 적용성이 좋은 발파공법에 의한 굴착으로 계획되어졌다. 특히, 갱구부는 지질상태가 매우 불량하여 풍화암 자연상태로 설계하는 것이 불가능하였다. 설계자들은 터널 화재와 교통사고 등과 같은 터널내에서의 긴급상황에 대한 최적의 대책 수립에 중점을 두어야만 했다. 관악 터널 상부에 위치한 수로관을 통과하는 방법을 찾는 것이 당면 최대 관건이었다. 또한, 갱구부 주변지역의 환경을 보존하고 현장의 자연적인 아름다움 을 유지하기 위하여 굴착량을 최소화하는 공법선정이 중요하였다.

• Fire Science and Engineering
• /
• v.33 no.2
• /
• pp.124-131
• /
• 2019

When a fire occurs in a road tunnel, it is likely to develop into a major disaster because of its sealed structural characteristics. Because of this, a range of disaster prevention facilities should be installed, and they should show their appropriate functions in fire prevention and response. In addition, the installation of essential disaster prevention facilities is missing due to the lack of considering an extension of continuous tunnels and soundproof tunnels. For these reasons, it was judged that an amendment to the law would be necessary. Therefore, this paper reviewed the changes in domestic laws related to the disaster prevention facilities of road tunnels, and the results of the study on the parts that need to be revised in the fire-related laws through a comparative analysis between laws are as follows. First, consecutive tunnels should consider the sum of the extensions of the individual tunnels and ensure that the soundproof tunnels are included in the category of tunnels in the law. In this way, the necessary disaster prevention facilities should be installed. Second, it is necessary to secure a legal justification for installing disaster prevention facilities in tunnels. Therefore, it is essential that water mist fire extinguishing system facilities, emergency broadcasting facilities, and leading lights, which are excluded from installation in tunnels, are specified in the Fire-related laws. Third, to specify in the law that air respirators must be provided in the tunnel is necessary from the viewpoint of the field response. Accordingly, it will make a great contribution to the fire-fighting activities and the life-saving efforts by fire-fighters.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.6 no.4
• /
• pp.269-278
• /
• 2004

Recently, critical velocity has become a topic to attract most interests from the researchers in the field of tunnel safety. As the minimum velocity to prevent smoke backlayering during a fire, many equations have been proposed so far, and the following three equations are being considered as a standard method in Korea to calculate the capacity of smoke extraction fans. Equation by Kennedy based on Froude number, Tetzner' s equation with additional variable, ${\beta}$ to modify the Kennedy's equation, and the equation with the concept of super critical velocity by Wu are studied in this paper for the comparative purpose. A contour map describing the relationship between the critical velocity and the capacity of smoke extraction fans is proposed as a tool to calculate the number of jet fans for smoke control during a fire in the local tunnels.

• Fire Science and Engineering
• /
• v.22 no.3
• /
• pp.201-207
• /
• 2008

In this study, three Dimensional CFD simulations were carried out to investigate the effective smoke extraction system in bi-directional road tunnel fires using FLUENT. Characteristics of transverse system with big size extraction port or with uniform extraction port, semi-transverse system and longitudinal system for smoke extraction system were analyzed. Air velocity, port size, and operating method were used with variable. Distributions of smoke spread, CO was analyzed. As a result, the transverse ventilation system with big size port was found to be more effective than the uniform ports for bi-directional road tunnel.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.4
• /
• pp.411-417
• /
• 2009

The thermo-flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, piston effect is one of primary causes for formation of air flow in road tunnel and has an effect on initial direction of smoke flow in tunnel fire. In this study to analyze the unsteady flow in the tunnel caused by the run of vehicle, the experimental study of vehicle-induced unsteady flow on a reduced-scale model tunnel is presented. While the three types of vehicle shape such as basic type of rectangular shape, diamond-head type and stair-tail type are changed, the pressure and air velocity variations with time are measured. The rising ratio of pressure and velocity are in order of "basic type of rectangular shape > stair-tail type > diamond-head type". The experimental results would be good data for development of a numerical method on the vehicle-induced unsteady tunnel flow.

• Fire Science and Engineering
• /
• v.33 no.1
• /
• pp.85-91
• /
• 2019

This study evaluated the fire detection performance of an automatic fire extinguishing system for road tunnels, which combines flame wavelength detection technology with flame image detection technology. This fusion technique to improve the fire detection capability can reduce the damage caused by the fire suppression by locating the fire source in the fire and discharging the pressurized water only at the fire source. Experiments were conducted to determine the position of a fire source when a $70cm{\times}70cm$ target was placed at a distance of 15 m, 20 m, 25 m, 30 m, and 35 m, respectively, in a situation where there is a flame and smoke in a tunnel. The performance of the ultraviolet and triple wavelength infrared (IR3) sensors was attenuated due to the interference of thick smoke. In addition when the flame was blocked by thick smoke, the image sensor sensed the smoke and emitted a fire signal.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2000.11a
• /
• pp.287-292
• /
• 2000

최근에 각종 SOC사업이 본격화되면서 고속도로망 및 도시교통망 확충이 가속화되어 장대 터널이 급증하고 있을 뿐만 아니라 차량의 급속한 증가로 차량배기가스에 의한 터널내부 환경의 악화가 문제시되고 있다. 특히 도로터널은 반밀폐 공간으로 터널내에서의 사고는 인명피해와 막대한 재산 피해로 이어질 수 있으므로 안전운전을 위한 제반설비 및 대책이 필요하며 안전운행을 위한 가시거리 확보 및 쾌적한 환경에 대한 요구가 대두되고 있다. 따라서 터널에서 이와 같은 요구를 만족하기 위해서 기계환기설비가 투입되고 있으며 이에 대한 최적화 설계에 대한 필요성이 높아지고 있다.(중략)

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.3
• /
• pp.301-310
• /
• 2013

Jet fans are installed in road tunnels in order to maintain critical velocity when fire occurs. Generally the number of jet fans against fire are calculated by considering critical velocity and flow resistance by wall friction, vehicle drag force, thermal buoyance force and natural wind. In domestic case, thermal buoyance force is not considered in estimating the number of jet fans. So, in this study, we investigated the pressure loss due to the thermal buoyance force induced by tunnel air temperature rise and the impact of thermal buoyance force on the number of jet fans by the numerical fire simulation for the tunnel length(500, 750, 1000, 1500, 2000, 3500m) and grade (-1.0, -1.5, -2.0%). Considering the thermal buoyance force, number of jet fans have to be increased. Especially in the case of 100MW of heat release rate, the pressure loss due to thermal buoyance force exceed the maximum pressure loss due to vehicle drag resistance, so it is analyzed that number of 2~11 jet fans are needed additionally than current design criteria. Thus, in case of estimating the number of jet fans, it must be considered of thermal buoyance force induced tunnel air temperature rise by fire.