• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.2
• /
• pp.234-242
• /
• 1999

Flow phenomena such as the pressure transients Inside a high-speed railway tunnel and the Impulsive waves at the exit of the tunnel are closely associated with the characteristics of the entry compression wave, which is generated by a train entering the tunnel. Tunnel entrance hood may be an effective means for alleviating the Impulsive waves and pressure transients. The objective of the current work is to explore the effects of the train nose shape and the entrance hood on the characteristics of the entry compression wave. Numerical calculations using the method of characteristics were applied to one-dimensional, unsteady, compressible flow field with respect to high-speed railway/tunnel systems. Two types of the entrance hoods and various train nose shapes were employed to reveal their influences on the entry compression wave for a wide range of train speeds. The results showed that the entry compression wave length increases as the train nose becomes longer and the train speed becomes lower. The entry compression wave length in the tunnel with hood becomes longer than that of no hood. Maximum pressure gradient in the compression wavefront reduces by the entrance hood. The results of the current work provide useful data for the design of tunnel entrance hood.

• Nuclear Engineering and Technology
• /
• v.44 no.6
• /
• pp.639-652
• /
• 2012

A three-dimensional discrete fracture network model was developed in order to simulate the hydraulic characteristics of a granitic rock mass at Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The model used a three-dimensional discrete fracture network (DFN), assuming a correlation between the length and aperture of the fractures, and a trapezoid flow path in the fractures. These assumptions that previous studies have not considered could make the developed model more practical and reasonable. The geologic and hydraulic data of the fractures were obtained in the rock mass at the KURT. Then, these data were applied to the developed fracture discrete network model. The model was applied in estimating the representative elementary volume (REV), the equivalent hydraulic conductivity tensors, and the amount of groundwater inflow into the tunnel. The developed discrete fracture network model can determine the REV size for the rock mass with respect to the hydraulic behavior and estimate the groundwater flow into the tunnel at the KURT. Therefore, the assumptions that the fracture length is correlated to the fracture aperture and the flow in a fracture occurs in a trapezoid shape appear to be effective in the DFN analysis used to estimate the hydraulic behavior of the fractured rock mass.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.2 no.2
• /
• pp.22-31
• /
• 2000

This study aimed at investigating the influence of tunnel length and area, drag coefficient, train velocity on the characteristics of ventilation in railway tunnel. The modified Subway Environment Simulation(SES) computer program has been used to calculate the flow velocity and longitudinal emission concentration with various condition. According to a series of numerical simulation, the influence of various parameter on maximum air flow velocity, purging length and emission concentration are estimated.

• Journal of Industrial Technology
• /
• v.23 no.A
• /
• pp.9-13
• /
• 2003

Numerical experiments are done by a commercial code, PHOENICS to evaluate the backlayer phenomenon of smoke in case of the road tunnel fire. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and ${\kappa}-{\varepsilon}$ turbulence model are 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 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 safely from the polluted region by smoke. These phenomena come from the vertical stratification of the smoke air mixture in the tunnel.

• Journal of Digital Convergence
• /
• v.19 no.12
• /
• pp.457-462
• /
• 2021

As South Korea is a mountainous topography, installation of tunnel is essential for construction of expressway in straight lines. According to "2019 Road Bridge and Tunnel Status Report", there are 2,682 tunnels in Korea with total length of 2,077km. Tunnels take up 1.9% of total road length and the number of tunnel increased by 94% with 1,300 newly constructed tunnels over the 10 years. According to domestic and foreign researches, a long tunnel over 1km in expressway has dark lightings and monotonous wall design which decrease driver's concentration and make the driver feel bored. This leads to feeling fatigue and drowsiness more easily. In response, Korea Expressway Corporation installed design lighting that increases attentiveness on 10 tunnels with total length over 3km by 2020. To reduce the risks of accident that may happen inside the tunnel, this study conducted a comparative analysis on characteristics of each type of LED landscape lighting installed inside the expressway tunnel. The study aimed on providing the basic material for effective installation of LED landscape lighting for securing driving stability, reducing fatigue, and lowering the risk of drowsiness.

• Fire Science and Engineering
• /
• v.30 no.5
• /
• pp.9-17
• /
• 2016

In the case of a medium length road tunnel, the installation of a smoke control facility is not mandatory so users can suffer considerable injuries if a fire breaks out. Therefore, this study analyzed the high-temperature air and toxic gas generated by fire proliferating with time when a smoke barrier is not installed and when the installation interval is 100, 150, 200, and 250 m through 3-dimensional numerical analysis, evacuation simulation, and Quantitative Risk Assessment Methodology targeting the medium length road tunnel. As a result, the diffusion of the high-temperature air and toxic gas occurring from the a fire was delayed when the smoke barrier was installed in a medium length road tunnel compared to that when it was not installed. In addition, when the installation interval of a smoke barrier was 100m and the numerical analysis target was 100m, the diffusion of high-temperature air and toxic gas generated by the fire was delayed more than in the other cases, which was most suitable for tunnel users to evacuate.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.1
• /
• pp.203-211
• /
• 2014

Tunnel reduces travel time as and it is essential facilities for the eco-friendly road construction. In recent years, It has been accelerating the tunnel construction to provide a higher level of traffic service but a driver driving in the narrow and dark tunnel takes characteristically psychological anxiety and the restriction of the sight. Moreover, A driver passing through more than 1,000m long tunnel, as to pass inside the monotonous form of the tunnel for a long time can cause drowsiness and increase the driver load. This driver load can degrade road-holding of the inside of the long tunnel highly and pose a high risk of accidents. Accordingly, In this study is to present the proper length of the Tunnel, considering the characteristics of traffic accident. For this, this study is that the long tunnel that affects traffic safety traffic safety variables are selected and classified. Traffic safety variables are classified in detail as a variable of the traffic accident and velocity one, the applicable variables the number of the traffic accident, the ratio of the traffic accident, driving velocity, the individual vehicle velocity etc. Traffic safety variables are categorized as more than a pole length of the tunnel in order to examine its impact on correlation analysis. The results indicate significant results in traffic accidents in accordance with traffic accidents, traffic safety, selects the variable was Variable depending on the length of the tunnel traffic safety point of significantly increasing the possibility of an accident can be seen as a high point. And the point of the Distribution of selected variables in order to create a traffic safety was a significant increase in traffic safety variables was set at critical intervals. Before reaching the critical point and the corresponding length of the long tunnel was set at the proper length. In this study, the optimum length of the proposed long tunnel through the long tunnel that occur in the future to contribute to reducing traffic accidents would be able to be determined.

• 한국전기화학회:학술대회논문집
• /
• 2002.04a
• /
• pp.26-26
• /
• 2002

• Journal of the Korean Professional Engineers Association
• /
• v.33 no.1
• /
• pp.68-74
• /
• 2000

Until the first stage of the 1990's years, Korean are not concern so much the facilities of traffic tunnel, because of them are the short length and also the quantity of them are not over the several tens in Korea. But, in latest many tunnels has been constructed and are designed in expressway and local national roads. The government office concerned forecast the numbers of tunnel are increased about 300 until the 2003 years, and then we need more interesting about the facilities of tunnel . In the tunnel, the first above of all important facilities is lighting installations which are required much electric energy and continuing maintenance.

• Journal of Korean Association for Spatial Structures
• /
• v.23 no.1
• /
• pp.25-34
• /
• 2023

This paper presents a computational fluid dynamics (CFD) analysis to investiagate the effect of expansion chamber on overpressure reduction in protective tunnels subjected to detonation of high explosives. A commercial CFD code, Viper::Blast, was used to model the blast waves in a protective tunnel with a length of 160 m, width of 8.9 m and height of 7.2 m. Blast scenarios and simulation matrix were establihsed in consideration of the design parameters of expansion chamber, including the chamber lengths of 6.1 m to 12.1 m, widths of 10.7 m to 97 m, length to width ratios of 0.0 to 5.0, heights of 8.0 m and 14.9 m, and ratios of chamber to tunnel width of 1.2 to 10.9 m. A charge weight of TNT of 1000 kg was used. The mesh sizes of the numerical model of the protective tunnel were determined based on a mesh convergence study. A parametric study based on the simulation matrix was performed using the proposed CFD tunnel model and the optimized shape of expansion chamber of the considered tunnel was then proposed based on the numerical results. Design recommendations for the use of expansion chamber in protective tunnel under blast loads to reduce the internal overpressures were finally provided.