• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.25-31
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• 2013

In this study, the total loss and damage ratio of maintenance monitoring which is installed and operated in the domestic and foreign tunnel structure is researched and analyzed for estimating the loss and damage ratio of maintenance monitoring sensor of subway tunnel. The total loss and damage ratio at the elapsed time of 5-6 years after installation is 14.2% in the Seoul metro line no.5,6 and 7, 14.8% in the section 1 of the Seoul metro line no.9, 13.9% in the Channel tunnel of England and all of them are close to 15%. Therefore, it is reasonable to reflect that the total loss and damage ratio of maintenance monitoring sensor of subway tunnel is estimated provisionally 15% on design, and hence the study of the loss and damage ratio with the number of elapsed years in long-term by the measurement category will be needed.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.133-151
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• 1991

In this paper an analytic discussion was made for a finite element analysis performed for the case study of Seoul subway NATM tunnel. The effects mainly discussed on the ground deformation analysis were the staged tunnel excavation and the excavated distance from a tunnel facing. The concept of ground characteristic line has been applied to properly consider the loading condition given by staged tunnel excavation so that the imaginary supporting pressure is applied on the excavated tunnel face. Discussions on the results of the performed finite element analysis were mainly made with respect to the ground settlement, tunnel displacement, earth pressure, stress mobilized in supporting members. And the three dimensional supporting effect due to the tunnel facing was evaluated based on an elastic closed-form solution and a result of two dimensional axisymmetric finite element analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.829-834
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• 2009

Alluvial soil is one of the most difficult grounds for tunneling works due to the insufficient ground strength and excessive ground water inflow. Dduk island in Seoul has a wide alluvium developed by two rivers, Han and Jung-Ryang. Subway tunnel of $\bigcirc\bigcirc$ line planed across Dduk island has highly poor ground conditions due to small cover and deeply developed alluvium. Moreover, much part of this tunnel is located parallel to the bridge foundations of another railway with a small horizontal distance. Original design was done in 2002 and construction has been in progress. During the construction, tunnel design has been partly changed and adjusted for the complex ground condition and the demand from related organizations. This paper intend to introduce the urban tunnel design and construction in alluvial soils. This line could be divided three sections(A, B, C) according to ground and adjacent conditions. Section A is featured by mixed tunnel faces consisted with alluvial soils and weathered or weak rocks. The feature of section B is that tunnel underpasses near the bridge foundations of another subway. Lastly, section C with a very short length is the most difficult construction conditions due to the small cover, poor ground, obstacles on and underneath ground surface.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.31-38
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• 2011

In this study, we investigate simulation studies to confirm the removal of smoke through ventilation when the subway car is on fire and stopped in an underground subway tunnel, by using Fire Dynamics Simulator (FDS) which is being upgraded by NIST. The structure of subway tunnel and train for simulation modeling are based actual data from Seoul metropolitan subway. The main purpose of this study is to assure the removal efficiency of the ventilation when changing the ventilation capacity between 2.0 m/s and 3.0 m/s. The results of the study shows that carbon monoxide (CO) and carbon dioxide ($CO_2$) are reduced by about 35% as the ventilation capacity is increased by 0.5 m/s. This study also performs the grid sensitivity verification of FDS for improved accuracy of the results. To find the effective size of the grid, three cases are simulated and the results are compared.

• Explosives and Blasting
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• v.10 no.2
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• pp.3-7
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• 1992

Concerning to Taeku city subway construction project(1-4 site), the original design was adapted NATM Tunnel method to the 8 meter thickness of overburden. Surveyor checked sity and design material and finally decided to change into Open Cut method because overburden is not only below 1 1/2 times thickness of comparate Tunnel width but there is no traffic conjunction in job site.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.223-230
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• 2008

This paper deals with the measurements of wireless image signal in subway tunnels at 2.45GHz. Measurements have been conducted in 3 subway stations with different types; a straight tunnel and two curved tunnels. As a analysis result for the measured data, we found that the signal level inside straight tunnel by the strong multipath waves fluctuate deeply compared to the curved tunnel. The path loss exponent for the Shin-hung station with the straight tunnel is 2.5, those for the Pan-am and Dae-dong station with curved tunnels are 1.6 and 1.9, respectively. The fade depth and width at 50% point became relatively serious at Shin-hung station, the level crossing rate inside the Pan-am station is larger than the other stations. Therefore, it can be concluded that the fading phenomena affect to the signal performance generate seriously at straight tunnel compared to the curved tunnel.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.100-106
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• 2011

PSD(platform screen door) was completely installed at all of Seoul subway station(line 1~8) using 640million people per day by 2010. After installation of PSD, the influence of train induced wind at platform decreased, but is estimated to increase in subway tunnel. In this paper, train induced wind occurred by pass of subway at platform was measured and analyzed using numerical analysis by computational fluid dynamics.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.303-308
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• 2000

By means of analyzing of monitoring technology and monitoring regulation based on maintenance monitoring system installed in subway tunnel section, it needs monitoring system, development of operating program, monitoring analyzing system and development of analysis method, establishment of maintenance monitoring standard specification, and performance of responsible monitoring supervision for applying to subway monitoring maintenance effectively in future. It requires specialized monitoring and legislation of monitoring subcontract, improvement of monitoring work contract method, establishment the standard payment of monitoring, and effective calibration and correction of monitoring system in the plan of improving monitoring regulation.

• Fire Science and Engineering
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• v.17 no.2
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• pp.62-69
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• 2003

The smoke control system in subway platform is not only using for smoke exhaust facility but also using ventilation system. For this reason, smoke vent effectiveness is depending on its position, ventilating volume capacity and the vent method. In this study, the passenger's evacuation time was calculated for the case of fire on sloped subway train vehicle in subway platform. In order to recommend the mechanical smoke exhaust operation mode, SES (Subway Environmental Simulation) was used to predict the airflow of the inlet and outlet tunnel for the subway station. Fire dynamics Simulator(FDS) was used the SES's velocity boundary conditions to calculate the smoke density and temperature under the condition of fire on stopped subway train vehicle at the platform. We compared smoke density and temperature distributions for each 6 types of smoke exhaust systems to clarify the characteristics of smoke and hot air exhaust effectiveness from the result of fire simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.121-124
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• 2014

Many of research on noise reduction techniques have been progressed for the improvement of noise environment in subway train. There are many way to noise reduction techniques in the tunnel, but it has been reported as an alternative to attach sound absorption material on tunnel wall. For this reason sound absorption material has been studied for application of tunnel. The objective of this study is to investigate design parameters on a Helmholtz resonator with built-in sound absorption panel for the reduction of the tunnel noise in the subway. Sound absorption panel composed of the perforated panel with sub-millimeter holes and the airspace backed a rigid wall or between panels. The experiment is performed through the change of number of perforated panel, cross sectional area and the depth of airspace of the sound absorption panel under the normal incidence sound.