• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.345-356
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• 2004

Open-cut method has been widely used to construct underground structures, but it causes several problems such as traffic congestion and public resentment resulting from severe construction noise and ground settlement. In many cases, it is very difficult to build underground structures safely due to the unknown locations of buried facilities such as water pipes, drainage pipes, gas pipes and high-pressure cable conduits etc. Also in open-cut method, moving buried facilities causes additional cost and extension of construction period. Therefore, this paper is to present a case study in which Tubular Roof construction Method (T.R.c.M.), a newly developed construction method for underground structures using slab steel pipes and PC wall trench, is applied for the construction of a subway tunnel in Seoul. As a result, it is found that T.R.c.M. is a construction method by which tunnels can be constructed safely without any effect on the surrounding environment and traffic flow due to the minimized construction vibration and noise.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1486-1491
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• 2010

Recently, the frequency and magnitude of the earthquake have increased. The structural safety of the public facilities such as bridges and tunnels etc. which were not concerned for earthquake resistant design are increased. Fiber reinforcement polymer that has been frequently studied for seismic retrofit has advantage as seismic reinforcement material, but it has disadvantage of the brittleness. Therefore, the investigation of safety and seismic reinforcement are required. In this study, new FRP-ductile material layered composites proposed to seismic performance reinforced of subway tunnel. Tensile test of FRP-ductile material layered composites showed that Maximum tensile force of FRP-ductile using Aluminum is similar to existing FRP reinforcement material and maximum strain was increased. In case of application of domestic subway tunnel which need ductility, layered composites of FRP-Aluminum is estimated effectively for increase of seismic performance.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.425-438
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• 2019

A scaled model test was performed to evaluate the stability of subway twin tunnels excavated in the sedimentary rocks with subhorizontal bedding planes. The size of studied tunnel was 6.2 m×6.8 m and pillar width was 4 m. The anisotropic model test specimen was manufactured with the modeling materials suitable for in-situ rocks by way of dimensional analysis. Fracture and deformation behaviors of tunnels according to applied loads were investigated through the biaxial compression test. As the load was increased on the model specimen, the first crack occurred in the middle part of the pillar across twin tunnels and the gradual fractures progressed at crown and floor of twin tunnels. All the cracks in pillar were generated along the existing bedding planes so that they were found to be the main cause of the pillar failure. In addition, the test results were verified by numerical analysis on the experimental conditions using FLAC ubiquitous joint model. The distribution of plastic regions obtained from numerical analysis were in general agreement with test results, confirming the reliability of the scaled model test conducted in this study.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.380-385
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• 2006

In this paper, a program that can be utilized to measure and analyze radio propagation characteristics is developed. This program is able to control the measurement instruments including spectrum analyzer through GPIB interface and analyze the measured data to yield mean excess delay and RMS delay spread. The measured path loss can be compared with theoretical value in free space or inside a tunnel. The measured and analyzed results can also be presented in the forms of graphs. As these tasks can be conducted on the spot of the measurements, this program is very helpful in performing and verifying the measurements immediately. In this thesis radio propagation characteristics with frequency bands of 2.45 and 5.8GHz in subway tunnels are measured by using the program. Path loss and delay spread in subway tunnel is measured and compared according to the form of antenna beam and LOS(Line of Sight) and N-LOS(Non-Line of Sight).

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.1
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• pp.33-47
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• 2015

Concrete lining in tunnel construction is used as secondary support for downward loads when primary support decays. The use of concrete lining varies greatly depending on the intentions of engineer and/or client. An engineer uses much smaller deformation modulus which determines the concrete lining thickness than of a pattern 3, when supporting patterns 4 and 5 are used in a weathered rock and soil. Considering these conditions, this study intends to suggest optimal construction procedures through a back analysis using a computer program(MIDAS-civil). Cases of Seoul Subway System line${\bigcirc}{\bigcirc}$ zone${\bigcirc}{\bigcirc}$ were selected to be examined for this study. The results show that it is possible to reduce the thickness of concrete lining. When results from this study were applied to Seoul Metropolitan subway construction projects, it is expected to bring economic benefits.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.679-686
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• 2018

A new dust cleaning vehicle is needed to remove fine and ultra-fine particulate matter in subway tunnels. Therefore, the recently developed tunnel cleaning vehicle is equipped with an efficient suction system and cyclone-based prefilter to handle ultra-fine particles. To treat various sizes of particulate matter with an underbody suction system, this paper proposes a cyclone-based prefilter in the suction system and validates the dust removal efficiency through Computational Fluid Dynamics (CFD) analysis using ANSYS FLUENT. Using the created surface and volume mesh, various particle sizes, materials, and fan flow rates, the particles were tracked in the flow with a discrete phase model. As a result, the dust cleaning vehicle at a normal operational speed of 5km/h requires at least a fan flow rate of $1500m^3/min$ and 100mm of suction inlet height from the tunnel track floor. Those suction modules and cyclone-based prefilters in the dust cleaning vehicle reduces the dust accumulation load of the electric precipitator and helps remove the accumulated fine and ultra-fine dust in the subway tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.59-69
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• 2000

Three-dimensional total station system which integrated the instrument with Target Pin and TEMS 3D software developed by SKEC R&D center was applied to a tunnel excavation for monitoring of convergence and crown settlement. The efficiency of the system was proved as the result in the aspects of exact monitoring and prediction of rock conditions ahead of the face. To monitor the behavior of tunnel lining at the maintenance stage, DOCS system was applied to the subway tunnel section. Such many effects as the vibration of sensors, verification of the system efficiency, the effect of test trains operation, the variation of temperature and the effect of high voltage was checked. Thus the management scheme for tunnel maintenance was laid out as a proposal.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.77-81
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• 2010

D&B(Drill & Blast) method in tunnel construction requires accurate and rapid measurement of the ground movement, which is essential for feedback analysis. Case study and adaptability of IT technique for tunnel survey are discussed in this paper. The application of laserscannig and existing light wave instrument method in the field of tunnel construction were reported in several advanced country including Austria and Japan. Survey for the shoulder movements by IT survey method was conducted at a subway construction site and the results were compared to the conventional method. Also, the economic aspects of laserscannig method were analyzed using measured data which were categorized by expenses, frequency, interval and period in the field of construction. Therefore IT survey solution may contribute to execute more economic and safe construction

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.99-118
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• 2018

Recently, the limit state design method in the design of the structure is in global trend, but it is limited to a few structures in Korea. Since the introduction of the limit state design method has recently been attempted for tunnels, which are the main underground structures, it is surely necessary to understand the latest limit state design method. Therefore, based on the recently published AASHTO LRFD Road Tunnel Design and Construction Guide Specification (2017), structural load factors and load combinations were reviewed, and various factors which should be applied for the review of structures have been analyzed. In this study, utility tunnel section and subway tunnel sections used in Korea were analyzed by the limit state design method, and we have analyzed the direction of application of limit state design method through studying the tendency of member force by various influential factors such as ground conditions, load modifier and joint stiffness.

• Fire Science and Engineering
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• v.18 no.2
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• pp.49-56
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• 2004

Today's popular ventilation systems include the combined jet fans and electrostatic precipitation systems or the combined jet fans and vertical shaft system. Tunnels with these two ventilation systems applied have been designed and opened, more and more interest has been put in maintenance of a tunnel after opening. Therefore. it is to become more important to come up with the optimal operation mode and the method for the evaluation of ventilation system. In this study, to evaluate a tunnel ventilation and its economy, a dynamic simulation program was developed which can simulate the unsteady-state tunnel air velocity and concentration of pollutants according to the traffic flow variations and operation condition of a ventilation system. We clarified the effectiveness usage on tunnel ventilation by using it and also we could found the most economical ventilation operation mode by application in real exit tunnel. We obtained that combination of fan system and electrostatic precipitation system was more economical than jet fan priority operation mode.