• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.127-134
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• 2021

When constructing a tunnel on a stable ground, stress is changed in the ground during excavation stage and installation of ground support materials. In the standards for safety evaluation of structures in use, it is suggested to perform numerical analysis reflecting the excavation stage. But method of seismic performance evaluation was not presented. Therefore, in this study, numerical analysis was performed with different analysis methods, and the results were compared and analyzed. As a result of the numerical analysis, seismic wave applied in the horizontal direction were no difference depending on the analysis methods. However, there was a big difference in the result according to the evaluation methods of tunnel member forces. When reviewing with the strength design method, the structure performance could be not satisfied depending on the existence or nonexistence of reinforcing bars. Based on these research results, it is suggested that the interpretation method should be clearly presented and reflected in the relevant standards.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.357-367
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• 2006

Recently, as the construction of new railway and the relocation of existing line increase, tunnel structures grow longer. The railway fire accidents in long tunnel bring large damages of human life and disaster. The interest of safety in long tunnel have a growing and the safety standard of long tunnel is tightening. For that reason, at the planning of long tunnel, the optimum design of safety facility in long tunnel for minimizing the risks and satisfying the safety standard is needed. For the reasonable design of long railway tunnel considering high safety, qualitative estimation for tunnel safety is required. In this study, QRA (Quantitative Risk Assessment) technique is applied to design of long railway tunnel for assuring the safety function and estimating the risk of safety. The case study for safety design in long railway tunnel is tarried out to verifying the QRA technique for two railway tunnels. Thus, the inclined and vertical shaft for escape way and safety facilities in long tunnel are planned, and the risks of tunnel safety for each case are estimated quantitatively.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.21-26
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• 2001

Because of the continuous growth of energy consumption, and also tile tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Recently, the results of assessment about a system integrity are needed in korea also when a gas pipeline is running parallel with high voltage power line in same submarine tunnel, Therefore, we analyze the system integrity(AC corrosion of pipe, melting of pipeline coating, safety of insulation flange, especially cathodic protection system which are rectifier and CI(cathodic Isolator)) resulting from the influence of high voltage power system.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.39-48
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• 2003

Previous analytical models for key blocks have been based on the assumption of infinite persistent discontinuities. In this paper, a key block analysis method considering the finite persistence of discontinuities is proposed as a stability evaluation method in tunnel constructions, and then applied to an actual example site. Three-dimensional rock block identification with consideration of the persistence of discontinuities is performed by using discontinuity disk model. The removability and stability analyses of rock blocks formed by the identification method are performed. The identification method can handle convex and concave shape blocks. In order to demonstrate the applicability of this developed numerical method to the stability evaluation in tunnel constructions, the analytical results are examined and compared one another.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.165-173
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• 2016

This paper dealt with contents on the performance evaluation of standardized steel and non-standardized steel of lattice girder. Lattice girder is arch type tunnel supports made of structural steel bar and it is girder used to ensure the stability of tunnel by suppressing any transformation of ground as much as possible during tunnel excavation. The performance evaluation of lattice girder can be conducted through bending strength test, tensile strength test and tunnel standard specification specifies that welding structural steel with over 500MPa yield strength shall be used. However, it is difficult to distinguish visually between standardized steel and non-standardized steel onsite if low-quality structural steel is used. Accordingly, this paper conducted performance evaluation of standardized steel and non-standardized steel of lattice girder to point out the issue of deteriorated yield strength of non-standardized steel, while proposed a method of verifying yield strength onsite.

• Tunnel and Underground Space
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• v.13 no.2
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• pp.138-152
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• 2003

Three-dimensional computer modeling using FLAC3D had been carried out fur evaluating the thermal-mechanical stability of a high-level radioactive waste repository excavated in several hundred deep location. For effective modeling, a FISH program was made and the geological conditions and rock properties achieved from the drilling sites in Kosung and Yusung areas were used. Sensitivity analysis fer the stresses and temperatures from the modeling designed utilizing fractional factorial design was carried out. From the sensitivity analysis, the important design parameters and their interactions could be determined. From this study, it was found that deposition hole spacing is the most important parameter on the thermal and mechanical stability. The second and third most important parameters were disposal tunnel and buffer thickness.

• Tunnel and Underground Space
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• v.20 no.6
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• pp.446-454
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• 2010

CAES-G/T (Compressed Air Energy Storage - Gas Turbine) power generation is a likely option for the buffer facility stabilizing the fluctuation of the renewable powers, such as wind and solar powers. Considering the geological conditions, the underground CAES facility is most probable if the CAES-G/T generation is planed in Korea. In this kind of facility, a concrete plug is installed to seal the compressed air in the container, so that the selection of the shape and dimension of concrete plug could be a critical design factor. The stability evaluation of two types of plug was carried out by investigating the distribution of the factor of safety in the plugs and the distribution of contact pressure over the contact surface. The analysis result shows that the taper-shaped plug is more structurally stable than the wedge-shaped plug for the given geological condition. Possible separation of the rock-concrete interface around the spring line of the wedge-shaped plug is anticipated, which means the possible leakage of compressed air through the side wall and also means the poor mobilization of frictional resistance on that area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.361-369
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• 2008

Control of ground water is one of the most important factors for long-term operation of tunnel because most of tunnel is located in the ground. In case of leakage tunnel, there is no pore water pressure on the lining when the drainage system is properly working. After long-term operation, however, the pore water pressure can be developed on the lining due to the deterioration of the drainage system. The increased pore water pressure on the lining is termed here as 'residual pore water pressure'. Residual pore water pressure can be measured by piezometer, but it is generally not allowed because of damages of drainage system. Therefore, an indirect and nondestructive method is required for evaluating the residual pore water pressure. Moreover, understanding of pore water pressure is needed during healthy operation of the lining. In this study, a new method for evaluation of pore water pressure on the lining during operation is proposed using theoretical and numerical analysis. It is shown that the method is particularly useful for stability investigation of pore water pressure on the lining during operation using theoretical analysis with normalized pore water pressure curve.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.118-122
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• 2010

The study presents a standard time-temperature curve to evaluate the fire performance of subway tunnel structures. The central subway section is 135km long in Korea, the fourth longest in the world. The number of subway tunnels has been increasing rapidly and fire risk is proportional to the tunnel length. However, an adequate time-temperature curve for subway tunnel fires does not exist. Therefore, we studied a proposed foreign fire design model for which the heat rate is based on the traffic, and we present an appropriate time-temperature curve for Korean subway tunnels. The ISO 834 curve was used as a fire design model and the temperature distribution in the tunnel was estimated using numerical analysis. This led to a proposal for effective measures against subway tunnel fires.

• Tunnel and Underground Space
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• v.34 no.3
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• pp.196-207
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• 2024

In this study, a comprehensive management plan was proposed to ensure the stability of the existing subway when constructing ground structures adjacent to the subway. In the first step, the measurement inspection cycle is selected through proximity evaluation, in the second step, the stability of existing subway and station structures such as displacement and stress is reviewed through 3D numerical analysis considering the construction stage and groundwater influence, and in the third stage, the safety of train operation was reviewed by examining the track stability, and based on the numerical analysis results in the fourth stage, the displacement concentration section was selected as an intensive management section and it was proposed that intensive measurement management be performed.