• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.85-92
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• 2021

The purpose of this paper is to understand the key factors for efficient maintenance of rapidly aging facilities. Therefore, the safety inspection/diagnosis reports accumulated in the unstructured data were collected and preprocessed. Then, the analysis was performed using a text mining analysis method. The derived vulnerabilities of tunnel facilities can be used as elements of inspections that take into account the characteristics of individual facilities during regular inspections and daily inspections in the short term. In addition, if detailed specification information and other inspection results(safety, durability, and ease of use) are used for analysis, it provides a stepping stone for supporting preemptive maintenance decision-making in the long term.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.2
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• pp.151-160
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• 2004

This study has carried out a series of field investigation for a ASSM railway tunnel which was constructed several decades ago. It appears that the tunnel lining was cracked in the region of arching structure. Precise inspection is carried out for this region with various non-destructive testing equipments. Based on the inspection results, the cause and the effect of tunnel defects were discussed by conducting the evaluation of tunnel safety with numerical analysis.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1080-1084
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• 2007

Recently, as demands of new railway and the relocation of existing line, a number of tunnel structures have been constructed. Tunnel structures contribute to minimize the cost and time of transport, but in case of railway fire accident bring serious damages of human life caused by narrowness of shelter, smoke and high temperature, difficulty in rescue. For that reason, at the beginning of plan of tunnel, the optimum design of safety facility in tunnel for minimizing the risks and satisfying the safety standard is needed. In this study, QRA(Quantitative Risk Analysis) technique is applied to design of railway tunnel for assuring the safety function and estimating the risk of safety. The case study is carried out to verify the QRA technique for railway tunnels in Iksan-Sili.

• Wind and Structures
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• v.19 no.2
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• pp.185-197
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• 2014

Ventilation and fire safety design in road tunnels are one of the most complex issues that need to be carefully considered and analysed in the designing stage of any potential upgrade of ventilation and other fire safety systems in tunnels. Placement road tunnels space has an important influence on fire safety, especially when considering the effect of adverse wind conditions that significantly influence ventilation characteristics. The appropriate analysis of fire and smoke control is almost impossible without the use of modern simulation tools (e.g., CFD) due to a large number of influential parameters and consequently extensive data. The impact of the strong wind is briefly presented in this paper in the case of a longitudinally ventilated road tunnel Kastelec, which is exposed to various severe wind conditions that significantly influence its fire safety. The possibility of using CFD simulations in the analysis of the tunnel placement in space terms negative effect of wind influence on the tunnel ventilation is clearly indicated.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.491-502
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• 2008

A certain range of the original ground around the tunnel should be preserved to ensure structural safety of the tunnel when other structures are made around the tunnel, and thus this range is defined as safety zone of the tunnel. The main points to ensure the stability of an existing tunnel when constructing a new tunnel in an inter-crossing area are distance between two tunnels, size of the new tunnel, excavation method for the new tunnel, ground condition around the tunnel, and lining type of the existing tunnel etc. When the new tunnel is excavated above the existing tunnel, the existing tunnel is likely to suffer deformation at a crown zone, damage of arching effect, and live load of the new tunnel etc. On the other hand, when the new tunnel is excavated below the existing tunnel, the existing tunnel is likely to be damaged due to settlement. This study has been made on the behavior of the existing tunnel by means of model test and numerical analysis when the new tunnel is excavated below the existing tunnel. Safety zone of the tunnel was estimated by the results of strength/stress ratio obtained from numerical analysis, and the movement of ground was estimated by the model test. The results of earth pressure, ground displacements, and convergence of the tunnel obtained from model test were compared with those of numerical analysis, and show a similar trend.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.47-57
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• 2000

It is difficult to calculate factor of safety of a tunnel by applying any analytical method based upon limit equilibrium method since the shape of failure plane in tunnel analysis can not be easily assumed in advance. To cope with this shortcoming, a method is suggested to calculate safety factor of a tunnel by numerical analysis using strength reduction technique. A circular tunnel excavated in a homogeneous rock was selected as an example problem and factors of safety were calculated for no-supported, partly-supported, and completely-supported cases respectively. Meshes with 3 different sizes were examined for a sensitivity analysis. For the verification of the proposed method, a limit equilibrium analysis was conducted and compared with the numerical analysis. The proposed method herein can be used to calculate factor of safety of a tunnel regardless of tunnel shape or geological conditions, and thus can contribute for the improved design and stability assessment of tunnels.

• Journal of Korean Society of societal Security
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• v.3 no.2
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• pp.57-64
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• 2010

In this study, the behavior and safety of an existing tunnel and its facilities are investigated when a new tunnel adjacent to the existing tunnel is blasted. The design of the new tunnel puts priority on stability of the tunnel itself over the safety of the facilities which are installed within the existing tunnel such as jet fans. And thus, a detailed consideration on securing the safety of the existing facilities has been insufficient. An analysis on the types of traffic accidents in the last ten years shows that most incidents were due to the driver's improper response in emergency situations and unexpected obstacles. In consideration of this analysis, the safety of the facilities in the existing tunnel was secured by minimizing the charging amount for each hangfire and changing the excavation method of evacuation communication shelters to the large center hole cut blasting method to reduce blasting vibration. For a more quantitative analysis, measurement devices were installed inside the existing tunnel, at houses adjacent to the new tunnel, near jet fans in the existing tunnel. This enabled real time measurement of displacements of the existing tunnel, adjacent houses, and jet fans without interrupting traffic flow. Therefore, the improvements of charging amount for each hangfire, the blasting method, and the measurement method are suggested in this paper to secure the safety of the facilities in the existing tunnel when a new tunnel, located on a large city and adjacent to an existing tunnel, is designed.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.29-36
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• 2015

Common utility tunnel is essential to the daily lives of people underground utilities (electricity, gas and supply facilities such as water, communication facilities, sewer facilities, etc.) to improve the appearance by co-acceptance and disaster prevention, important for the conservation of the city's population was concentrated road construction the city-based facilities. There is recognition of the importance of the various supply treatment facilities in common utility tunnel as infrastructure to accommodate joint according to the city expanded, the demand for infrastructure. In this paper, a cost-benefit analysis using a one-time occurrence, without simply relying on cost or current cost, project manager for the city-dimensional feasibility study conducted, the user level of the maintenance costs and user costs, including social costs items from various angles can be investigated and proposed a mechanism of economic feasibility common utility tunnel. Evaluation of the proposed technique is cost-benefit and cost caused by installing common utility tunnel the existing pipeline area - was investigated by the benefit analysis, extended and repeated common utility tunnel installation depends much affected by the excavation, so users of reducing the number of repeat excavation convenience can be seen that this occurs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.2
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• pp.185-191
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• 2000

The safety problem of aged tunnels has been emphasized. For the effective maintenance, site inspection of tunnel structures and surrounding grounds are required periodically. Also, the determination of safety of tunnels is not a simple problem. So the role experienced engineer in the maintenance is very important and development of an expert system that can perform as the engineers, has been needed. In this study, from the results of numerical analysis in several case, new precision inspection rules which can substitute actual numerical analysis are determined by a commercial program FLAC and regression analysis under various parameters such as material property, lining thickness, overburden and laterial coefficients. They are added to the knowledge base to determine safety of tunnel lining. To verify the expert system, the results are compared with an existing tunnel diagnosis report. It can be concluded that the new rule are well represented the actual numerical analysis under various site conditions. Therefore it is expected that the systematic management for effective maintenance of tunnel structure will be possible.

• Geomechanics and Engineering
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• v.37 no.6
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• pp.599-614
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• 2024

To evaluate the safety status of deteriorated segments in a submarine shield tunnel during its service life, a seepage model was established based on a cross-sea shield tunnel project. This model was used to study the migration patterns of erosive ions within the shield segments. Based on these laws, the degree of deterioration of the segments was determined. Using the derived analytical solution, the internal forces within the segments were calculated. Lastly, by applying the formula for calculating safety factors, the variation trends in the safety factors of segments with different degrees of deterioration were obtained. The findings demonstrate that corrosive seawater presents the evolution characteristics of continuous seepage from the outside to the inside of the tunnel. The nearby seepage field shows locally concentrated characteristics when there is leakage at the joint, which causes the seepage field's depth and scope to significantly increase. The chlorine ion content decreases gradually with the increase of the distance from the outer surface of the tunnel. The penetration of erosion ions in the segment is facilitated by the presence of water pressure. The ion content of the entire ring segment lining structure is related in the following order: vault < haunch < springing. The difference in the segment's rate of increase in chlorine ion content decreases as service time increases. Based on the analytical solution calculation, the segment's safety factor drops more when the joint leaks than when its intact, and the change rate between the two states exhibits a general downward trend. The safety factor shows a similar change rule at different water depths and continuously decreases at the same segment position as the water depth increases. The three phases of "sudden drop-rise-stability" are represented by a "spoon-shaped" change rule on the safety factor's change curve. The issue of the poor applicability of indicators in earlier studies is resolved by the analytical solution, which only requires determining the loss degree of the segment lining's effective bearing thickness to calculate the safety factor of any cross-section of the shield tunnel. The analytical solution's computation results, however, have some safety margins and are cautious. The process of establishing the evaluation model indicates that the secondary lining made of molded concrete can also have its safety status assessed using the analytical solution. It is very important for the safe operation of the tunnel and the safety of people's property and has a wide range of applications.