• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.503-508
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• 2020

The three-dimensional precision numerical analysis was performed using the finite element model applied with the railway track model consisting of rails, As a result of analyzing the track deformation level of the existing tunnel due to the excavation work adjacent to the urban transit, it was found that the evaluation criteria (allowed values) of conventional railways lines were satisfied. Based on the numerical analysis, it was analyzed that the results of the prediction of the tunnel structural stability of due to the excavation work and the level of the tunnel deformation occurring at the actual site could be approximated as closely as possible.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.179-194
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• 2017

The segment lining design for shield tunnel is generally carried out by using the beam-spring model and the induced member forces from the model are strongly influenced by the components of the model such as imposed load, coefficient of subgrade reaction, location of segment joint and its stiffness. The structural models and stiffness of its connection part found used in abroad design cases is usually obtained as it is for the domestic design of segment of shield tunnel. Those models and stiffness in existing design cases are conventionally applied to a new tunnel design without any suitability review for the project. In this study, the application method of base components of the model such as the coefficient of subgrade reaction and modelling method to the segment lining design was suggested by carrying out the comparative study of the base elements for the member forces estimation of segment lining of shield tunnel.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.459-472
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• 2015

A recently developed tunnel section enlargement method can maintain traffic flow during construction by using a protector. By keeping traffic flowing, it can minimize the lost time and costs associated with diversions and also the accompanying environmental pollution. On the other hand, installing the protector can lengthen the construction period and increase the direct cost. This paper presents a method for analyzing the economic feasibility of tunnel section enlargement methods considering the direct construction cost and the indirect social cost. The indirect costs are divided into categories of: vehicle driving cost, travel time delay cost, and environmental pollution cost. The economic efficiency of existing technology is compared with the new method in an case study of Namsan Tunnel 3.

• Tunnel and Underground Space
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• v.21 no.1
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• pp.1-10
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• 2011

In these days, the development of optical fiber sensor technology is so remarkable that it can measure various physical and chemical quantities ranging from a few millimeters to over several kilometers. In addition, it is attempted to assess the structural integrity of the state of the advanced technologies and existing structures such as ships, aircrafts, and bridges. This paper introduced the case histories of the measuring technology of optical fiber applied on structures such as roads and tunnels. The case history using OTDR (Optical Time Domain Reflectometery) was also introduced in this paper. Measurement of the pre-convergence of a tunnel is essential to assess the safety of a tunnel and understand the geological conditions ahead of an advancing tunnel. Therefore, the pre-convergence measuring technology using OTDR is expected to substitute conventional measuring techniques.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.87-94
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• 2013

In recent years, tunnel construction is being increased in order to resolve traffic congestion around urban area, however there are a lot of difficulties due to restrictions such as interference with existing alignment, adjacent structures and cost increase of land acquisition as well as public complaints for negative environmental impacts near the expected tunnel construction site. Therefore, applications of close parallel tunnel have been increasing greatly. But close parallel tunnels cannot guarantee the stability compared with normal parallel tunnel which has enough distance between tunnels. So various methods to strengthen the pillar have been introduced recently, however there is few methods which consider the pillar behaviour in the state of compression. In this paper, the reinforcement methods which reflect the behavior of pillar were reviewed with comparision and analysis by numerical method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.2
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• pp.193-215
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• 2022

Recently, ground structures have reached saturation, and underground construction using underground structures such as tunnels has been in the spotlight as a way to solve increasing traffic difficulties and environmental problems. However, due to the increasing number of underground structures, close construction is inevitable for continuous underground development. When a new underground structure is constructed closely, stability may become weak due to the influence on the existing tunnel, which may cause collapse. Therefore, analyzing the stability of existing tunnels due to new structures is an essential consideration. In this study, the effect of excavating new tunnels under parallel tunnels on existing parallel tunnels was analyzed using numerical analysis. Using the Displacement Control Model (DCM), the volume loss generated during construction was simulated into three case (0.5%, 1.0%, and 1.5%). Based on the center of the pillar, the distance where the new tunnel is located was set to 5 m, 6 m, 7 m, 8 m, 9 m, and the space for each distance were set to 5 (0D₁, 0.37D₁, 0.75D₁, 1.13D₁, 1.5D₁). In general, as the volume loss increased and the distance approached, the maximum displacement and angular displacement increased, and the strength/stress ratio to evaluate the stability of the pillar also decreased. As a result, when the distance between the new tunnel and the center of the pillar is 5 m, the space is 0D₁, and the volume loss is 1.5%, the stability of the existing parallel tunnel is the weakest.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.725-732
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• 2011

The vibration resulting from railway operation is transmitted through the tunnel to adjacent buildings and the transmitted vibration radiates structure-borne noise which is causing a lot of public complaints by its negative effects to the buildings near tunnel. This study performed the parametric study about sleeper space and track support stiffness in order to reduce vibration on the concrete track and near structures. In this study, it was compared and performed vibration analysis and field test about these. In addition, as changing the sleeper space and track support stiffness, vibration of the structures was evaluated. Via this study, in terms of reducing the figure of the sleeper space and track support stiffness to the half, as vibrating acceleration transmitted through concrete round is getting reduced, it transmitted through the tunnel was analysed to the same phenomena. In conclusion, suggested track structure into this study, it can be applied to the track structure of existing line, and it is expected to be a new effective anti-vibration method to prevent public complaints.

• Tunnel and Underground Space
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• v.3 no.1
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• pp.63-79
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• 1993

The design of tunnels in rock masses often demands more informations on geologic features and rock mass properties than acquired by usual field survey and laboratory testings. In practice, the situation that a perfect set of geological and mechanical input data is given to geomechanics design engineer is rare, while the engineers are asked to achieve a high level of reliability in their design products. This study presents an artificial neural network which is developed to resolve the difficulties encountered in conventional design techniques, particulary the problem of deteriorating the confidence of existing numerical techniques such as the finite element, boundary element and distinct element methods due to the incomplete adn vague input data. The neural network has inferring capabilities to identify the possible failure modes, support requirements and its timing for underground openings, from previous case histories. Use of the neural network has resulted in a better estimate of the correlation between systems of rock mass classifications such as the RMR and Q systems. A back propagation learning algorithm together with a multi-layer network structure is adopted to enhance the inferential accuracy and efficiency of the neural network. A series of experiments comparing the results of the neural network with the actual field observations are performed to demonstrate the abilities of the artificial neural network as a new tunnel design assistance system.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.535-542
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• 2010

Various difficulties have been increased in the construction of public structure; like the road in the overcrowding urban area, because of civil complaint, cost and period of construction. In oder to overcome these social problems, the tunnel has been planned the road design. Despite the resolution, there are many technical problems when constructed near facilities. The design of new tunnel below the existing service reservoir is applied to the ambient vibration blasting using Plasma. The result of test blasting was exceeded the standard ("2kine"). So it was considered a countermeasure for the vibration reduction applied to change the controlled blasting method, reduce the charge, add the pre middle horizontal hole in the cut blasting site, and so on. The result was satisfied the standard. Accordingly, if the quality of blasting process can be managed well, the application of this alternative method is highly effective one. Also, based on cost analysis between two methods, the alternative method is very competitive.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.181-187
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• 2003

This paper describes a study of the influence of shield tunnel construction on the displacements and stresses induced in the linings of existing nearby parallel tunnels. The paper presents a brief review of a set of laboratory scale model research programme investigating the influence of tunnel proximity and alignment, liner stiffness on the nature of the interactions between closely spaced tunnels in clay. A total of two sets of carefully controlled physical model tests were performed. A cylindrical test tank was developed and used to produce clay samples of Speswhite kaolin. In each of the tests, three model tunnels were installed in order to conduct two interaction exts that have been carried out to investigate the interaction problem between parallel tunnels. The results of these tests are compared with the results of finite element analysis to investigate the techniques that must be used to obtain reliable numerical solutions to this type of problem.