• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.189-204
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• 2015

This paper presents the results of reduced scale model tests on the effect of fault zone characteristics on the tunnel deformation behavior. A series of model tests were carried out on deep tunnels considering different fault zone orientations and offset distance. The tunnelling process was simulated in the model tests using compressed air technique. During the tests, the tunnel and ground deformation were mainly monitored while reducing the pressure inside the tunnel and the relationship between the pressure level and the tunnel deformation were established. The results indicate that for a given offset distance the tunnel behavior is influenced the most when the fault zone dips vertically while smallest influence occurs when the fault zone dips 45 degrees.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.285-294
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• 2005

The behaviors of the ground in crossed zone and the existing upper tunnel in shallow cover due to the excavation of new lower tunnel crossed to that was studied. Model test was performed in the large scale test pit, the size was '$4.0m(width){\times}3.8m(height){\times}4.1m(length)$'. Test ground was constructed uniformly by sand in middle density and test with the crossed angle of $56^{\circ}$ (obliquely) were performed. The numerical analysis was performed on equal condition with model test. Results of the study by model test and numerical analysis show that earth pressure and settlement of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. Model test shows that upper tunnel blocks stress flow due to the longitudinal arching effect by excavation of lower tunnel.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.365-376
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• 2008

본 논문은 1차로 마제형 터널에서의 지반과 지보재의 상호 거동을 규명하기 위한 연구로서 터널의 주지보재인 숏크리트의 균열, 파괴하중 및 변형하는 거동양상을 실물크기의 터널모형실험을 통해 확인하였다. 이때 실험은 측압계수를 0.5, 1.0, 2.0으로 설정하여 각각 측압계수에 따른 결과를 확인하였다. 또한 실제 실험과 같은 조건을 설정한3차원 수치해석을 실시하여 각각의 결과를 비교 검증하였다. 터널모형 실험은 측압조건을 설정할 수 있도록 11개의 실린더를 사용하여 실험을 수행하였다. 3차원 수치해석 모델링은 터널모형실험과 가능하면 같은 조건으로 해석하기 위하여 모형실험으로부터 로드셀 및 LVDT를 통해 얻은 하중-변위곡선이 수치해석 시에도 재현되도록 하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.1
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• pp.87-94
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• 2010

This study mainly focused on the subsurface settlement due to shallow and deep tunneling in sandy ground. In order to figure out theoretical deformation patterns in association with the ground loss during the progress of tunneling, laboratory model tests using aluminum rods and finite element analyses using the CRISP program were carried out. As a result of comparison between the model test and the finite element analysis, the similar deformation patterns were found. In addition, it was identified that the most K values obtained from both the FEA and the model tests were distributed between Dyer et al. (1996) and Moh et al. (1996) of the field observation data. Based on the model test data, the linear equation of K for the sandy soil could be obtained.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.10a
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• pp.365-374
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• 2007

본 논문은 터널의 지반-지보재 상호 거동을 규명하기 위한 연구로서 주지보재인 숫크리트의 균열, 파괴하중 및 변형거동을 실물크기의 갱도모형실험을 통해 확인하고 3차원 수치 해석을 실시하여 각각의 결과를 비교 검증하였다. 갱도모형 실험은 실제 터널과 유사한 크기의 터널을 제작하여 11개 실린더에서 측압조건에 따라 하중을 가하여 실험을 수행하였다. 3차원 수치해석 모델링은 갱도모형실험과 가능하면 같은 조건으로 해석하기 위하여 모형실험으로부터 로드셀 및 LVDT를 통해 얻은 하중-변위곡선이 수치해석 시에도 재현되도록 하여 수행되었다.

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.313-325
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• 2006

In this study, scaled model tests were performed to investigate the deformation behaviors around tunnels located in anisotropic rocks. Fifteen types of test models which had respectively different joint angles and rock pressure conditions were made, where the modelling materials were the mixture of sand, plaster and water. All of the tested models showed the shear failure mechanism at the stress-concentrated regions and sliding phenomena according to the joint planes. The direction of joint inclination turned out to have great effect on the tunnel deformation behaviors. The models of joint inclination less than $30^{\circ}$ showed considerable floor heavings. The model of $50^{\circ}$ joint inclination showed the least tunnel convergence among the tested models regardless of rock pressure condition, so that it was thought as the most stable model. Furthermore, the failure mechanisms and deformation behaviors of tunnel models were strongly dependent on the coefficient of rock pressure.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.275-282
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• 2006

Since tunnels are linear type structures that have a long extent in comparison to their excavation or inner section, tunnels must be constructed in various ground conditions. In this study, laboratory model tests and theoretical analysis on a tunnel loads are carried out in the unconsolidated ground with inclined layers for tunnel excavation. Laboratory model tests are performed with the variation in the angle of the inclined layers and tunnel depth for the model ground with inclined layers. As for the ground materials, two dimensional model ground is prepared with aluminum rods and blocks with no cohesion, which are frictional resistance free between testing apparatus walls and ground materials, by establishing the ground materials self-supporting. Moreover tunnel load equation are newly induced so that comparisons between model test results and the theoretical results are conducted as well.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.2
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• pp.133-141
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• 2005

The behavior of the ground in crossed zone due to the excavation of new lower tunnel rectangularly crossed to that was studied by model tests and numerical analysis in shallow cover. Results of the model tests show that earth pressure of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. By the numerical analysis, minimum principal stress in crown of single tunnel has more decrease than parallel tunnel or crossed tunnel. Vertical stress at rectangularly crossed tunnel decrease more than single tunnel by stress shadow.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.37-47
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• 2008

Design and construction of tunnels require understanding the influence of groundwater. Particularly, it is essential to know how the drainage conditions at the tunnel boundary affect flow behavior of ground adjacent to the tunnels. In this study flow behavior of a leaking tunnel was investigated using physical model tests for tunnel depths and various hydraulic boundary conditions. Particular concerns were given to flow lines toward tunnels. Test results showed that the boundary conditions hardly influence on flow patterns and time required to reach steady state conditions. It is revealed that with an increase in water depth, flow lines concentrated to the drain holes. The physical tests were numerically simulated. Numerical results showed that the flow behavior was represented appropriately by considering filter-drain hole drainage rather than boundary drainage all over the lining.