• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5C
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• pp.359-368
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• 2006

After construction, time-variant seepage and long-term underground motion are representative factors to understand the abnormal behavior of tunnels. In this study, numerical models have been developed to analyze the behavior of tunnels associated with seepage and long-term underground motion. Possible scenarios have been investigated to establish causes-and-results mechanisms. Various parameters such as permeability of tunnel filter, seepage condition, water table, long-term rock mass load, size of damaged zone due to excessive blasting have been investigated. These are divided into two sub-parts depending on the tunnel type and major loading mechanisms depending on the types. For the soft ground tunnels, the behavior associated with seepage conditions has been studied and the effect of permeability change in tunnel-filter and the effect of water-table change which are seldom measurable are investigated in detail. For the rock mass tunnels, tunnel behavior associated with the visco-plastic behavior of rock mass has been studied and the long-term rock mass loads as a result of relaxation and creep have been considered.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.282-291
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• 2005

사암 및 이암을 기반암으로 하는 산악지역에 건설되는 2-아치 (2-arch) 터널의 거동을 터널설계 단계에서 분석하기 위하여 대규모 실내 모형실험을 실시하였다. 터널이 시공될 예정인 지반과 유사한 지질공학적 특성을 가지는 콘크리트 블록을 이용하여 모형지반을 조성하였다. 모형실험은 중앙터널 (pilot tunnel) 굴착을 포함한 여러 단계의 굴착과정으로 구분하여 실시되었다. 또한 터널 .공용기간 중 터널의 거동을 연구하기 위하여 터널굴착 완료 후 상재하중을 작용시켰다. 실험결과에 의하면 대부분의 지반변위는 중앙터널 굴착에 의해 발생했으며, 그 이후 터널 굴착단계에서의 변위발생은 미미한 것으로 나타났다. 또한 대부분의 지중변위는 0.25D 이내의 범위에서 발생하였다. 여기서 D 는 터널의 폭이다. 한편 실험결과를 분석하여 경암에 시공되는 2-아치 터널의 중앙벽체(centre pillar)에 작용하는 하중에 대한 경험적인 공식을 제시하였다. 터널시공 완료 후 공용기간 중 상재하중이 작용할 경우 그 크기에 따라서는 터널굴착에 의해 발생한 것보다 더 큰 지중변위가 발생할 수 있는 것으로 분석되었다. 터널의 거동은 중앙벽체의 강성에 큰 영향을 받는 것으로 나타나 이를 터널설계에 반영하여 중앙벽체의 강성을 증가시켰다. 현재 터널시공을 위한 사전작업이 진행 중에 있으며, 터널의 굴착은 2005년 하반기에 실시될 예정이다.

• Tunnel and Underground Space
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• v.20 no.3
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• pp.131-144
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• 2010

The design and construction of tunnels has been followed an large parallel tunnels with a small clearance because of the various conditions. Rock pillar between each single tunnel is supposed to be under heavy load by rock mass. The stability of pillar is very important for the ensure the stability of the large parallel tunnels. In this study, the analysis of stress state of pillar at various construction cases is reviewed to investigate the mechanical behaviour of tunnels and stability of the pillar.

• Geotechnical Engineering
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• v.1 no.1
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• pp.31-46
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• 1985

An extensive program of tunnel instrumentation has been Implemented in the construction of the Seoul Subway Line 3 and 4, in which the NATM was adopted as the main tunnelling technique. Among more than ten instrumented sections in the downtown area, five representative test sections were selected for analysis in this study, with an emphasis on the surface settlement and crown settlement. Variations of the surface and crown settlement. Variations of the governing factors, such as ground conditions, tunnel geometry, and construction conditions are described in this paper. Possible mechanisms for ground deformations occurring at different stages of tunnel construction are formulated, based on overall interpretation of the field observations and data obtained.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.301-312
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• 2003

This paper considers the stresses and pore pressures induced in soft ground due to tunnelling and it presents and discusses the approach methods for estimating the stability of the tunnel and its heading during drained and undrained condition. In practical, the undrained analyses of the face stability of shield tunnelling in soft soil, are carried out based on the field data measured during tunnelling and the results are also evaluated.

• Tunnel and Underground Space
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• v.15 no.6 s.59
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• pp.400-410
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• 2005

During excavation of shallow tunnels in soft ground, failure mechanism around the tunnel face have major influence on the stability of tunnels. In this paper, a series of laboratory tests under plane strain condition on the small scale of a shallow tunnel considering unsupported tunnel length has been performed. The results have shown that tunnel failure mechanism changes from failure mode 1 to failure mode 2 as unsupported tunnel length increases. By comparing the experimental and the numerical results, the loosening pressure for the shallow tunnel and progressive failure have been investigated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.4
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• pp.341-354
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• 2016

This article is to apply the tunnel support system selected after comparatively analyzing of RMR and tunnel instrumentation between the tunnel behavior characteristic predicted through geotechnical investigations and the numerical analysis at the design stage and the properties deformation occurred at the construction stage. This attempt results from the behavior characteristic of the tunnel excavation ground shown differently in accordance with the ground quality and reinforcement method. This, therefore, provide the data and results analysed the actual decision RMR-crown settlement & convergence and reduction of material property of ground as parameters. Also, it's shown that the tunnel designer is able to predict tunnel behavior characteristic when designing in bedrock areas excessively distributed faults and fractured zones.

• 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.

• Magazine of korean Tunnelling and Underground Space Association
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• v.2 no.1
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• pp.130-138
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• 2000

본 연구에서는 수평보강재로 보강된 터널 막장의 거동에 관한 매개변수 연구결과를 다루었다. 매개변수 연구에서는 막장주변의 3차원 응력-변형율 거동을 보다 효율적으로 모델링하기 위해 3차원 유한요소해석 모형을 적용하였으며 보강패턴에 따른 막장의 거동을 고찰하기 위해 다양한 경계조건에 대한 해석을 수행하였다. 해석결과를 토대로 막장의 응력해방-변위거동의 관계를 고찰하였으며, 보강패턴과 막장 변위의 정성${\cdot}$정량적인 관계를 제시함과 아울러서 향후 수행될 반경험적 설계/해석법의 개발을 위한 데이터베이스를 구축하였다. 한편, 해석결과 보강재 타설수 및 길이 등 각 보강설계 인자에 대한 임계치가 존재하는 것으로 나타났으며 따라서 보다 안전하고 경제적인 설계를 위해서는 이를 고려하여야 할 것으로 판단된다.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.265-280
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• 2023

Water leakage in tunnels is a defect that can affect tunnel stability and the ground movement by changing the stress and pore water pressure of the surrounding ground. Long-term or large-scale water leaks may lead to damage of tunnel structure and the surrounding environment, such as tunnel lining instability and ground surface settlement. The present study numerically investigated the effects of water leakage on the structural stability of a tunnel and the ground behavior. The tunnel was assumed to be under undrained conditions for preventing the inflow of the surrounding water and leaks occurred in the concrete lining after completion of the tunnel construction. A coupled hydro-mechanical analysis using a TOUGH-FLAC simulator developed in Python was conducted for assessing the leakage induced-behavior of the tunnel structure and ground under different conditions of the amount and location of water leak. Additionally, the effect of hydro-mechanical coupling terms on the results of coupled response was investigated and discussed.