• 한국지반공학회지:지반
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• 제12권1호
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• pp.87-110
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• 1996

터널굴착시, 막장부근의 3차원 효과를 반영하기 위해 주로 경험적인 하중분담률 개념을 도입한 2차원 유한차분법 수치해석이 수행된다. 본 논문에서는 3차원 수치해석을 수행하고 그 해석 결과와 2차원 수치해석 결과를 비교함으로써 합리적인 하중분담률의 적용 가능성 및 막장 부근의 음력집중 문제를 규명하고자 하였다. 무지보 굴착길이, 초기지중응력, 지반종류, 단면크기와 터널심도등의 하중분담률에 주된 영향을 미치는 인자들에 대한 매개변수 연구를 수행하고, 그 결과를 토대로 서울지하철의 대표적인 단면에 대해 적용가능한 하중분담률을 추천하였다.

• Geomechanics and Engineering
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• 제28권2호
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• pp.145-155
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• 2022

Safety is a most important parameters in underground railway transportation; Also stability of underground tunnel is very important in tunneling engineering. Design of a reliable support system requires an evaluation of both ground demand and support capacity. Iran's traditional railway tunnels are mainly supported with masonry structures or unsupported in high quality rock masses. A decrease in rock mass quality due to changes in groundwater regime creep and fatigue in rock and similar phenomena causes tunnel safety to decrease during time. The case study is an old tunnel in Iran, called "Keshvar"; it is more than 50 years old railway organization. In operating this Tunnel, until the several problems came up based on stability and leaking water. The goal of study is evaluation of the various reinforcement systems for supporting of the tunnel. The optimal selection of the reinforcement system is examined using TOPSIS Fuzzy method in light of the looming and available uncertainties. Several factors such as; the tunnel span, maintenance, drainage, sealing, ventilation, cost and safety were based to choose the method and system of designing. Therefore, by identifying these parameters, an optimal reinforcement system was selected and introduced. Based on optimization system for analysis, it is revealed that the systematic rock bolts and shotcrete protection had a most appropriate result for these kind of tunnel in Iran.

• 터널과지하공간
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• 제13권6호
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• pp.421-433
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• 2003

자원개발에 있어서 환경문제로 석회석광산의 채굴이 노천에서 지하채굴로 점차 전환되면서 석회석 채광에 따르는 갱도의 안전문제가 대두되고 있다. 무지보로 유지해야 하는 갱도의 크기문제를 결정하는 것이 현장에서 가장 어려 문제중의 하나이다. 따라서 석회석 지하채광장과 갱도에서 Q시스템과 RMR 암반분류법을 적용하여 지하갱도의 안전성을 평가하기 위한 암반분류법을 개발하기 위해서 두 개의 석회석 광산을 대상으로 암반조사가 이루어 졌다. 기본적으로 Q 시스템과 RMR 암반분류법의 상관관계를 이용하여, 석회석 광산에 적용할 수 있도록 암반분류법을 수정하였고 또한 무지보 안전갱도 폭을 결정하기 위한 새로운 시도가 이루어 졌다.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.74-81
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• 2004

The KSNP Steam Generators (Youngkwang Unit 3 and 4, Ulchin Unit 3 and 4) have a problem of U-tube fretting wear due to Flow Induced Vibration (FIV). In particular, the wear is localized and concentrated in a small area of upper part of U-bend in the Central Cavity region. The region has some conditions susceptible to the FIV, which are high flow velocity, high void fraction, and long unsupported span. Even though the FIV could be occurred by many mechanisms, the main mechanism would be fluid-elastic instability, or turbulent excitation. To remedy the problem, Eggcrate Flow Distribution Plate (EFDP) was installed in the Central Cavity region or Ulchin Unit 5 and 6 steam generators, so that it reduces the flow velocity in the region to a certain level. However, the cause of the FIV and the effectiveness of the EFDP was not thoroughly studied and checked. In this study, therefore the Stability Ratio (SR), which is the ratio of the actual velocity to the critical velocity, was compared between the value before the installation of EFDP and that after. Also the possibility of fluid-elastic instability of KSNP steam generator and the effectiveness of EFDP were checked based on the ATHOS3 code calculation and the Pettigrew's experimental results. The calculated results were plotted in a fluid-elastic instability criteria-diagram (Pettigrew, 1998, Fig. 9). The plotted result showed that KSNP steam generator with EFDP had the margin of Fluid-Elastic Instability by almost 25％.