• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.285-293
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• 2021

The construction of underground structures such as power supply lines, communication lines, utility tunnels has significantly increased worldwide for improving urban aesthetics ensuring citizen safety, and efficient use of underground space. Those underground structures are usually constructed along with vertical cylindrical shafts to facilitate their construction and maintenance. When constructing a vertical shaft through the open-cut method, the walls are mostly designed to be flexible, allowing a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the displacement of the surrounding ground. This study simulated stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model experiment. One quadrant of the axisymmetric vertical shaft and the ground were modeled, and ground excavation was simulated by shrinking the vertical shaft. The deformation occurring on the entire ground during the excavation was continuously evaluated through digital image analysis. The digital image analysis evaluated complex ground deformation which varied with wall displacement, distance from the wall, and ground depth. When the ground deformation data accumulate through the method used in this study, they can be used for developing shaft wall models in future for analyzing the earth pressure acting on them.

• 한국지반환경공학회 논문집
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• 제9권4호
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• pp.63-76
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• 2008

본 연구는 명확한 설계기준이 제시되어 있지 않은 국내의 수직구 설계기술 개선을 위하여 수행된 것으로, 국내외 설계기준 및 원형 수직구에 대한 이론적인 토압을 고찰하였고, 시공중인 수직구 2개소에 대하여 현장계측을 수행하여 수직구의 변형 및 작용하중분포 특성을 분석하였다. 심도별 토압 및 작용하중분포는 신영완(2007)이 제안한 이론토압과 유사한 경향을 나타내었으며, 수직구 주변 지반의 비균질, 비등방성에 의하여 편측 변형 및 토압이 발생되는 것으로 분석되었다. 토사 및 풍화암의 편하중비($R_p$)는 단면형상비(H/R)에 따라 상이한 결과를 나타내었고, 암반은 35.0%미만의 편하중비($R_p$)를 적용하는 것이 적정한 것으로 검토되었다.

• 대한토목학회논문집
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• 제30권6C호
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• pp.241-253
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• 2010

본 연구에서는 응답변위법을 수직구 내진설계에 적용하고 구조물의 응답을 정확하게 구할 수 있는 방법을 제시하고자 기반면, 지반의 상대변위 산정 방법, 하중 산정 및 적용 방법에 따른 3차원 유한요소해석을 수행하였다. 그 결과, 수직구 내진설계를 위한 기반면은 전단파속도가 1500m/s를 초과하는 지반을 선정하는 것이 가장 적합하며, 지반변위 산정 방법은 다층지반의 특성을 반영할 수 있는 double cosine이 가장 적합하다. 또한 응답변위법 해석을 위한 동토압 및 주면전단력 산정 시 구조물의 단면형상효과를 고려하는 것이 실제 수직구의 동적거동을 적절히 반영하며 경제적인 설계를 할 수 있음을 알 수 있었다.

• Geomechanics and Engineering
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• 제21권3호
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• pp.269-277
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• 2020

In this study, numerical analyses were conducted to investigate the load transfer mechanisms and dynamic responses between the vertical shaft and the surrounding soil using a dynamic analysis method and a pseudo-static method (called response displacement method, RDM). Numerical solutions were verified against data from the literature. A series of parametric studies was performed with three different transient motions and various surrounding soils. The results showed that the soil stratigraphy and excitation motions significantly influenced the dynamic behavior of the vertical shaft. Maximum values of the shear force and bending moment occurred near an interface between the soil layers. In addition, deformations and load distributions of the vertical shaft were highly influenced by the amplified seismic waves on the vertical shaft constructed in multi-layered soils. Throughout the comparison results between the dynamic analysis method and the RDM, the results from the dynamic analyses showed good agreement with those from the RDM calculated by a double-cosine method.

• 설비공학논문집
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• 제16권2호
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• pp.135-141
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• 2004

The present paper concerns a smoke movement in a tunnel fire with a vertical shaft. The model tunnel measured 13.4m long, 0.4m wide and 0.4m high. The cross section is 1： 20 of a full scale tunnel. Ethanol was used as a fuel. The fire size in model tests varied from 1.35 kW to 13.37 kW, which corresponds to full scale fires of 2.41 to 23.91 MW. Smoke front velocity and temperatrue were decreased due to the vertical shaft install. Temperature was reduced maximum about 2$0^{\circ}C$ at ceiling and about 23$^{\circ}C$ at vertical position. CO concentration was reduced as the vent width widened. When vent width was more than 15 cm, CO concentration was not reached 100 ppm. Descent degree of the smoke layer was confirmed through the visualization.

• 대한토목학회논문집
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• 제31권4C호
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• pp.109-116
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• 2011

본 연구에서는 수직구의 동적 거동특성 분석을 위하여 지반조건, 입력하중 특성, 하중 방향 등의 주요 인자를 고려하여 3차원 유한요소해석을 수행하였다. 그 결과로, 다층지반에 시공된 수직구는 하부 단단한 지층이 두꺼울수록 전단력과 휨모멘트가 최대 1.7배 크게 발생되며, 지층이 변화하는 경계면에서 가장 큰 단면력이 발생된다. 또한 입력하중의 주기 특성에 따라 수직구 동적거동은 서로 다르며, 수직구와 주변지반에서의 가속도 증폭 비율은 주변지반에서 최대 3배 이상 크게 나타났다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.883-888
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• 2008

Various effluents generated in cooking processes contribute a great deal to indoor air pollution among many other indoor pollutants such as dusts from outdoor and carbon dioxide from human body. Kitchen exhaust hoods are not believed to exhaust indoor contaminants properly in many cases, while generating too much noise. Instead of focusing on individual products of kitchen hoods, we should address the problem by attacking the ventilation system as a whole including vertical shafts and building air-tightness. In this study, it is intended to investigate the pressure distribution along the vertical shaft depending on various system parameters, such as shaft size, concurrent hood usage rate, roof fan, inlet pressure loss, and outdoor temperature. The maximum static pressure in the vertical shaft has been obtained using the method of design of experiments and analyzed by the analysis of variance. The results can be used for the design of kitchen exhaust systems by analyzing the pressure distributions in vertical shafts.

• 산업기술연구
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• 제30권A호
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• pp.17-23
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• 2010

Recently, a large number of open-pit mines are planning to change their mining method to underground types because the environmental concerns and legal regulations are increased with a rise in the standard of living. The K silica mine, which is one of them and located in Kyunggi province, is planning the establishment of a vertical shaft which will be used for ore-pass channel in their new glory hole mining method. This vertical shaft will be designed to join with a horizontal gangway excavated from the ground level. In this new mining system, the excavated ore particles will be stored inside a shaft and transported out with a help of a conveyor belt. Therefore the hang-up of ore particles in a shaft, the control of gate at the bottom of a shaft, the installation of dog-leg at the gate should be investigated identically. In this study, the PFC-2D code which is one of the discrete element numerical methods has been applied to simulate the particle flow mechanism in a shaft, and the optimum mine design has been proposed to maximize the productivity and to minimize the system damage.

• 한국유체기계학회 논문집
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• 제19권3호
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• pp.43-47
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• 2016

Pile foundations constructed on extremely cold regions cause serviceability problems of superstructures from repeated actions of ground freezing and thawing. Oil sand module plants are mainly constructed on seasonal frozen ground. Due to the freezing and thawing actions of grounds, vertical movements of piles have been observed. To solve these erratic pile movement problems, thin vertical layer of PET aggregates is installed around the pile shaft to prevent potential unfavorable pile movements. There is no known method to calculate "thin PET aggregate layer" -surrounded pile shaft resistance (capacity) against vertical loads; therefore, this experimental research is conducted. Specifically, in this study, horizontal (normal) pressures on pile shaft were assessed varying PET aggregate layer thickness based on the experiment.

• Geomechanics and Engineering
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• 제13권1호
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• pp.173-194
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• 2017

Access shaft is of critical importance to the construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, the design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative III: plain shaft, are proposed based on a simplified geological profile of the Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls.