• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.1
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• pp.27-36
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• 2005

The objective of this study was to analyze the smoke movement and to investigate the effect of exhaust ventilation using by shafts for case of fire in long tunnels. Based on Froude modeling, the 1/50 scaled model tunnel (20 m long) was constructed by acrylic tubes and test were carried out systematically. The results of the shaft height test show that the effect on exhaust ventilation by a shaft delays the propagation time of backlayering, and the temperature decreases as the shaft height increases. If the fire occurs downstream of the shaft, the backlayering develops to get stronger by the shaft exhaust effect and then the propagation of CO and temperature increase along with propagation of CO. That is to say, in the case of fire downstream of the shaft, the shaft has the advantage of smoke exhaust effects, but it might result in a dangerous situation for the escaping passengers due to the more developed backlayering.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.6
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• pp.431-450
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• 2011

When a circular vertical shaft is constructed below the groundwater level, additional forces caused by groundwater flow besides horizontal effective stresses will act on the wall. The inward direction of the groundwater flow will be inclined to the vertical wall and its direction will change depending on the wall depth. In this paper, to figure out the effect of seepage forces acting on the circular vertical shaft, the slope of the inclined flow varying with the depth is divided into vertical and horizontal components to derive the coefficient of earth pressure considering the seepage pressure and to obtain the vertical stress by taking the seepage pressure into account. The control volume in this study is assumed to be the same with that of the dry ground condition within which the earth pressure is acting on the wall by the creation of the plastic zone during shaft excavation. An example study shows that the vertical stress increases by about 1.4 times and the horizontal earth pressure increases up to 2.5 times compared to the dry ground condition. The estimated values from the proposed equation considering seepage forces and the calculated values from numerical analysis with "effective stress plus seepage force" show similar values, which verifies appropriateness of the proposed equation to estimate the earth pressure under the seepage condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.619-625
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• 2019

It is difficult to design because of the plug-holing phenomenon in which the amount of smoke discharged from the vertical vent is smaller than the designed amount of smoke. In this study, the effect of cross-sectional area ratio of tunnel and natural ventilation and heat release rate of fire source on plug-holing phenomenon occurring in natural ventilation system was experimentally analyzed. In the experiment model reduced to 1/20 size, the aspect ratio of the tunnel and the vertical vent was fixed, and the influence on the plug-holing phenomenon was confirmed by varying the sectional area ratio of the tunnel and the vertical vent. Experimental results show that the plug-holing phenomenon is caused by the comparison of the smoke boundary layer temperature with the temperature in the vertical vents, and the flow and temperature distribution characteristics under the vertical vents are changed as the cross-sectional area ratio of the tunnel and vertical vents increases. The plug-holing phenomenon is affected by the cross-sectional area ratio between the tunnel and the vertical ventilation. The greater the cross-sectional area ratio, the greater the probability of plug-holing.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.108-108
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• 2023

기후변화 및 도시화로 인해 도시 내에서 증가하는 홍수로 인명 및 재산피해가 꾸준히 발생하고 있다. 특히 2022년 8월 8일 서울특별시 및 경기도 지역에 내린 폭우로 인해 8명 이상의 인명피해와 1300억원 이상의 재산피해가 발생하였다. 이러한 도시홍수를 근본적으로 방어하기 위하여 미국, 일본 등의 국가에서는 대심도 빗물저류배수터널을 활용하고 있다. 국내에서도 2011년 서울특별시 강서구 및 양천구에 발생하는 홍수를 방어하기 위하여 국내 최초 대심도 빗물저류배수터널인 '신월 빗물저류배수시설'을 건설하여 현재 운영 중에 있다. 대심도 빗물저류배수터널은 초기 개수로 흐름에서 만관 후 관수로 흐름으로 전이되는 구조물로 계획과 운영이 매우 어려운 시설이다. 이에 미국, 일본, 중국, 이탈리아 등 국가에서 대심도 빗물저류배수터널과 관련한 연구가 활발히 진행되고 있다. 본 연구에서는 대심도 빗물저류배수터널의 유입시설 중 감세부에 해당하는 수직갱과 감세지의 깊이에 따른 감세지 바닥 압력변화를 알아보기 위하여 수리실험을 수행하였다. 그 결과 감세지 깊이가 깊어질수록 바닥면의 압력이 증가하는 것으로 분석되었으며 바닥면의 압력이 감세지 깊이만큼의 정수압을 포함하는 경우 정수압 대비 최대 2.0배, 정수압을 포함하지 않는 경우 정수압 대비 최대 1.0배 인 것으로 분석되었다. 수직갱 깊이에 대한 실험 결과는 수직갱 깊이가 짧아질수록 압력이 감소하는 경향을 보이는 것으로 분석되었는데 이는 회전수 및 회전력과 관련 있는 것으로 판단된다. 향후 수직갱 직경, 수직갱 깊이에 대한 추가 연구가 필요한 것판단되며 이를 통하여 수직갱 깊이-감세지 깊이에 대한 정량적인 연구와 분석을 통해 경제적이고 안정적인 대심도 빗물저류배수터널 감세지 설계가이드라인을 제시하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.109-122
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• 2003

In order to release the pressure fluctuations and micro-pressure wave induced by the entering of train into the small cross sectional tunnel, it has been reported that the construction of air shaft has more advantages with respect to economy and constructability than the enlargement of cross section of existing tunnel. The field monitorings and analytical studies were conducted simultaneously in this study to analyze the mechanical behavior of existing railway tunnel, new cross tunnel and new shaft by the construction of new shaft nearby. The results showed that the minimum distance from existing tunnel to new shaft which secures the stability of existing tunnel was found to be half diameter of existing tunnel. On the three dimensional mechanical behavior of existing tunnel by the construction of new shaft, the results from the analytical study and field monitoring had a similar trend. The analytical study and field monitoring results, however, produced somewhat different results on the mechanical behavior of new shaft itself. These conclusions induce that the analytical method which has been applied on the analyses of horizontal tunnel could not be applied in the same way on the analysis of vertical shaft.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.74-74
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• 2015

최근 홍수의 특성과 피해 양상은 과거와는 다르게 변화하고 있으며, 급격한 도시화로 인하여 기존 하천유역의 저류 능력이 감소하였으며 이러한 한계를 극복하기 위하여 이미 외국에서는 대심도 터널을 활용한 홍수재해 관리방안이 오래전부터 활용되어 왔다. 본 연구에서는 대심도 터널의 유입구, 수직갱, 감세지, 배수터널과 같은 시설물 중 대심도 터널 설계 시 수직 유입구를 통해 유입되는 유량의 에너지를 완화하고 효과적으로 배수 할 수 있도록 중요한 역할을 하는 감세지의 효율적인 깊이 산정을 위하여 수리모형실험을 실시하였으며, 모형은 Froude 상사법칙을 사용하여 원형의 1/18크기로 제작하였다. 본 연구에서 실시한 감세지 모형의 깊이는 0.278 m(원형 5.0 m), 0.417 m(원형 7.5 m)이며, 각 감세지 깊이별 수직 유입구 3개소(저지수직구1, 저지수직구2, 고지수직구) 및 5가지의 유량 CASE에 대하여 감세지 바닥면 압력을 비교?분석 하였다. 수직 유입구 3개소의 설계조건에 따른 감세지 깊이별 바닥면 압력 분포 평가를 실시한 결과 저지수직구1의 감세지 깊이 0.278 m(원형 5.0m)에서는 최대 압력이 4번 지점에서 $0.075kg/cm^2$(원형 1.30 MPa)이 측정 되었으며, 0.417 m(원형 7.5m)에서는 최대 압력이 1번지점에서 $0.089kg/cm^2$(원형 1.54MPa)이 측정되었다. 또한 저지수직구2의 감세지 깊이 0.278 m(원형 5.0 m)에서는 최대 압력이 1번 지점에서 $0.074kg/cm^2$(원형 1.28 MPa)이 측정 되었으며, 0.417 m(원형 7.5 m)에서는 최대 압력이 2번지점에서 $0.088kg/cm^2$(원형 1.52 MPa)이 측정되었다. 고지수직구의 감세지 깊이 0.278 m(원형 5.0 m)에서는 최대 압력이 3번 지점에서 $0.082kg/cm^2$(원형 1.42 MPa)이 측정 되었으며, 0.417 m(원형 7.5 m)에서는 최대 압력이 1번지점에서 $0.092kg/cm^2$(원형 1.59 MPa)이 측정되었다. 본 연구에서 실시한 수리모형실험의 결과 저유량에서 고유량으로 갈수록 최대압력지점은 반시계방향으로 움직이는 것을 알 수 있으며, 이는 수직 유입구의 설계조건에 따른 수직갱에서의 회전수차에 의하여 발생하는 것으로 분석하였다. 따라서 적절한 감세지 깊이 산정을 위해서 대심도터널의 수직 유입구(유입구형태, 수직갱)의 평가가 함께 유기적으로 이루어져야 할 것으로 판단된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.887-897
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• 2018

3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.

• Journal of the Korean Magnetics Society
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• v.16 no.6
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• pp.271-275
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• 2006

We investigated the magnetoresistance of perpendicularly magnetized magnetic tunnel junction composed of Co/Pd multilayers. The magnetoresistance was maximized with Co electrodes of about 5 nm thickness, which evidenced the important role of the interface in tunneling process. Both the change in perpendicular magnetic anisotropy and improvement of junction resistance were observed with changing Co sublayers, while the spin scattering became dominant with increasing Pd sublayers.

• Geotechnical Engineering
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• v.29 no.11
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• pp.27-34
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• 2013

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.559-570
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• 2013

High speed railway can transport large quantity of people and commodities in a short time and has become one of the most desirable and environmentally friendly transportation. However, it is hard to have a complicated route for high speed railways, construction of tunnels is essential to pass through a mountain area. When a high speed train enters a tunnel, pressure wave is created in a tunnel and the wave causes micro pressure wave and discomfort to passengers. In order to alleviate pressure wave in a tunnel, constructing a vertical shaft is one of the most efficient ways. This study represents a numerical analysis module, which takes into account the effect of a vertical shaft in a tunnel. The module can be used in a numerical program (TTMA) specialized for aerodynamics in a tunnel, and it was validated by comparing numerical results with various measurements in Emmequerung tunnel and results from numerical analysis using Fluent.