• Title, Summary, Keyword: 기압장벽고

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A Study on the Natural Ventilation Force in Tunnels (터널형 지하공간내의 자연환기력 분석)

  • Lee, Chang-Woo;Park, Hong-Chae
    • Tunnel and Underground Space
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    • v.19 no.3
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    • pp.226-235
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    • 2009
  • Force induced by the natural ventilation in tunnel is likely to generate adverse influences on the airflow during the normal operation and create even more unfavorable circumstances during the tunnel fire. The influence of the natural ventilation is required to take into account in designing and operating the ventilation as well as safety systems. The magnitude of natural ventilation force depends on a variety of factors associated with the topographical, meteorological and physical features of tunnel. Unfortunately, at this moment those are difficult to quantify and none of the countries has suggested its estimation method in the design guideline. This study aims at quantifying the natural ventilation force at a local highway tunnel by three different methods. The first method employes direct measurement of the pressure at portals, while the second applies a stepwise approach to eliminate the piston effect ahead of deriving the natural ventilation force and the third method uses the concept of barometric barrier.

A case study for prediction of the natural ventilation force in a local long vehicle tunnel (장대도로터널의 자연환기력 예측 사례연구)

  • Lee, Chang-Woo;Kim, Sang-Hyun;Gil, Se-Won;Cho, Woo-Chul
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.11 no.4
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    • pp.395-401
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    • 2009
  • One of the key design factors for the ventilation and safety system at extra long tunnel is the airflow velocity induced by the natural ventilation force. Despite of the importance, it has not been widely studied due to the complicated influencing variables and the relationship among them is difficult to quantify. At this moment none of the countries in the world defines its specific value on verified ground. It is also the case in Korea. The recent worldwide disasters by tunnel fires and demands for better air quality inside tunnel by users require the optimization of the tunnel ventilation system. This indicates why the natural ventilation force is necessary to be thoroughly studied. This paper aims at predicting the natural ventilation force at a 11 km-long tunnel which is in the stage of detailed design and will be the longest vehicle tunnel in Korea. The concept of barometric barrier which can provide the maximum possible natural ventilation force generated by the topographic effect on the external wind is applied to estimate the effect of wind pressure and the chimney effect caused by the in and outside temperature difference is also analyzed.

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Characterization of deterioration of concrete lining in tunnel structures (터널 콘크리트 라이닝 구조물의 성능저하 특성)

  • Kim, Dong-Gyou;Jung, Ho-Seop;Bae, Gyu-Jin;Shin, Hyu-Soung
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.11 no.4
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    • pp.387-394
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    • 2009
  • The objective of this study is to evaluate the durability and deterioration of concrete lining in the seven conventional tunnels. These tunnels were constructed about 40~70 years ago, and closed about 10~40 years ago. The field investigation and various laboratory testings were performed for this study. It was observed from the visual, examinations that the concrete linings of 7 tunnels were severely deteriorated, such as, cracks, leakages, desquamation, and exploitations. The compressive strengths obtained from rebound hardness method and uniaxial compressive strength test on core specimens largely differed depending on the locations in the tunnel. The maximum compressive strength of concrete lining was greater about 2 times than the minimum compressive strength of concrete lining in the same tunnel. The results of micro-structural analysis showed that the substances deteriorating the concrete lining, such as ettringite and thaumasite, were detected in the concrete lining of tunnel.

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A study on applications of the natural ventilation pressure(NVP) in local tunnels (터널내 자연환기력(NVP) 적용방안 연구)

  • Kim, Hyo-Gyu;Yoo, Ji-Oh;Lee, Chang-Woo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.3
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    • pp.269-285
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    • 2014
  • In spite of the importance of the natural ventilation pressure(NVP) in tunnels for the optimal design of the ventilation system, there have been only few studies on the NVP because its measurement and quantitative analysis are not straightforward. This study aims at quantifying the amount of the NVP with the terrain and meteorological data for the local major tunnels. And ultimately this will lead to developing the guidelines for quantifying and applying NVP for the optimal design of tunnel ventilation system. 22 local tunnels in the major routes are studied for the NVP quantification. NVP derived from the meteorological data is in the range of 20~140 Pa, while NVP estimated from the terrain data ranges from 20 to 200 Pa. Since the jet fan pressure is about 10~15 Pa per unit, the minimum level of NVP expected in the local tunnels is larger than the pressure rise by one unit of the ordinary jet fan. This implies that NVP in local tunnels should be quantified and be taken into consideration for the economic and safe ventilation design. The barometric pressure difference between tunnel portals is found to be the most influential factor, accounting for 61% of the NVP, while the wind pressure acting on the portals and the chimney effects occupy 22% and 17%, respectively.