• Title/Summary/Keyword: Large tunnel

Search Result 11, Processing Time 0.107 seconds

The Construction of large and Long Tunnel Using Bulk Explosives (벌크폭약을 이용한 대단면 장대터널 시공 사례)

  • 노상림;문상호;조영천;이상필;유지영
    • Explosives and Blasting
    • /
    • v.22 no.3
    • /
    • pp.65-70
    • /
    • 2004
  • Lately, the length of tunnel, the number of long-large tunnel over 3 lanes are steeply increased because of the request for high-speed and straight road. Therefore, the maximization of excavation efficiency is needed in tunnel construction. The sapaesan tunnel (4 lanes with the length of 4km) construction was delayed with environmental conflict far 2 years. For making-up delayed construction period, various new methods were adopted to improve excavation length, look-out and blasting efficiency. This study introduced bulk explosive which is new method in tunnel blasting and verified the efficiency of bulk explosive far long-large tunnel.

Magnetic Tunnel Junctions with Magnesium Oxide Barriers

  • Nagahama Taro;Moodera Jagadeesh S.
    • Journal of Magnetics
    • /
    • v.11 no.4
    • /
    • pp.170-181
    • /
    • 2006
  • Spin dependent tunneling has enormously activated the field of magnetism in general, and in particular spin transport studies, in the past ten years. Thousands of articles related to the subject have appeared with many fundamental results. Importantly, there is great interest in their potential for application. There was another surge of activity in this field since the past five years - created by the theoretical prediction of a large tunnel magnetoresistance that arises due to band symmetry matched coherent tunneling in epitaxial magnetic tunnel junctions with (001) MgO barrier and experimentally well demonstrated. This further development in the field has boosted the excitement in both fundamental science as well as the possibility of application in such as magnetic random access memory, ultra sensitive read heads, biosensors and spin torque diodes. This review is a brief coverage of the field highlighting the literature that deals with magnetic tunnel junctions having epitaxial MgO tunnel barriers.

Wind Tunnel Testing for Smart Unmanned Aerial Vehicle (스마트 무인기 풍동시험)

  • Chung, Jin-Deog;Choi, Sung-Wook;Lee, Jang-Yeoun
    • 유체기계공업학회:학술대회논문집
    • /
    • /
    • pp.37-40
    • /
    • 2006
  • Wind tunnel testings to develope tilt-rotor Smart Unmanned Aerial Vehicle (SUAV) were intensively performed. Small wind tunnel was used to find and evaluate design parameters and to fix general layout of configuration. The application of large tunnel with 40% scaled model is to collect performance and stability related aerodynamic data. During large scale model test wind tunnel is used as a tool to compare Flaperon types, to improve lift characteristics by using different height vortex generators and to alleviate nacelle separated flow effects on the wing.

  • PDF

A case study of large - long tunnel using the charging mechanization system of the bulk emulsion explosives (Bulk Emulsion 기계화 장전시스템을 이용한 대단면 장대터널 시공사례연구)

  • Yoon, Ji-Sun;Jang, Young-Min;Lee, Sang-Hun
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.11 no.2
    • /
    • pp.107-115
    • /
    • 2009
  • Lately, the length of tunnel, the number of large-long tunnel over three lanes are steeply increased because of the request for high speed and straight road. Therefore, the maximization of excavation efficiency is needed in tunnel construction. Bulk Emulsion explosives charging system is the spearhead equipment using the radio remote control $&$ mechanization system compare with a traditional method Cartridge type. This study introduced the bulk emulsion explosives which is new method in tunnel blasting and verified the efficiency of bulk emulsion explosives for long-large tunnel. And we tried to compare Cartridge type efficiency with bulk emulsion explosives efficiency by the field test.

  • PDF

Review of Mechanical Behaviors of Pillar in Large Parallel Tunnel (대단면 근접병설터널에서의 필러부 거동특성 검토)

  • Sin, Young-Wan;Kim, Young-Geun
    • Tunnel and Underground Space
    • /
    • v.20 no.3
    • /
    • pp.131-144
    • /
    • 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.

Stability analysis of a 2 arch tunnel considering excavation sequence (굴착단계를 고려한 2 아치 터널의 안정성 해석)

  • You, Kwang-Ho;Park, Yeon-Jun
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.4 no.2
    • /
    • pp.167-174
    • /
    • 2002
  • In this study, a numerical stability analysis was performed for a large tunnel considering excavation sequence. In most cases, stability of a tunnel is analyzed based on the stability of the final excavation stage only. In this study, stability analysis of a tunnel was performed at each excavation stage. In summary, it can be inferred that there is no problem in stability of the tunnel. However, thorough and careful measurements are recommended. Also, it is found that the stability of the tunnel at the 5th excavation stage when the right half of the main tunnel is excavated is rather lower than that of the tunnel at the final excavation stage.

  • PDF

Assessment of minimum pillar width and reinforcement of parallel tunnel using numerical analysis and field monitoring (수치해석과 현장계측을 통한 병렬터널의 최소 필라폭과 보강에 대한 평가)

  • An, Yong-Koan;Kong, Suk-Min;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.16 no.3
    • /
    • pp.299-310
    • /
    • 2014
  • Nationally, tunnel and underground constructions are necessary for the environmental sustainability and the efficient use of land space. For the importance of eco-friendly circumstances, 2-arch or large road tunnel has been designed so far. However, such a 2-arch or large tunnel has problems in terms of cost, constructability, construction period, and maintenance. Therefore, in this study, tunnel behavior and stability of rock pillar according to the pillar width and cover depth for parallel tunnels are investigated by performing FE analysis and using empirical formula. According to the results, Rock pillar is reinforced for distributed vertical load by Tie-Bolt due to unpredicted ground deformation, and the reinforced rock pillar's behaviour from the FE analysis shows a quite good agreement with field measurement. According to ground conditions, if the pillar width of the parallel tunnels is reduced, it can be more efficient in use of the tunnel space compared to previous tunnels.

Prediction of transverse settlement trough considering the combined effects of excavation and groundwater depression

  • Kim, Jonguk;Kim, Jungjoo;Lee, Jaekook;Yoo, Hankyu
    • Geomechanics and Engineering
    • /
    • v.15 no.3
    • /
    • pp.851-859
    • /
    • 2018
  • There are two primary causes of the ground movement due to tunnelling in urban areas; firstly the lost ground and secondly the groundwater depression during construction. The groundwater depression was usually not considered as a cause of settlement in previous research works. The main purpose of this study is to analyze the combined effect of these two phenomena on the transverse settlement trough. Centrifuge model tests and numerical analysis were primarily selected as the methodology. The characteristics of settlement trough were analyzed by performing centrifuge model tests where acceleration reached up to 80g condition. Two different types of tunnel models of 180 mm diameter were prepared in order to match the prototype of a large tunnel of 14.4 m diameter. A volume loss model was made to simulate the excavation procedure at different volume loss and a drainage tunnel model was made to simulate the reduction in pore pressure distribution. Numerical analysis was performed using FLAC 2D program in order to analyze the effects of various groundwater depression values on the settlement trough. Unconfined fluid flow condition was selected to develop the phreatic surface and groundwater level on the surface. The settlement troughs obtained in the results were investigated according to the combined effect of excavation and groundwater depression. Subsequently, a new curve is suggested to consider elastic settlement in the modified Gaussian curve. The results show that the effects of groundwater depression are considerable as the settlement trough gets deeper and wider compared to the trough obtained only due to excavation. The relationships of maximum settlement and infection point with the reduced pore pressure at tunnel centerline are also suggested.

A study on the stability analysis for double deck tunnel branch geometry (복층터널 분기 기하구조에 따른 안정성 검토에 관한 연구)

  • Park, Woo-Jeong;Jang, Namju;Kim, Kihwan;Choi, Chang-rim
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.20 no.2
    • /
    • pp.393-404
    • /
    • 2018
  • The tunnel can be planned to connect to underground roadway and surface road. The large tunnel and branch section are made when the ramp tunnel access to the main tunnel. In the branch section, stress concentration can be assigned and it can be very important for the stability of the tunnel. This study assessed the behavior of rock pillar in double deck tunnel diverging area by using a two dimensional numerical analysis. This study evaluated different safety factors according to pillar width and the ramp tunnel position in branch. By the assessment of the strength-stress ratio, tunnel pillar width is suggested in order to secure the safety factor 1.5.

A comparative study on the stability evaluation of double deck tunnel in terms of excavation (대심도 복층터널에 대한 굴착 안정성 평가 비교 연구)

  • Jang, Namju;Gang, Han-gil;Kim, Kihwan;Choi, Chang-rim
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.21 no.1
    • /
    • pp.155-166
    • /
    • 2019
  • It is necessary to construct underground in the metropolis. Road traffic has reached saturation point. The city has several underground road construction projects. In abroad, double deck tunnels are planned and constructed. It is attained a high level of underground development technology. In case the double deck tunnel (2 lane) is planed instead of the bidirectional tunnel (2 lane), excavation area is similar. But tunnel width is decreased. The reduced width can cut cost for the tunnel reinforcement. This study evaluates the stability of excavation on double deck tunnel. By the assessment of the strength-stress ratio and strength reduction method, quantitative analysis is conducted between double deck tunnel and the bidirectional tunnel.