• Title, Summary, Keyword: Tunnel station excavation

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Study on Ground Surface settlement of a 3-Arch-shaped Tunnel (3아치터널의 지표면 침하에 관한 연구)

  • Shin Kang Ho;Park Tu Sung;Park O Sung;Kim Jae Kwon
    • Proceedings of the KSR Conference
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    • pp.1007-1013
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    • 2004
  • A three-arch NATM tunnel with a total length of 53.5m has been constructed for a metropolitan subway station in Daejon, Korea. The tunnel, whose crown is located 22m below the ground, crosses the old Daejon station underneath. Since the tunnel comprises a very large section (10${\times}$28 m; largest in Korea), it shows complicated mechanical behaviors, especially near portal, due to its short length relative to width. As far as its construction step is concerned, the center tunnel is excavated with pre-excavated pilot tunnel, which is a unique feature of this tunnel (first in Korea) to secure safety during construction and prevent excessive settlements. The both side tunnels are then excavated along with the center tunnel. Since significant amount of settlement was predictable from the design stage, extensive monitoring was performed during construction. During excavation of the side tunnels, unexpected large settlements up to ${\~}$140mm (estimated 41.8 mm at design stage) was measured at the center tunnel. In this paper, we study the causes of this unusually large ground settlement. We believe that the extra-wide tunnel excavation increases the stress influence zone of portal in longitudinal direction and consequently add more settlements to the existing due to excavation and consolidation.

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Analysis of Effect of Railway Tunnel Excavation on Water Levels of a National Groundwater Monitoring Station in Mokpo, Korea (철도 터널 굴착이 목포용당 국가 지하수 관측소 지하수위에 미친 영향 분석)

  • Lee Jin-Yong;Yi Myeong-Jae;Choi Mi-Jung;Hwang Hyoun-Tae;Moon Sang-Ho;Won Jong-Ho
    • Tunnel and Underground Space
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    • v.16 no.1
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    • pp.73-84
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    • 2006
  • Effects of railway tunnel excavation on water level at a national groundwater monitoring station in Mokpo were evaluated by field investigation and numerical groundwater modeling. The water level at the station has experienced a decline of about 5 m within 1 year since July 2002. From the field investigation, it was concluded that decrease of precipitation oo increase of grundwater use was not reason for the decline. The Mokpo tunnel of new Honam railway, 70 m apart from the national station, appeared most plausible cause and a period of the tunnel excavation generally well matches up that of the drawdown. To quantify the effects of the tunneling on the water level, a groundwater flow modeling was performed. Especially, a most probable conceptual model was optimized through multiple preliminary simulations of various scenarios because there were few hydrogeological data available for the study area. The optimized model was finally used for the quantification. Based on the field investigation and the numerical simulations, it was concluded that the tunnel excavation was one of the most probable reasons for the substantial water level decline but further hydrogeologic investigation and continuous monitoring are essentially required for the surrounding area.

Design and Construction of a Large Section Tunnel for a Subway Station (지하철 대단면 터널의 설계와 시공관리 사례)

  • 문상조;장석부;정준화
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.285-292
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    • 1999
  • Recent development cases of transportation utilities using tunnelling method in metropolitan sites have been increased due to the heavily complex environments and restrictions of construction works. The progress of tunnel design and construction to be supported by the tunnel analysis and measurement techniques using computers have increased adoptions of large section tunnels. In this paper, many factors to be considered in designing large section tunnels are discussed and the case of the construction of the subway station tunnel which is recently completed is introduced. This tunnel has a width of 24 m, a height of 16 m, and a excavation section area of 366 ㎡.

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Investigation of ground behaviour between plane-strain grouped pile and 2-arch tunnel station excavation (2-arch 터널 정거장 굴착 시 평면변형률 조건에서 군말뚝의 이격거리에 따른 지반거동 분석)

  • Kong, Suk-Min;Oh, Dong-Wook;Ahn, Ho-Yeon;Lee, Hyun-Gu;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.6
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    • pp.535-544
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    • 2016
  • Special tunnel design and construction methods have been suggested due to developments of subway and tunnel. Collapse accidents of tunnel bring enormous damage. So, observation and analysis for the safety of tunnelling and behaviour of surrounding ground are important. But, it is not economical to implement the field test in every time. Therefore, this study has measured ground behaviour due to excavation of 2-arch tunnel station according to offset between grouped pile and tunnel by laboratory model test. For the model test, trapdoor device was adopted. Tunnelling is simulated by volume loss of 2-arch tunnel. Ground displacements are observed by close range photogrammetric method and image processing. In addition, these data are compared with numerical analysis.

Application of Scanning Total Station for Efficiency Enhancement of Tunnel Surveys (터널측량의 효율성 향상을 위한 스캐닝 토털스테이션의 활용)

  • Park, Joon-Kyu;Kim, Min-Gyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.4
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    • pp.242-247
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    • 2017
  • Over- and under-excavation are factors that increase construction cost of tunnels, which makes management essential. Total stations have been used for tunnel surveying because GNSS is difficult to use in tunnels. However, it takes much time to acquire data using total stations. In this study, a total station was integrated with a 3D laser scanner and used for tunnel surveying in Namyangju-si, Gyeonggi-do. The scanning total station reduced the work time compared to the conventional method. Furthermore, reports were effectively generated for overbreak and underbreak for each section and compared with the design. In addition, we could analyze both the cross section and scanned area effectively by using the scanning data. This method can improve the efficiency of tunnel surveying work by combining the advantages of a conventional total station and a 3D laser scanner.

Investigation of soil behaviour due to excavation below the grouped pile according to shape of tunnel station (터널 정거장 형상에 따른 군말뚝 하부 굴착 시 지반거동 연구)

  • Kong, Suk-Min;Oh, Dong-Wook;Lee, Jong-Hyen;Lee, Yong-Joo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.1
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    • pp.83-97
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    • 2018
  • Tunnels are widely used for special purposes including roads, railways and culvert for power transmission, etc. Its cross-section shape is determined by uses, ground condition, environmental or economic factor. Many papers with respect to behaviours of adjacent ground and existing structure tunnelling-induced have been published by many researchers, but tunnel cross-section have rarely been considered. A collapse of tunnel causes vaster human and property damage than structures on the ground. Thus, it is very important to understand and analyse the relationship between behavoiurs of ground and cross-section type of tunnel. In this study, the behaviour of ground due to tunnel excavation for underground station below the grouped pile supported existing structure was analysed through laboratory model test using a trap-door device. Not only two cross-section types, 2-arch and box, as station for tunnel, but also, offset between tunnel and grouped pile centre (0.1B, 0.25B, 0.4B) are considered as variable of this study. In order to measure underground deformation tunnelling-induced, Close Range Photogrammetry technique was applied with laboratory model test, and results are compared to numerical analysis.

The stability analysis on large sectional tunnel station considering construction steps (시공단계를 고려한 대단면 정거장 터널 안정성 해석)

  • Kang, Eun-Gu;Kim, Yang-Woon;Ahn, Kyeong-Cheol;Han, Myeong-Sik
    • Proceedings of the KSR Conference
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    • pp.1062-1068
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    • 2009
  • Urban construction has numerous difficulties due to ground weakness and various complaints from third party, so it is not economically efficient and constructability is not favorable. Therefore, underground, which has good ground conditions, was used for construction field and facilities such as stations, and they are scaled up to enhance accommodation of facility limitation and function of stations. Large section tunnel station construction has numerous risk factors such as work boundary of excavation equipment, a relaxation of stress concentration, a safety plan of tunnel stability, and so on. Therefore, by using large section tunnel station stability analysis considering construction step, we expect to analyze the latent problem during construction, and to stabilize a future project plan of a large section structure design by using an auxiliary method and a support design.

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The main considerations in the design and safety assessment case study for Deep & Large size of Tunnel station (대심도 대단면 터널정거장 설계시 주요고려사항 및 안정성 평가에 대한 사례 연구)

  • Jang, Sun-Jong;Hong, Jong-Wan;Jeon, Ki-Chan;Kim, Young-Min;Paik, Jin-Wook
    • Proceedings of the KSR Conference
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    • pp.462-469
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    • 2011
  • The design of high-depth and large-section tunnel facilities has been increased lately. The purpose of the design is to avoid inference of existing facilities, enhance public relations and reducing the size of the station, which is advantageous for effective use of underground spaces. Diverse downtown tunnel experience, advanced excavation equipment, reinforcement methods, monitoring technologies and numerical analysis made the design possible. This paper is to introduce the design of high-depth and large-section tunnel facilities via Gimpo airport area of Deagok-Sosa railway BTL project of double-tracking.

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Analysis of accidents due to Urban Ground Excavation (지반굴착공사로 인한 사고사례 분석)

  • Seong, Joo-Hyun;Yoon, Jong-Ku;Jung, Soo-Hyung
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1087-1094
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    • 2010
  • With recent growth of population and industry, urban development grows into grand scheme of excavation and construction in urban area. As the development progress advanced, the developments get large and deepen. With a progress of technology development in geotechnical engineering in Korea, most our grand scheme of projects follows great progress. On the other hand, some excavation in construction site caused direct or indirect event that affects the adjacent or surrounding structures by excavation from time to time. This event usually happens around residential and commercial area where underground tunnel, subway station, commercial building, and high-rises excavation site is, could lead great damage on economy as well as personal injury or human casualties. In order to prevent this event, the study has to be done with analysis on various events of excavation and its cause. In this paper, the research has collected the various excavation events and their causes to analyze on each site and event to define emphasis on surrounding environment.

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perforation of tunnel in limestone formation (석회암층의 터널관통사례)

  • Kim, Yong-Il;Hwang, Nak-Yeon;Jeong, Du-Seok;Hong, Jong-Sang;Lee, Nae-Yong
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.64-80
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    • 2007
  • This paper presents a case study on the excavation of a long tunnel(16.2km) named as "Sol-An tunnel", which connects between Mt. Dongbaek station and Dokye station in the Young-dong Railroad. This site is located in a complex geological region with faults, cavities and coal measures as sedimentary rocks area. It occurred geotechnical problems unexpectedly by running water when tunnelling in limestone area within those geological structures. This tunnel caused surface settlements through the decrease of ground water level and soil washed-out affecting by cavities and faults within limestone formation. This paper presents a analysis of source through a close investigation and measures. And also, does preventive measures about returns of settlements reflected by properties of limestones.

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