• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1666-1672
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• 2008

In this study, it collected and analyzed a construction case of the improved top-down support system application field on a case by case retaining wall method. The behavior of horizontal displacement was analyzed according to retaining wall type after reviewing a design stage and estimated horizontal displacement under the construction. The study results showed that it is judged stable until excavation termination irrelevant to a retaining wall method at the improved top-down support system application. It is judged that the settlement of behind ground can minimize because the retaining wall head displacement also behave stably. It was compared the predicted horizontal displacement in design and the measured horizontal displacement acquired through a measurement by using Elasto-Plastic analysis program. The comparison results showed that a similar horizontal displacement was predicted within stability standard irrelevant to a retaining wall method. So, it is decided that the advanced prediction is reasonable by Elasto-Plastic analysis in design applied the improved top-down support system. In the case of the ground anchor method application under a same condition, it is decided that a horizontal displacement will more increase than the improved top-down support system is applied. If a section condition is same, it was decided that to apply top-down support system is more stable than that.

• 한국산학기술학회논문지
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• 제18권7호
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• pp.9-16
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• 2017

콘크리트 충전 강관 기둥을 개선한 팔각 콘크리트 충전 강관 기둥 (OCFT 기둥)이 개발되었다. 본 연구에서는 시공성 및 경제성 측면에서 장점을 갖는 OCFT 기둥을 역타(Top-Down) 공법에 적용하기 위하여 원심모형실험 장비를 활용하여 압축성능을 검증하였다. 12 g의 원심가속도가 작용하는 상태에서 말뚝으로 시공된 OCFT 기둥의 시공하중에 대한 지지가능 여부와 토사가 굴토되었을 경우 말뚝의 좌굴안전성 등을 관찰하기 위하여 압축강도에 대한 실험을 수행하였다. 천공 후, OCFT 기둥과 H 형강이 말뚝기초로 시공되고 뒷채움으로, 지반에 완전히 묻힌 실험체의 경우와 반만 묻힌 경우에 대하여, 약 13,000 kN의 공칭강도의 45% 시공하중을 재하한 결과 모든 실험체가 탄성상태에서 거동하였다. 하중재하실험 종료 후, 풍화암과 말뚝하부를 관찰한 결과 풍화암이 손상되지 않았으며, 이로부터 3.5 MPa 조성된 풍화암은 $600{\times}600mm$ OCFT 기둥의 공칭강도의 45%도 안정적으로 지지할 수 있는 것으로 판단된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술논문발표회
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• pp.37-40
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• 2002

The purpose of this study is promote perfect of construction and progress of packing ability through comparison and analysis with quality, as placing ways and placing direction are changed. Kinds of concrete are general, high fluidity, and high Performance concrete. Classified with concrete as placing ways - direct ways, sheath way - and placing directing - flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method.

• 한국지반신소재학회논문집
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• 제11권1호
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• pp.11-21
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• 2012

본 연구에서는 지중연속벽 설계시 사용되는 범용 해석프로그램에 Rankin(1857)의 이론토압과 홍원표와 윤중만(1995a)의 경험토압을 각각 적용하여 Top-Down 공법에 적용된 지중연속벽의 수평변위를 분석하였다. 그리고 이들 해석 프로그램에서 산정된 예측변위량과 지중경사계로 측정된 실측변위량을 비교 검토하였다. 현재 지중연속벽 설계에 적용되는 해석프로그램에는 Rankine의 토압이 주로 적용되고 있다. 검토결과, 지중연속벽의 예측수평변위는 적용되는 토압에 따라 상당히 큰 차이를 나타내고 있다. Rankine의 토압을 적용하여 산정된 예측수평변위 형상은 실측결과와 큰 차이를 보이고 있으며 벽체의 하부에서 예측치가 실측치보다 과다하게 산정되었다. 반면, 홍원표 윤중만의 토압을 적용하여 얻은 예측수평변위 형상과 최대수평변위량은 실측결과와 유사하게 나타났다. 따라서 Top-Down 공법이 적용된 지중연속벽의 설계시 Rankine의 토압보다는 홍원표 윤중만의 경험토압을 적용하는 것이 적합함을 알 수 있다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.808-813
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• 2009

Top-down method is widely used for urban area construction for its advantages in reducing environmental problems such as dust and noise, and saving construction cost depending on given conditions of a construction site. Because the excavation and construction of super- and sub-structures of the building have to be proceeded simultaneously, a column has to be embedded prior to excavation. This column is called a pillar column or pre-founded column. Usually a wide flange section is used for these columns. To place the columns, usually the diameter of casing holes needs to be larger than the section of the wide flange itself in order to accommodate a couple of tremie pipes for pouring concrete. In this paper, a newly developed method of using circular pipe as an alternative to the existing wide flange section is discussed. The crucial part of the new method is to develop a connection between the circular column and concrete flat slabs. For shear force transfer from concrete slab to the concrete filled tube (CFT) column, shear jackets with studs and shear bands are proposed. The studs are welded on the jackets at shop and placed around the circular column on site. The shear bands are welded on the outer side of the CFT at shop and inserted into ground with the CFT. Test results and application of the method to a construction site are also provided in this paper.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.763-768
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• 2001

The purpose of this study is to research a specific material characteristics of top down concrete at column joint and to reduce column joint opening. Based on the established top down study, the experiment to apply an real construction case is performed. When the concrete placed into joint of top down column, raised air bubble is left as opening. This study is examined the incomplete packing reason in the top down column and found to air deflation method. The result of study is below (1) As the method to minimize column opening caused from confined air, it is required that an air exhaust port installation in joint column. (2) From air exhaust port installation, most of air bubble in column part is exhausted. As the concrete placing height is going up, air bubble size is going smaller.

• 한국지반환경공학회 논문집
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• 제14권9호
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• pp.5-12
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• 2013

이 논문에서는 정재하시험과 양방향재하시험의 하중-침하거동을 비교하기 위하여 인접한 위치에서 직경 480mm인 암반에 소켓된 현장타설말뚝을 시공하고 각각 정재하시험과 양방향재하시험을 실시하였다. 양방향재하시험 해석법 중 기존의 탄성압축량을 고려하지 않은 등가하중곡선법은 정재하시험 결과와 비교할 경우 침하량을 과소평가하는 것으로 나타났기 때문에, 정확한 하중-침하 곡선 산정을 위해서는 반드시 탄성압축량을 고려해야 한다. 또한 기 제안된 여러 탄성압축량을 고려한 등가하중곡선법들을 정재하시험 결과와 비교검토한 결과, 충분한 적용성을 가지는 것으로 판단되었다. 또한 정재하시험과 양방향재하시험의 지지력을 비교한 결과, 양방향재하시험은 말뚝재료의 극한강도를 반영하지 못하고 지반의 극한지지력만을 평가하므로 반드시 재료강도에 대한 검토를 실시하여야 한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1107-1112
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• 2000

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is finding a way to prevent concrete void and concrete suitable for top down, through V-metering for top down column and concrete experiment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1101-1106
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• 2000

When top down method is used, it could be a construction method trouble in column joint, between the former concrete and the latter. It could bring a void and weak concrete in column. The purpose of this study is to find a solution of removing void and air, way to exhaust air in top down column. through specimen concrete placing experiment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.339-340
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• 2023

Steel construction is one of the commonly used methods in building construction due to its efficiency in terms of time and cost. In particular, the top-down method using steel frames is widely used in the construction of underground structures in urban areas to shorten the construction period. However, there is currently no standardized cost estimation for subway steel frame construction in Korea, causing difficulties in determining the expected cost. In this study, we aim to provide basic data for establishing a cost estimation standard for subway steel frame construction through on-site surveys of subway steel frame construction commonly used in urban areas.