• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.23-24
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• 2022

There are many demands for vertical extension construction method in domestic large cities. In this paper, we analyzed and presented the results of examining the cases of ground floor extension and basement extension using the jack pile method. Since the Jack Pile method presses in all the piles without excavating the ground, the bearing capacity of the all the piles can be checked. It was investigated as a safe construction method unlike other small-diameter pile construction methods during underground extension.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.273-274
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• 2021

This paper proposes a process to calculate the amount of construction and demolition (C&D) of underground vertical extension methods through considering the characteristics of used construction and demolished materials. The underground vertical extension methods analyzed in this paper were the bottom-up, normal top-down, and top-down methods with multi-post downward (MPD). In order to check the applicability of the proposed process, 24 illustrative examples were generated. The amount of C&D waste of the illustrative examples were calculated and compared. As the results, the top-down method with MPD was the most efficient method to reduce the amount of C&D waste.

• Geomechanics and Engineering
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• 제5권2호
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• pp.99-118
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• 2013

Construction of the extension project of the Bangkok MRT Blue Line underground railway was recently started in 2011. The construction of approximately 5 km long underground tunnel and 4 deep excavations of underground station are considered to be the most important geotechnical works. The pressuremeter was selected as a high-quality in situ testing of the soil to evaluate design parameters for the project. In addition, other field and laboratory tests such as vane shear and $CK_0U$ triaxial tests were included in the investigation programme. This paper aims to present the ground conditions encountered along the MRT Blue Line extension project as well as the site investigation and interpretation techniques with particular focus on the pressuremeter tests. The results are also compared with the pressuremeter investigation from the previous Bangkok MRT project.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.254-255
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• 2013

New Seoul city hall completed in 1926 is a registered historical building. The remodeling plan has been developed for the expansion after the review by the governmental agency. Based on the plan, a new city hall should be constructed behind the current city hall while the facade, the main lobby and the dorm structure of the existing building, A new construction method, FUSEM, has been developed for this mission for the safety of the historical structure.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.736-741
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• 2005

This paper presents electric characteristics analysis and safe configuration for extension power supply between existent 6.6kV ungrounded distribution system and establishment and improvement 22.9kV direct grounding distribution system. For this, we model 6.6kV ungrounded and 22.9kV direct grounding distribution system of urban underground, ground region. and rural electrical, unelectrical region using PSCAD/EMTDC and analyze voltage drop, charging current, ground and short fault through simulation. To analyze electric characteristics of extension power supply, we simulate extension power supply of overhead line of 6.6kV ungrounded system and underground line of 22.9kV direct grounding system of rural electrical region and propose operation condition for safe extension power supply through result of analysis. Characteristics of voltage drop, charging current, ground and short fault appear almost similarly with electrical characteristic of direct power supply. However, because unbalance of phases may cause relay's malfunction of ungrounded system and ground fault current of direct grounding system may demage facilities of ungrounded system, we propose safe system configuration such as impedance grounding system of neutral point.

• 국제초고층학회논문집
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• 제10권1호
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• pp.17-28
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• 2021

In Harbin, a network of underground commercial spaces has been developed to occupy spaces that were originally created as civil defense shelters. With the gradual extension of the local metro rail system, the existing underground commercial space is no longer an isolated regional development, but a space that represents "three-dimensional city" and coordinated development taking place in many Chinese cities. Based on the analysis of the unique development process taken in underground space of Harbin, this paper summarizes three characteristics of its early model of "fragmented development" of underground space. By conducting a comprehensive field research and survey, the researchers analyzed 472 questionnaires related to the development trend, and proposed multi-level synergistic elements for the renewal and development of underground commercial space. The paper concludes by discussing the trend of "three-dimensional and collaborative development," suitable for the development needs of the new era, and the corresponding development strategies for the renewal of underground space.

• Geomechanics and Engineering
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• 제16권1호
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• pp.35-47
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• 2018

This paper investigates the mechanisms of tunnel spalling and massive tunnel failures using fracture mechanics principles. The study starts with examining the fracture propagation due to tensile and shear failure mechanisms. It was found that, fundamentally, in rock masses with high compressive stresses, tensile fracture propagation is often a stable process which leads to a gradual failure. Shear fracture propagation tends to be an unstable process. Several real case observations of spalling failures and massive shear failures in boreholes, tunnels and underground roadways are shown in the paper. A number of numerical models were used to investigate the fracture mechanisms and extents in the roof/wall of a deep tunnel and in an underground coal mine roadway. The modelling was done using a unique fracture mechanics code FRACOD which simulates explicitly the fracture initiation and propagation process. The study has demonstrated that both tensile and shear fracturing may occur in the vicinity of an underground opening. Shallow spalling in the tunnel wall is believed to be caused by tensile fracturing from extensional strain although no tensile stress exists there. Massive large scale failure however is most likely to be caused by shear fracturing under high compressive stresses. The observation that tunnel spalling often starts when the hoop stress reaches $0.4^*UCS$ has been explained in this paper by using the extension strain criterion. At this uniaxial compressive stress level, the lateral extensional strain is equivalent to the critical strain under uniaxial tension. Scale effect on UCS commonly believed by many is unlikely the dominant factor in this phenomenon.

• 교육시설 논문지
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• 제24권1호
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• pp.3-10
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• 2017

This study is to analyze the remodeling method of library in terms of space extension method and urban regeneration by repurposing function in unused facilities through case study. In many case of library extension, horizontal extensions are more frequent than vertical extensions, because there are limits to extend vertically due to high live load estimation by book stacks. Extension schemes was organized by new building extension method in connection with existing buildings, attaching method small scaled mass or linear mass to existing building, connecting method a plurality of existing small buildings, vertical extension method on the top of the structure, underground extension method using special structure. Unused facility remodeling to the library, large scaled buildings can be developed completely to the function of the library through the relocation of the space, while small scaled building needs spatial extension. In the case of spatial extension, existing space that was used for other purposes can be used as a reading room or office, avoiding high live load estimation.

• 한국지반환경공학회 논문집
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• 제21권8호
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• pp.5-13
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• 2020

노후시설물의 지하공간 확장공사 시 공사 중 소음 및 진동 문제 뿐만 아니라 기존 주민의 임시 거주공간 확보가 필요하고, 상업용, 공업용, 사회용 등의 시설물의 경우에는 시설물 이용의 중단에 따른 피해가 예상되므로, 지하증축 공사 중 소음 및 진동을 최소화하여 공사 중에도 기존 시설물의 이용을 가능하게 하는 기술이 필요하다. 따라서 본 연구에서는 가설구조물의 안정성 문제와 공사 중 발생되는 소음진동 문제를 효과적으로 해결하여 지하증축 공사 중 시설물을 이용하면서 진행한 공사현장의 시공단계별 계측결과로 가설구조물과 주변지반의 거동을 분석하여 국내 현실에 적합한 지하증축공사 모델을 제시하였다. 시공 시 발생되는 문제를 해결하기 위해 초기 굴착 후 슬라브 선타설공법을 적용한 현장의 계측결과(건물경사계, 균열측정계, 구조물경사계, 지표침하계)를 확인한 결과 건물경사계와 구조물경사계는 슬라브 선타설후 변위가 감소하거나 수렴하는 경향을 확인할 수 있었으며, 균열측정계와 지표침하계는 관리기준 이내의 안정적인 모습을 확인할 수 있었다. 이 결과로 볼 때, 지하증축 공사 시 지하층 슬라브를 선타설하는 것은 공사 중 발생하는 소음·진동의 문제를 해결해주는 것 뿐만 아니라 지하증축 공사 시 가설구조물의 안정성을 확보하는데 큰 역할하고 있는 것을 확인할 수 있었다.

• 터널과지하공간
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• 제9권2호
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• pp.149-157
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• 1999

불연속 변형 해석법(Discontinuous Deformation Analysis Method)은 1988년에 Shi에 의해 개발되었으며, 암반-구조물 상호작용 모델링에 매우 효율적인 해석법이다. 이 해석법에서 암반은 유한하고 변형가능한 블록으로 간주되며, 암반의 대변형 및 이동이 가능하다. 그 후, DDA 방법에 대한 여러가지 보완사례가 발표되었으나, 균열이 발달한 암반의 지표 또는 지중 굴착 모델링에 긴요한 지하수-암반블록 상호작용 모델링은 불가능하다. 본 논문에서는 암반 블록 사이의 수리 력학적 커플링을 고려하기 위한 새로운 방법이 제시된다. 또한, 이 방법이 보완된 새로운 DDA해석법의 적용 예가 제시된다. 본 연구결과 암반 균열 사이를 흐르는 지하수는 터널의 안정성에 나쁜 영향을 미친다는 사실이 확인되었다.