• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1994.03a
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• pp.12-23
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• 1994

터널의 방수형식은 배수형(Wet System)과 방수형(Dry System)으로 대별된다. 배수형은 터널의 아치부와 측벽부에만 방수막을 설치하고 이의 배면과 바닥으로부터 유입되는 지하수를 배수공을 통하여 배수처리하는 방식이며 경제성과 시공성이 우수하여 대부분의 도로 터널 및 지하철 등에 적용되어 왔다. 방수형은 터널의 주변장 전체를 방수시공하여 터널내로 유입되는 지하수를 완전히 차단하는 방법으로서, 이러한 방수형 터널은 경제성과 시공성은 불리하나, 지하수위 저하에 따른 압밀침하나 생태계 파괴 방지, 터널의 장기적 환경보전 및 운영유지비 감소 등의 이유로 최근 상당수의 도심지 지하철 터널에 계획되어 시공중에 있다. (중략)

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.973-984
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• 2017

There is a growing need to apply TBM tunnelling method for the construction of underground facilities such as subways and utility tunnels in urban areas. Due to the variability and uncertainty of the ground, tunnelling in urban areas has various safety hazards which could cause damage to people and properties and it is very costly to recover from accidents. Therefore, it is very important to identify hazards from the planning and design phase and to establish risk mitigation measures. In this study, a total of 31 hazards affecting the stability of TBM tunnelling works in urban areas were listed from both the technical literature and correspondence with experts in tunnelling area. The importance and priorities of the hazards were analyzed by conducting Delphi technique, which is a decision-making method by consensus among experts. Finally, 12 hazards that satisfy the content validity criteria were settled and could be used as major control factors for accident prevention during TBM tunnelling works.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.155-166
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• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.245-245
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• 2022

최근 국내 기후변화에 따른 국지성 집중호우로 인한 시간당 강우량의 증가로 도로부 유출량의 증가와 배수관거에서의 내수배제 불량에 따른 도심지 내수침수 피해가 증가함에 따라 이를 해결하기 위한 우수유출저감시설이 설치되고 있다. 그러나 대단위의 지하 저류시설의 지속적인 설치는 과밀화된 도심지에서 설치 지하공간의 구조적인 한계 및 적정 설치 위치의 미확보 등의 다양한 문제가 발생하여 저류시설의 침수저감 효과에 대한 추가적이고 새로운 저류시설에 대한 연구가 필요한 실정이다. 이에 내수 침수 저감 및 배수 능력 향상을 위한 도로 배수시설과 연계된 도로 측구부 저류시스템 구축이 필요하다. 이를 위해 역류 방지 및 노면수 저류 빗물받이에 적용되는 부력식 역류차단장치를 개발하였으며, 역류차단장치의 최적 형상 개발을 위해서 기존 빗물받이 연결관과의 통수능 비교 및 분석이 필요한 실정이다. 따라서 본 연구에서는 기존 빗물받이 연결관 및 연결관 내에 역류차단장치가 적용된 역류차단 빗물받이의 흐름분석을 위해 Fluent 모형을 이용하여 3차원 수치모의를 수행하였다. 수치모의 구성으로는 전체 형상을 40×50cm의 빗물받이 유입부와 50×50cm의 빗물받이로 결정하고 격자는 빗물받이 내부의 복잡한 3차원 흐름을 모의하기 위해 1.2~2mm 크기로 생성하였다. 다상유동 해석을 위해 VOF(Volume of Fluid)방법을 적용하였고, 수치해석 방법으로는 비정상류, 난류 모형으로는 SST k-𝜔모형을 적용하였다. 해석조건으로는 김정수(2021) 등이 제시한 4차선 기준 설계빈도별(5~30년) 빗물받이 유입유량을 산정하여 빗물받이 유입조건으로 선정하였으며, 빗물받이와 연결관에서의 통수능력 분석 조건으로는 빗물받이에 기존 연결관이 부착된 조건과 연결관 내에 역류차단장치가 설치되어 역류차단장치가 개방된 조건에서의 통수능을 비교하였으며, 역류상황을 가정한 연결관에서의 통수능을 비교하기 위하여 역류차단장치의 개폐정도를 15도(통수단면 33%감소) 닫힌 상태 및 30도(통수단면 67% 감소) 닫힌 상태 조건을 대상으로 빗물받이와 연결관에서의 흐름을 모의하였다. 수치모의 결과 역류차단장치의 계폐조건에 상관없이 5년 빈도유입량 조건에서는 완전 배수가 되었으며, 개폐조건 15도에서는 10년 빈도의 유입량에서는 완전 배수가 되었으나 20년 빈도 이상의 유입량 조건에서 빗물받이 유입부로의 역류가 발생하였으며, 개폐조건 30도에서는 5년 빈도 이상 유입량 조건에서 빗물받이 유입부로 역류가 발생하는 것으로 나타났다. 특히, 30년 빈도 이상의 유입량부터는 빗물받이 연결관 내에 역류차단장치 개페조건과 관계없이 빗물받이 유입부로의 역류로 인한 도로 침수가 발생하기 때문에 유휴공간인 도로 측구부를 저류공간으로 활용할 수 있는 도로 측구부 저류시스템의 구축은 필수적이라고 판단되며, 유량 조건에 따른 빗물받이 내부 와 흐름과 유출부에서의 유속 변화 특성을 확인하였다. 그러므로 측구 저류조 개발 형상과 연결한 3차원 흐름의 구현 및 분석에 Fluent 모형의 적용이 가능하다고 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.265-265
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• 2021

해수면 상승과 연안지역의 무분별한 지하수의 이용으로 해수침투는 가속화되고 있다. 해수면 상승과 지하수의 과잉 양수로 인한 연안지역의 대수층은 사용 가능한 담수 지하수자원이 줄어들고 있다. 연안지역의 대수층을 대상으로 해수 침투 영역에 미치는 영향에 대한 연구는 활발하게 진행되고 있다. GALDIT은 index & ranking 방법을 이용한 지하수자원의 해수침투에 대한 취약성 평가 방법으로 Geographic Information System (GIS)을 통해 주제도에 대한 중첩으로 평가 지수를 산정한다. 한국의 해수침투 취약성 평가에 대한 선행 연구 중 상당수는 제주도를 대상으로 많은 연구가 수행되었으며, GALDIT을 이용하여 해수침투에 대한 취약성 평가가 수행되었다. 본 연구에서는 내륙의 연안지역을 대상으로 GALDIT을 적용하였다. 한국의 서해안 지역 중 도심지가 밀집되어 있는 북쪽으로 선택하였다. 연구지역은 인천, 아산, 안산, 김포, 화성, 시흥, 평택, 당진, 오산으로 9개의 행정구역으로 구성되어 있다. 9개의 지역은 모두 제조업이 발달되어 도시화가 가속화되고 있으며, 지속적인 인구의 유입이 진행되고 있다. GALDIT은 지속가능한 해안지하수를 위한 수자원 계획을 뒷받침하는 평가 자료로 사용될 수 있으며, 국내 기후 및 공간 특성 매개변수를 고려한 가중치 및 평가 기준의 확대 등이 필요할 것으로 생각된다.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.77-87
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• 2021

Several studies have been conducted to analyze, predict, and prevent the risk of ground subsidence occurring in urban areas. Nevertheless, there is insufficient research effort on risk analysis that utilizes the correlation between the density of underground structures (i.e., the spatial quantity of buried objects installed in the ground around the interested area) and the occurrence of ground subsidence. In this paper, a study was conducted to analyze the line density of underground structures using GIS-based spatial information data, and to link this with the recorded ground subsidences. An optimization algorithm was developed to maximize the correlation between the line density of 29 recorded ground subsidences and 6 types of underground structures that occurred between 2010 and 2015 for the analysis area. The concept of normalized line density was also proposed for the analysis. The normalized line density of the analysis area was divided into five grades (Grade 1: lowest, Grade 5: highest). When the optimization algorithm was applied, the case where the normalized line density was Grade 4 or higher at the location of the recorded ground subsidences was about > 80%. It is thought that the density analysis result of underground facilities can be applied to the ground subsidence risk analysis by using the proposed optimization algorithm.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.69-77
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• 2022

Several studies have been conducted to analyze the risk of ground subsidence occurring in urban areas. Recently, the correlation between the density of underground utilities (i.e., the quantity of buried utilities in the analysis area) and the recorded ground subsidence has been explored to analyze such risk through. Choi et al. (2021) proposed an algorithm to optimize the correlation between the ground subsidence and normalized linear density of underground pipelines. In this study, the optimization algorithm was modified for analysis based on the risk grade. The analysis results using the modified optimization algorithm were compared with the correlation analysis results between the density of underground utilities and recorded ground subsidence presented by Choi et al. (2021). Compared with Choi et al. (2021), three analysis results showed equal or higher accuracy in the correlation analysis with recorded ground subsidence according to risk grade. In particular, for R100, it was divided into five grades and compared with the ratio of the recorded ground subsidence that occurred in grades 4 or higher. As a result, Choi et al. (2021) showed that 86% of recorded ground subsidence occurred in grades 4 or higher, whereas this study showed 93%. It was confirmed that the accuracy of the modified optimization algorithm was improved. The modified optimization algorithm can be applied to develop a ground subsidence risk map for each grade in an urban area, which can be used as basic data for decision-making for underground utility maintenance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.297-307
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• 2017

There are many underground spaces available in an urban environment and they represent an important factor for efficient land use. Especially, underground shopping centers perform both physical and commercial functions at the same time and are frequently used as a means of achieving the revitalization of the city center. However, the underground shopping centers that were developed in the past sometimes led to recession due to their deterioration. This study was carried out for the purpose of proposing alternative methods for the (revitalization) of underground shopping centers. A survey was conducted on seven underground shopping centers in the Busan metropolitan area to understand the factors that determine their user satisfaction and future improvement. The survey data was analyzed using an ordered logit model. As a result of the analysis, service satisfaction, underground environment satisfaction and public facility satisfaction were selected as significant variables. It was concluded that it is necessary to take these factors into consideration, appropriately, when developing a new or renewing an existing underground shopping mall.

• Journal of the Korean GEO-environmental Society
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• v.24 no.4
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• pp.23-29
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• 2023

Ground subsidence shows a mechanism in which the upper ground collapses due to the formation of a cavity due to the movement of soil particles in the ground due to the formation of a waterway because of damage to the water supply/sewer pipes. As a result, cavity is created in the ground and the upper ground is collapsing. Therefore, ground subsidence frequently occurs mainly in downtown areas where a large amount of underground facilities are buried. Accordingly, research to predict the risk of ground subsidence is continuously being conducted. This study tried to present a ground subsidence risk prediction model for two districts of ○○ city. After constructing a data set and performing preprocessing, using the property data of underground facilities in the target area (year of service, pipe diameter), density of underground facilities, and ground subsidence history data. By applying the dataset to the machine learning model, it is evaluated the reliability of the selected model and the importance of the influencing factors used in predicting the ground subsidence risk derived from the model is presented.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.19-32
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• 2011

The risk assessment is essential for tunnel design in order to minimize risks associated with uncertainty about geological conditions and tunneling method. This paper provides a comparative risk analysis of a large single bore TBM driven tunnel against sequentially excavated NATM tunnel for a mixed-face large-diameter urban tunnel project near or under a river. The focus of this assessment is on the risks associated with the tunnel excavation methods, in particular whether a TBM or NATM presents more or less risk to achieve the planned excavation duration and bring the project within the estimated bid price. First, the impacts and risks to tunnel construction under each method were discussed, and the risks were scored and ranked in the order of perceived severity and likelihood. Finally, the assessment from a risk based perspective was conducted to decide which alternate tunneling method is more likely to deliver the project with the least time and cost. It is very important to note that this study is only applied to this tunnel project with specific geological conditions and other contract requirements.