• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.143-154
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• 2016

This study investigated the occurrences, causes, and mitigation of the recent ground subsidence and underground cavity generation events in Korea. Two main causes of ground subsidence are (1) the soil erosion by seepage during tunneling and earth excavation and (2) the damage of underground pipes. The main cause of the soil erosion during tunneling was the uncontrolled groundwater flow. Especially, when excavating soft grounds using a tunnel boring machine (TBM), the ground near TBM operation halt points were found to be the most vulnerable to failure. The damage of underground pipes was mainly caused by poor construction, material deterioration, and differential settlement in soft soils. The ground subsidence during tunneling and earth excavation can be managed by monitoring the outflow of groundwater and eroded soils in construction sites. It is expected that the ground subsidence by the underground pipe damage can be managed or mitigated by life cycle analysis and maintenance of the buried pipes, and by controlling the earth pressure distribution or increasing the bearing capacity at the upper ground of the buried pipes.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.546-549
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• 2007

지열 냉난방 시스템의 설계는 냉난방 공간의 크기에 따라 필요한 부하를 계산하여 설계하게된 다. 설계 부하를 충분히 소화할 수 있는 지열교환기의 길이와 보어홀의 깊이 및 개수는 지반의 열적 특성에 크게 좌우된다. 열전도율이 큰 지반일수록 지열교환기 내의 열 흡수 및 소산이 효과적으로 이루어져 지열교환기의 길이도 상대적으로 짧아질 수 있다. 즉, 효율적이고 정확한 설계를 하기 위해서는 지반, 암반 및 지중열교환기의 물리적 특성에 따른 열적 특성을 설계자는 미리 숙지하여야 한다. 현재 국내에서 수직 밀폐형 지중열교환기의 그라우트로 벤토나이트를 가장 많이 사용하고 있으나, 해외의 경우 지중 조건에 따라 시멘트 또는 벤토나이트를 적절히 선택하여 시공하고 있다. 이는 벤토나이트의 특성상 적용 조건이 제약을 받기 때문이며, 특히 지하수가 존재하지 않을 경우 사용이 사실상 불가능하다. 국내에서 이에 대한 충분한 연구는 아직 이루어지지 않았으며, 시멘트 그라우트를 사용하기 위한 물리적, 열적 특성에 대한 연구가 필요한 시점이라 판단하여 본 연구를 수행하였다. 시멘트 그라우트의 경우 수화반응이 일어나는 초기의 건조수축을 최소화하는 배합비로 물성을 구성하였으며, 벤토나이트는 일반 현장 시공 비율을 사용하였다. 열전도율은 첫째 실내 시험으로 시멘트 그라우트에 대한 열판시험법과 벤토나이트 그라우트에 대한 탐침시험법으로 수행하여 구하였으며, 두 번째 방법인 현장 시공으로 직접 현장열응답시험을 수행하여 그라우트 간의 열적 특성을 비교하였다. 또한 기존 시멘트그라우트의 열적 특성을 개량한 코오롱건설에서 개발한 시멘트 그라우트에 대한 열적 거동도 기존 타 그라우트의 열적 거동과 비교하였으며, 개발 제품의 성능이 상당히 우수함을 알 수 있었다.

• Tunnel and Underground Space
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• v.32 no.1
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• pp.20-29
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• 2022

The existence of underground cavity should be considered in the assessment of georisk such as ground subsidence. Even if the shear strength of the ground around the cavity is known, it is difficult to accurately analyze the safety around the cavity due to the uncertainties related to geometric conditions such as the cavity size. In this paper, stability chart representing dimensionless stability constants was proposed based on the ground strength and geometric conditions. Numerical analysis had been carried out accounting for the stability constants such as the ground strength, the adhesion and friction angles, and the size and depth of the underground cavity. The proposed charts can help estimating the stability of ground with underground circular cavity.

• Journal of the Korean GEO-environmental Society
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• v.23 no.12
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• pp.55-61
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• 2022

Carbon dioxide is one of the greenhouse gases in the atmosphere and much research is underperforming in reducing carbon dioxide. Geological carbon dioxide storage is considered the primary technique for global warming prevention. So, technic development for storing carbon dioxide is required. Using surfactant is considered an effective material for geological carbon dioxide storage. However, research on using surfactants for carbon dioxide sequestration is not enough. In this study, a 2D micromodel experiment depends on the surfactant type (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate), concentration and carbon dioxide injection rate. As result, geological carbon dioxide sequestration efficiency is increased according to surfactant concentration and carbon dioxide injection rate increase. However, efficiency no more increases after critical concentration and rate.

• Journal of the Korean GEO-environmental Society
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• v.24 no.6
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• pp.5-11
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• 2023

The engineering industry heavily relies on fossil fuels such as coal and petroleum to generate energy through combustion. However, this process emits carbon dioxide into the atmosphere, leading to global warming. To mitigate this issue, researchers have explored various methods to reduce carbon dioxide emissions, one of which is carbon dioxide underground storage technology. This innovative technology involves capturing carbon dioxide from industrial plants and injecting it into the saturated ground layer beneath the earth's surface, storing it securely underground. Despite its potential benefits, carbon dioxide underground storage efficiency needs improvement to optimize storage in a limited space. To address this challenge, our research team has focused on improving storage efficiency by utilizing surfactants. Furthermore, we evaluated how different carbon dioxide states, including gaseous, liquid, and supercritical, impact storage efficiency based on their respective pressures and temperatures within the underground reservoir. Our findings indicate that using surfactants and optimizing the injection rate can effectively enhance storage efficiency across all carbon dioxide states. This research will pave the way for more efficient carbon dioxide underground storage, contributing to mitigating the environmental impact of fossil fuels on the planet.

• Geotechnical Engineering
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• v.13 no.6
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• pp.165-180
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• 1997

The structure such as underground external walls of buildings, conduit and box culvert supports the surcharge loads (point, strip and line loads) . The vertical and horizontal stresses in a soil mass depend on the backfill width and wall friction, etc. The investigations described in this paper is designed to identify the magnitude and the distributions of the lateral and vertical pressure which is occurred by the narrowly backfilled soil in an open cut by the surcharge loads. For these purposes, model tests were performed for various width of backfill in a model test box by considering the wall friction using carbon rods. The results of test were compared with the theories of Weissenbach and VS Army Code and also with the results of the numerical analysis using finite difference method which introduces Mohr-Coulomb failure hypothesis.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.89-96
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• 2008

The study, with regard to unsymmetrically inclined backfilled wall, was intended to estimate the lateral earth pressure, develop the equation for lateral earth pressure and eventually identify the mutual behavior, based on the modified Kellogg theory, while changing the width between the walls, wall angle, relative density and wall friction angle. To verify the geostatic pressure obtained from the study, the results in the wake of 62 kinds of model tests performed were compared and evaluated with the behaviors based on theoretical equations. As a result, the wall inclination angle was found to be the factors affecting the earth pressure the most, when both walls were inclined unsymmetrically. And the narrower the backfill space and the larger the wall inclination angle to the horizontal level, the greater the effect of the wall friction. The equation considering the wall friction reaction indicated the value, which was closer to the actually-measured earth pressure, and when the width between the warts was narrow, the arching effect appeared to be great, thereby indicating the difference between the measured earth pressure, theoretically calculated earth pressure and the geostatic pressure proved to be insignificant.

• Journal of the Speleological Society of Korea
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• no.79
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• pp.65-72
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• 2007

인공토굴(人工土窟) 숙성식품의 장기가공보관 수단의 원조로 자리 잡아, 광천옹암리 토굴이 전통식품 산업의 지혜와 관광산업의 역동으로 변신하고, 인공 굴은 폐광토굴에서 농산물저장을 위한 인공제작 굴의 활용기술로 이어져 산업화사회에 기여하고 있다. 대표적인 인공토굴중의 하나는 광천토굴이며, 마을뒤편 야산에 활석암으로 된 암반을 굴착한 토굴이다. 폭과 높이가 각각 2m 정도, 200여 m의 토굴 속에 수많은 젓갈을 담은 드럼통을 저장하여 숙성, 발효시킨다. 젓갈은 우리나라의 대표적인 수산발효식품이며, 어패류 등에 비교적 다량의 식염을 가해 자가소화효소 및 미생물분해 작용으로 알맞게 숙성되는 원리를 이용한다. 젓갈은 일종의 균 식품으로 식품을 발효시킴으로써 독특한 맛과 향 영양을 갖게 되며, 빵, 요구르트, 장류(간장 된장 등), 김치, 막걸리, 동동주, 식혜뿐 아니라 심지어는 버섯조차도 균 식품에 해당한다. 특히 어패류를 염장 발효시켜서 독특한 감칠맛이 나도록 한 우리나라 특유의 저장식품으로 예로부터 기호식품, 조미료 및 김치의 재료로서 널리 식용되어 왔던 양질의 단백질인 동시에 칼슘과 지방질 공급원이기도 하다. 최근에는 상품화된 자연친화적 농산물저장 굴로 사용되는 인공토굴도 등장하였다. 그것은 타공판과 흙을 이용한 생태환경지중건축물(生態環境地中建築物)로서 우리조상들이 오래전부터 지열을 이용하여 주거와 농산물을 저장하였던 재래식 토굴을 현대화시킨 구조물의 지중저장토굴 공간이다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.823-837
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• 2018

Congestion of the city with the rapid industrial development was accelerated to build complex social infrastructure. And numerous structures have been designed and constructed in accordance with these requirements. Recently, to solve complex urban traffic, many researches of large-diameter tunnel under construction downtown are in progress. The large-diameter tunnel has been developed with a versatile double-deck of deep depth tunnel. For the safe tunnel construction, ground reinforcement methods have been developed in the weakened pillar section like as junction of tunnel. This paper focuses on evaluation of the effects of new developed ground reinforcement methods in double-deck junction. The values of reinforcement determined from the existing and developed methods were compared to each other by numerical simulation.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.3
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• pp.249-256
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• 1988

The purpose of this paper is to research the estimations of the indoor natural temperature in a case of the earth sheltered space and the 1st basement room in comparison with a conventional housing. The result of this study can be summerized as follows: The natural temperature of the earth sheltered house Summer : $${\theta}es=27.0+1.65sin(2{\pi}/24{\cdot}T-1.34)$$ Winter : $${\theta}ew=11.5+1.15sin(2{\pi}/24{\cdot}T-1.61)$$ The natural temperature of the 1st basement space Summer : $${\theta}us=25.5+1.00sin(2{\pi}/24{\cdot}T-1.72)$$ Winter : $${\theta}uw=13.9+1.10sin(2{\pi}/24{\cdot}T-2.29)$$ From the results of the stated above, we can calculate the cooling and heating load in the earth sheltered house and the underground space exactly and easily at Taejeon City.