• The Journal of Engineering Geology
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• v.8 no.3
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• pp.225-234
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• 1998

The behavior of the underground opening depends mainly on the magnitude of the initial stress existing before excavation and on the stress redistribution due to the excavation. In the case of elasto-plastic materials such as rock mass, as the structural behavior of surrounded opening due to excavation depends on the stress path, methods and sequence of excavation have influences on the results of numerical analysis. Therefore, in order to design underground openings with large cross-section such as underground nuclear power plants, radioactive waste disposal cavems, oil storage caverns, and so on more reasonably it is desirable to consider the effect of the excavation sequence in the analysis. In this paper, the underground structure is analyzed using the finite element method and the distinct element methods with a view to review the the effect of the excavation sequence. Based on the results of the analysis the followings are discussed : influence of excavation shape and sequence, effect of structural reinforcements, influence of multi caverns.

• New & Renewable Energy
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• v.3 no.4
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• pp.16-21
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• 2007

국토가 좁고 천연자원이 부족한 우리나라에서 전기생산의 대부분을 원자력 발전에 의존하고, 화력발전을 많이 활용하는 것은 당연한 일이다. 그러나, 각종 신기술의 개발과 함께 신에너지원에 대한 가능성이 증대되고 있어 이에 대한 연구와 투자도 소홀히 할 수 없는 상황에 있다. 신에너지원으로 거론되는 여러 가지 대안 가운데 비교적 국내기술로 접근하기 쉬운 부분이 지열을 활용한 분야이다. 일본, 필리핀, 인도네시아와 같은 화산국은 물론이고 우리나라와 같이 활화산이 없는 나라에서도 대심도에서는 지열자원이 고르게 분포해해 있을 것으로 추정되어 개발된 지열활용기술은 그 수요처가 상당히 젊다고 할 수 있다. 본 연구에서는 지열활용을 위하여 필수적으로 사용되는 지열정 굴착기법과 건설에 따라 우려되는 환경영향을 정리하였다. 지열활용에 사용되는 지열정의 종류를 파악하고, 그에 따른 굴착기술을 소개하였으며, 저비용 고효율 굴착을 위한 요소기술들을 정리하였다. 그리고, 국외의 자료를 통하여 지열발전 프로젝트에서 우려되는 환경영향을 조사하여 국내의 상황과 비교하여 고찰하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.533-537
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• 2007

국토가 좁고 천연자원이 부족한 우라나라에서 전기생산의 대부분을 원자력 발전에 의존하고, 화력발전을 많이 활용하는 것은 당연한 일이다. 그러나, 각종 신기술의 개발과 함께 신에너지원에 대한 가능성이 증대되고 있어 이에 대한 연구와 투자도 소홀히 할 수 없는 상황에 있다. 신에너지원으로 거론되는 여러 가지 대안 가운데 비교적 국내기술로 접근하기 쉬운 부분이 지열을 활용한 분야이다. 일본, 필리핀, 인도네시아와 같은 화산국은 물론이고 우리나라와 같이 활화산이 없는 나라에서도 대심도에서는 지열자원이 고르게 분포해 있을 것으로 추정되어 개발된 지열활용기술은 그 수요처가 상당히 넓다고 할 수 있다. 본 연구에서는 지열활용을 위하여 필수적으로 사용되는 지열정 굴착기법과 건설에 따라 우려되는 환경영향을 정리하였다. 지열활용에 사용되는 지열정의 종류를 파악하고, 그에 따른 굴착기술을 소개하였으며, 저비용 고효율 굴착을 위한 요소기술들을 정리하였다. 그리고, 국외의 자료를 통하여 지열발전 프로젝트에서 우려되는 환경영향을 조사하여 국내의 상황과 비교하여 고찰하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.640-655
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structures. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process in the ground under the excavation basement can affect the existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effect of the excavation of the ground and the new structure load on the existing tunnel was experimentally implemented and the influence of the adjacent construction on the existing tunnel was investigated. For this purpose a large testing model with 1/5 scale of the actual size was manufactured. The influence of ground excavation, width of the load due to new structure, and distance between centers of tunnel and of excavation on the existing tunnel was investigated. In this study, it was confirmed that the influence on the existing tunnel gets larger, as the excavation depth get deeper. At the same distance, it was confirmed that the tunnel displacement increased up to three times according to the increase of the building load width. That is, the load width influences the existing tunnel larger than the excavation depth. As the impact of the distance between centers of tunnel and of excavation, it was confirmed that tunnel crown displacement decreased by 48%. The result showed that a tunnel is located in the range of 1D (D: tunnel diameter) from the center of excavation, the effect of excavation is the largest.

• Journal of the Korean GEO-environmental Society
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• v.5 no.4
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• pp.81-91
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• 2004

In present study, the effect of tunnel excavation on groundwater was investigated by a case study and numerical analysis. The case study revealed that groundwater can be one of environmental impacts resulting from tunnel excavation. To examine variations in groundwater level due to tunnel excavation, numerical analysis was performed. The analysis result indicated that tunnel excavation could affect the groundwater behavior as the groundwater adjacent to tunnel flows in it. Also, it was found that, for the case where groundwater flowing though fractured zone passes tunnel exacvation area, a special care with the excavation would be needed to avoid any tunnel instability due to a large qunatity of goundwater flowing in it.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.669-676
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• 2023

This study analyzed the relationship between major parameters and numerical analysis results according to various excavations conducted around the urban railway, application of machine learning techniques and verified the scope of influence of the adjacent excavation on the existing urban railway box structure and the appropriateness of the safety area. This study targeted the actual negotiated adjacent excavation works and box structures around the urban railway, and the analysis was conducted on the most representative two-line box structures. The analysis confirmed that the difference in depth of urban railway, excavation depth of adjacent excavation, and depth of underground water level are important parameters, and the difference in excavation depth of adjacent excavation is the parameter that affects the behavior of underground box structures and is an important requirement for setting safety areas. In particular, the deeper the depth of the adjacent excavation work, the greater the effect on the deflection of the underground box structure, and the horizontal separation distance, one of the important requirements for determining the management grade of the existing adjacent excavation work, is relatively small.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.421-435
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• 2012

Rock excavation (removal) tests are performed with effective parameters using an abrasive waterjet. For verification of the field rock excavation capabilities, the removal performance and level of efficiency are analyzed for hard granite rock in terms of the water pressure, exposure time of the jet, and the standoff distance. In particular, experimental tests are performed with a long standoff distance required condition in the real excavation field. The rock removal performance level changes according to the rock properties. In this study, various rock specimens are used and P-wave velocities are measured in order to determine the correlation between the removal performance and the P-wave velocity. As a result of the experimental study, the effect of waterjet parameters on rock removal is analyzed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.435-450
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• 2020

The divergence section of a double-deck tunnel can be divided into a 'widening pre-divergence section', a large cross-section with a cap shape and a 'post-divergence section' where the separation between the main and the branch tunnel is made. Since the cross-section of the widening pre-divergence section is considerably larger than that of the post-divergence section, the influence of excavation due to the different sizes and shapes in the cross-section should be considered in the examination of the tunnel stability. In this study, the effect of the preceding excavation, that is the excavation of the widening pre-divergence section, on excavation stability of the post-divergence section was examined by varying the excavation methods and bench lengths through 3D finite element analysis. The results showed that although the effects of the excavation methods and the bench lengths are not significant on the variation of principal stresses, the preceding excavation causes a relatively large variation on the stresses which may have an impact on the stability of the post-divergence section from the comparison of Stress-Strength Ratio (SSR) between the cases with and without the consideration of the preceding excavation effect by 2D finite element analysis.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.27-36
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• 2008

This paper analyzed the effects related to the difference of the geometrical shape of the ground excavation by comparing the displacements of the earth retaining wall of the strut resulting from the change of the excavation breadth B and the excavation length L, adopting the three dimensional FDM analysis. It appeared that the displacement of the earth retaining wall of the strut increases in accordance with the increase of L/B and it decreases as it becomes nearer from the center to the comer where the temporary structural system forms, and the wale member is closured because of the effects of the confining effect by the closure of the earth retaining wall and the wale member. This paper proposed a formula in which the results of three dimensional FDM analysis which considers the shape of the excavation plane can be obtained from those of two dimentional FDM analysis which does not consider the shape of the excavation plane. And the results of the formula were compared with those of the site instrumentation analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.731-742
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structure. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process is repeated in the lower ground of the excavation so that it can affect existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effects of the ground excavation and the new structure load on the existing tunnel were investigated by large - scale experiment and numerical analysis. For this purpose, a large model tester with a size reduced to 1/5 of the actual size was constructed, and model tests and numerical analyzes were carried out to investigate the effects of the excavation of the body ground by maintaining the distance between the excavation floor and the tunnel ceiling constant, The impacts were identified. As a result of the study, it was confirmed that the deeper the excavation depth, the larger the influence on the existing tunnel. At the same distance, it was confirmed that the tunnel displacement increased with the increase of the building load, and the ground stress increased up to 2.4 times. From this result, it was confirmed that the effect of the increase of the underground stress on the existing tunnel is affected by the increase of the building load, and the influence of the underground stress is decreased from the new load width above 3.0D.