• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.10a
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• pp.137-146
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• 2007

해저 지하 구조물을 시공할 경우는 높은 수압 및 침투압 등의 영향이 무시될 수 없으므로 지하저장 공동의 정확한 거동평가를 위해서는 수리-역학적 해석이 수행되어야만 한다. 또한, 실무에서는 암반이완하중을 고려하여 터널의 콘크리트 라이닝을 설계하며, 이를 위해 이완하중고를 터널 주변의 국부안전율 분포를 이용하여 수치해석에 의해 산정하는 방법이 제안된바 있다. 따라서 본 연구에서는 해저터널을 대상으로 수리-역학적 연계해석 시 국부안전율을 이용한 이완하중고 산정 기법의 타당성을 살펴보았다. 이를 위해 3등급 암반을 대상으로 숏크리트 수리특성을 이용한 유도배수방법과 집수정의 펌핑을 이용한 유도배수방법을 이용하여 이완하중고를 산정하고 적용성을 비교하였다. 연구 결과 연계해석 시 해저시설물의 안전율 및 이완하중고를 정확하게 산정하기 위해서는 집수정의 펌핑을 이용하여 유도배수하는 모델링 방법이 보다 정확하고 일관성 있는 결과를 얻을 수 있었다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.141-150
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• 2009

When constructing a subsea tunnel in discontinuous rock mass, fluid flow in joints has a great influence on the behavior of the tunnel so that hydro-mechanical coupled analysis should be performed for the stability estimation. In practice, relaxed rock load is generally used for the design of tunnel concrete lining. In a continuum analysis, a method based on the distribution of local safety factor around a tunnel was proposed for the estimation of a potential relaxed zone. However, in the case of discontinuous rock mass in which joints are developed, the whole stability of tunnels depends on the behavior of the joints. In this study, therefore, a method is proposed for the estimation of a potential relaxed zone occurred by the excavation of a tunnel in discontinuous rock mass. The suggested method is validated by sensitivity analysis and the comparison with the results of continuum analysis.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.13-21
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• 2014

This study analyzed the differences in the analysis techniques through a comparative analysis of the various segment's modeling techniques of Shield TBM method and proposed reasonable modeling techniques. Also, this study suggested reasonable estimating methods of load to be applicable in the field through the load analysis and three-dimensional finite element analysis by estimating model of rock mass relaxation load. Estimating method of relaxation area by rock mass rating makes no odds of output in subgrade with high rock mass rating, but so the difference of output is large, that is judged to set conservative design off. In estimating result of rock mass relaxation area by three-dimensional analysis relaxation area of subgrade with low-grade soil was predicted to be positioned at medium-range of many methods, in case of designing segment in subgrade with low-grade soil it needs to actively review estimation of relaxation area through three-dimensional analysis reflecting mechanical tunnel excavation.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.96-108
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• 2001

A concrete lining of NATM tunnel is the final product of a process that involves planning and evaluation of user needs, geotechnical investigations, analysis of ground-lining interaction, construction, and observations and modifications during construction. The designer must consider the lining in context of the many function, construction, and geotechnical requirements. Also, the loss of supporting capacity of shotcrete lining due to poor rock qualities and shotcrete erosion must be considered. The values, shapes, and estimating methods of rock load and water pressure are very different with every designers. Estimating methods of rock loads used in the design of NATM tunnel concrete lining are investigated. Structural analyses are done in various load combinations, and the member forces(moment, axial force and shear force) are compared. The adequate load combination of rock load and water pressure is proposed.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.570-580
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• 2005

NATM 터널에 작용하는 토압(이완하중)의 크기는 지형조건, 지질조건등에 따라 다르므로 정량적으로 산정하기에는 다소 어려움이 있으며, 실무적으로 Terzaghi(1946)가 제안한 암반의 이완하중을 적용하고 있다. Terzaghi 암반이완하중은 지형상 저토피, 편경사등을 고려하기에는 다소 무리가 있고 특히, 설계시 시공중 공용후 터널에 편토압이 작용한다고 예측하는 것은 더욱 어렵다고 할 수 있다. 본 연구에서는 저토피 편경사지형에서 터널의 문제점 보강대책방안에 대하여 종합 검토하였으며, 실제 지형상 저토피, 편경사를 이루나 암질이 양호하다고 판단되어 아칭 효과를 기대할 수 있을 것으로 예상되는 터널이 굴착과정중 설계시 추정된 지반조건과 상이하여 터널지보재(숏크리트)의 균열 및 이상 변위가 발생된 터널에서 보강대책방안으로 인버트폐합을 실시하여 안정된 터널굴착을 할 수 있었던 사례를 소개하고 저토피 편경사 지형에서 NATM 터널의 설계 시공시 유의사항에 대하여 검토하였다.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1995.03a
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• pp.181-185
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• 1995

현재 구미에서 터널의 설계에는 RMR, Q와 같은 암반분류 기법과 경계요소 해석법과 같은 간략한 탄성 프로그램에 경험적 파괴조건식을 적용하여 이완대를 계산하고 터널의 지보량을 추정하는 방식이 널리 적용되고 있다. RMR이나 Q와 같은 암반분류법은 지하공동의 안정성에 영향을 미치는 중요한 지질 요인들에 근거하여 암반을 몇가지 등급으로 분류하고 지보방법을 결정하는 분류 방식으로 가장 많이 사용되고 있으나 각 항목의 평가방식이 경험적인 판단을 요하게 되어 주관적인 오류에 빠질 가능성이 많고, 또 여러 가지 대체 수단이 있어 종합적인 판단을 얻기가 용이하지가 않다. (중략)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5C
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• pp.359-368
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• 2006

After construction, time-variant seepage and long-term underground motion are representative factors to understand the abnormal behavior of tunnels. In this study, numerical models have been developed to analyze the behavior of tunnels associated with seepage and long-term underground motion. Possible scenarios have been investigated to establish causes-and-results mechanisms. Various parameters such as permeability of tunnel filter, seepage condition, water table, long-term rock mass load, size of damaged zone due to excessive blasting have been investigated. These are divided into two sub-parts depending on the tunnel type and major loading mechanisms depending on the types. For the soft ground tunnels, the behavior associated with seepage conditions has been studied and the effect of permeability change in tunnel-filter and the effect of water-table change which are seldom measurable are investigated in detail. For the rock mass tunnels, tunnel behavior associated with the visco-plastic behavior of rock mass has been studied and the long-term rock mass loads as a result of relaxation and creep have been considered.

• Journal of Korean Society of societal Security
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• v.2 no.2
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• pp.75-83
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• 2009

When the exposed surface of rock slopes investigated, various factors have not been considered. The factors required to be considered include the vlume swelling of rock caused by stress release at the fault zone, unexposed discontinuities in the earth and so on. Also, rock slope failure occurs sometimes due to these factors. In this paper, we intend to help engineers to judge about the stability of similar new cutting-slopes or the maintenance of already cut-slope, so that they can consider these factors.

• Explosives and Blasting
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• v.42 no.3
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• pp.49-57
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• 2024

Pre-fracturing is the blasting method to weaken the rock mass prior to the main excavation. This study aims to evaluate the effectiveness of pre-fracturing by using half the explosive charge typically employed in conventional blasting designs. Field tests conducted at a quarry in Gapyeong showed that noise levels were reduced by 2.7 dB due to the decreased amount of explosive per blast hole, and vibration levels were controlled to the precision vibration control blasting standard. Rock weakening was confirmed through induced cracks observed on the surface and core samples, and it was noted that the weakening effect of the blasting decreased as the burden increased. The vibrations from conventional blasting were found to be lower than those from pre-fracturing. This was attributed more to the geological conditions, such as joints, rather than the blasting design factors like explosive amount, burden, and the number of free face.

• 지반과기술
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• v.3 no.2
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• pp.19-27
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• 2006