• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2001.03a
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• pp.109-117
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• 2001

불연속체 해석을 이용하여 터널 안정성 해석을 수행할 경우 해석 결과는 절리 모델의 선택에 따라 달라진다. 따라서 본 연구에서는 개별요소법을 이용한 불연속체 터널 안정성 해석에 있어 BB 모델 적용시의 해석 결과와 MC 모델 적용시의 해석 결과를 비교하였다. 또한 주어진 응력 조건과 터널 형상에 따른 암반의 변형 거동을 규명하기 위하여 불연속체 해석 결과와 연속체 해석 결과를 비교하였다. 연속체 해석결과와 BB 모델을 사용한 불연속체 해석 결과는 변위 및 응력 분포는 비슷한 양상을 보이는 반면, MC 모델을 사용한 불연속체 해석결과는 이와 다른 양상을 보였다. 또한 MC 모델을 사용하여 불연속체 해석을 실시할 경우 절리의 영향을 명시적으로 고려하였음에도 불구하고 연속체 해석 결과에 비해 변위 및 최소 주응력이 더 작게 발생할 수 있음을 확인할 수 있었다. 이는 MC 모델이 실제 절리의 변형거동 특성을 현실적으로 모사할 수 없기 때문에 발생되는 결과이며, 특히 절리면의 전단거동에 무관하게 팽창각을 일정한 상수로 취급하는 MC 모델의 특성으로 인한 결과이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.307.1-307.1
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• 2013

고진공 상태의 희박한 농도를 가진 분자들은 불연속체의 특징을 가지게 되며, 일반적인 연속체 시뮬레이션으로 물리적 현상을 예측할 수 없었다. 이에 불연속체 시뮬레이션이 가능하도록 분자동역학을 기반으로 한 해석기술을 구축하기 위한 연구를 진행하였다. 아울러 태양전지 고진공 증발증착 공정의 실험결과와 비교하여 시뮬레이션의 적합성을 확인하고 변수의 영향도를 검토하였다. 향후 다양한 변수에 따른 시뮬레이션이 진행되어야 하며, 불연속체와 관련된 솔루션을 제공할 수 있는 데이터와 노하우의 축적 및 해석기술 표준화가 진행되어야 한다.

• Tunnel and Underground Space
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• v.31 no.5
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• pp.309-332
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• 2021

Natural barrier systems surrounding the geological repository for the high-level radioactive waste should guarantee the hydraulic performance for preventing or delaying the leakage of radionuclide. In the case of the behavior of a crystalline rock, the hydraulic performance tends to be decided by the existence of discontinuities, so the coupled hydro-mechanical(HM) processes on the discontinuities should be characterized. The discontinuum modelling can describe the complicated behavior of discontinuities including creation, propagation, deformation and slip, so it is appropriate to model the behavior of a crystalline rock. This paper investigated the coupled HM processes in discontinuum modelling such as UDEC, 3DEC, PFC, DDA, FRACOD and TOUGH-UDEC. Block-based discontinuum methods tend to describe the HM processes based on the fluid flow through the discontinuities, and some methods are combined with another numerical tool specialized in hydraulic analysis. Particle-based discontinuum modelling describes the overall HM processes based on the fluid flow among the particles. The discontinuum methods that are currently available have limitations: exclusive simulations for two-dimension, low hydraulic simulation efficiency, fracture-dominated fluid flow and simplified hydraulic analysis, so it could be improper to the modelling the geological repository. Based on the concepts of various discontinuum modelling compiled in this paper, the advanced numerical tools for describing the accurate coupled HM processes of the deep geological repository should be developed.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.167-173
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• 2001

The joint model has influence on the results of discontinuum analysis. In this study the results of discontinuum analysis with Barton-Bandis joint model(BB model) and with Mohr-Coulomb joint model(MC model) are compared. The results of continuum analysis under the same condition are compared with the results of discontinuum analysis to investigate the behavior of rockmass around tunnel. The result of continuum analysis and that of discontinuum analysis with BB model show similar distribution of displacement and stress. On the other hand, the discontinuum analysis with MC model shows different displacement distribution and stress distribution. Moreover, the displacement and minor principal stress of the discontinuum analysis with MC model are smaller than those of continuum analysis, although the joints are explicitly considered in the discontinuum analysis. These results are originated from the limitation of MC model in simulating joint deformation behavior, especially the assumption of constant dilation jingle independent of it)int 7hear displacement.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.394-404
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• 2006

Dynamic behavior of rock structures depends largely on the dynamic characteristics of ground and input earthquake wave. For blocky rocks with intense discontinuities, the mechanical characteristics of blocks and structural and mechanical characteristics of discontinuities affect overall behavior. In this study, UDEC was adopted to evaluate the dynamic behavior of rocks with various structural characteristics. Obtained results were compared to those of $FLAC^{2D}$, a continuum analysis, and the validity of the method was examined for dynamic analysis of discontinuous rocks for earthquake. Analysis considering the discontinuity showed significant changes in structural shape by the influence of joint behavior, and the behavior by continuum analysis was overestimated.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2001.03a
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• pp.97-108
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• 2001

절리가 발달한 암반의 거동평가를 위한 해석적 방법은 연속체 모델과 불연속체 모델을 사용하는 방법으로 대별할 수 있으며, 연속체 모델을 사용할 경우에는 유한요소법이나 유한차분법을 이용하는 방법이 주종을 이루고 있다. 불연속체 모델은 개별 블록들의 움직임을 일일이 계산하므로 매우 매력적인 방법이지만 현재의 지반조사 기술수준으로는 지반내의 절리발달사항을 정확히 파악하기가 매우 어려우며, 컴퓨터의 계산용량이 너무 과다해지는 단점이 있다. 따라서, 불연속면을 포함한 암반을 연속체로 가정한 편재절리 모델(ubiquitous joint model)을 이용한 연구가 요구된다. 한편, 터널의 경우는 사면의 경우와는 달리 파괴면의 형상을 사전에 가정하기 어렵기 때문에 한계평형법에 기초한 해석법 등을 적용하여 안전율을 구하기가 곤란하다. 이러한 이유에서 터널을 대상으로 한 수치해석은 안전율을 구하기보다는 안정성을 평가하는 데만 제한적으로 사용되어 왔다. 본 논문에서는 편재절리모델을 이용한 절리암반터널의 거동 평가기법과 수치해석에 의해 터널의 안전율을 구하는 방법을 제시하는 데에 그 목적이 있다. 이를 위해 터널의 안전율 구하는 방법을 강도감소기법에 근거하여 제시하였다.

• The Journal of Engineering Geology
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• v.5 no.2
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• pp.155-165
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• 1995

Fluid flow studies of fractured rocks require three-dimensional modeling of the fracture system. The stochastic discrete fracture models constructed by Monte Carlo simulation technique were applied to the analysis of groundwater flow and mass transport in fractured rock for the assessment of tightness criteria of underground LPG storage cavern. The parameters that most affect the conceptual discrete fracture modeling proved either fracture orientation or size and on the fract'lre flow interpretation proved conductive fracture intensity. The fracture transmissivity played important role in solute transport in fractured rock simulated by particle tracking approach. It was partly recognized that the calibrated stochastic discrete fracture model can be used for the tightness criteria of underground LPG storage cavern.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.377-389
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• 2008

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.163-170
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• 2000

The distinct element method has been effectively applied to the analysis of stability and behavior of jointed rock masses. In this paper the modelling characteristics of different types of distinct element model were investigated. Arch tunnel examples were chosen to compare the calculation results of two computer codes, NURBM and CBLOCK, where the former is based on implicit algorithm, and the other on explicit one. CBLOCK calculations show that joint properties are very important parameters in the stability analysis and that the joint stiffness ratio associated with joint configuration could be used as an indicator, whereas NURBM differ from that. Some other disagreements were also identified.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.410-417
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• 2000

The distinct element method has been effectively applied to the analysis of stability and behavior of jointed rock masses. In this paper the modelling characteristics of different types of distinct element model were investigated. Arch tunnel examples were chosen to compare the calculation results of two computer codes, NURBM and CBLOCK, where the former is based on implicit algorithm, and the other on explicit one. CBLOCK calculations show that joint properties are very important parameters in the stability analysis and that the joint stiffness ratio associated with joint configuration could be used as an indicator, whereas NURBM differ from that. Some other disagreements were also identified.