• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.229-238
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• 2002

This paper introduces the surface roughness parameter, Rs to the characterization of joint roughness and quantitatively illustrates the influence of joint roughness on the joint shear strength. A new peak shear strength criterion for rock joints using Rs is suggested. The results show that the surface roughness parameter, Rs can appropriately reflect the degree of roughness for the rock joint surfaces tested in this study A measuring interval of 2mm and profile length of 5cm can be used to characterize the joint roughness of the rock core size surfaces; however, the scale of fluctuation, $\delta_\alpha$ should be considered to extend the surface roughness parameter, Rs to the large-scale field rock joint surfaces. For the smooth joint roughness, sliding of the rock cores is the principal shear mechanism; however, the breakage of roughness from the rock cores is inferred for rougher joint roughness.

• Tunnel and Underground Space
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• v.19 no.1
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• pp.1-10
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• 2009

Site characterization for structural stability in rock masses mainly involves the collection of joint property data, and in the current practice, much of this data is collected by hand directly at exposed slopes and outcrops. There are many issues with the collection of this data in the field, including issues of safety, slope access, field time, lack of data quantity, reusability of data and human bias. It is shown that information on joint orientation, spacing and roughness in rock masses, can be automatically extracted from LIDAR (light detection and ranging) point floods using the currently available Split-FX point cloud processing software, thereby reducing processing time, safety and human bias issues.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.494-507
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• 2011

Rock joint surface roughness is one of the most important parameters in shear behavior analysis of rock joint surface. Until now, estimation of joint surface roughness has been conducted by various statistical methods with two-dimensional analysis. In this study, standard roughness profile suggested by Barton and Choubey (1977) was expanded into a 3D surface and its surface roughness was analyzed by surface angularity parameter. And the validity of quantification based on surface angularity was secured through comparison with $Z_2$ and Ai parameter. Also the surface angularity parameter was compared with shear strength by joint shear test using the replicated specimen.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1999.03a
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• pp.17-23
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• 1999

본 논문에서는 절리면 거칠기를 정밀하게 수치화 하기 위해 레이저 변위계를 이용한 3차원 거칠기 측정기를 구동시키는 프로그램 제작 및 여러 가지 상태의 절리면에 대해 수치화를 실시하여 각종 거칠기 파라미터를 결정한 후 오차분석을 실시하여 이 기계를 이용한 측정의 타당성을 검증하였다. 동일한 절리면에 대해 물리적인 접촉에 의한 3차원 거칠기 측정기로부터 얻어진 거칠기 파라미터와 레이저 변위계를 이용한 측정기로부터 얻어진 것들 사이의 관계를 살펴보았고, 레이저 측정기에 의해 수치화된 절리면 거칠기 파라미터 사이의 상관관계를 조사하였다. 연구에 사용한 시료는 황등화강암, 여산대리석의 2종류이며, 절리형상 측정을 위한 절리는 인장균열 발생장치를 이용하여 인공적으로 제작하였다. (중략)

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.5-11
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• 2010

If the groundwater in rock joint is changed into ice, it induces the stress increment by volume increase. Also, if the ice is changed into groundwater again, the stress in joint decreases by volume decrease. The accumulated displacement and fatigues of joints are increased by the stress-hysterisis, induced from the continuous frost-thawing. Also the shear strength is decreased by them continuously. The stress-hysterisis is affected by the atmospheric temperature changes, whose behavior is visco-elasticity, usually. Therefore, Kelvin model could be used to analyze the frost-thawing behavior in winter. The measured data of total 5 points are examined, which are composed of 3 points of shallow joints and 2 points of deep joints. Because shallow weathered rocks have many joints, a lot of Kelvin model are connected and the behaviors are complicated. In case of deep joints, simple Kelvin model is applied and the behaviors are also simple.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.384-395
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• 2016

Both the roughness measurement tests and the multi-stage shear tests were carried out on the 110 rock joint samples in order to investigate the influences of rock type, joint roughness and normal stress on the shear behaviour of rock joints. Test samples were composed of quartz porphyry, dacite, granite and gneiss, which were classified into three detailed groups according to their JRC values. Roughness parameters of rock joints were analyzed by roughness measurement tests, and shear characteristics were also investigated by multi-stage shear tests. Both peak shear strength and shear stiffness were increased as both joint roughness and normal stress were increased, whereas dilation angles showed lower values at the lower roughness and higher normal stress conditions. Besides, shear characteristics obtained from all tests of four different rock types with different rock strengths showed irrelevant details, therefore the influences of both joint roughness and normal stress on shear behaviors were found to be more considerable than the strength of intact rock. The results obtained from both multi-stage shear tests and direct shear tests were finally compared, where the dilation angles obtained from multi-stage shear tests were found to be valid only for the first normal stress conditions.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.301-315
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• 2001

본 연구에서는 최근 5년간 국내 각 지역에서 채취한 802개의 절리면 시료에 대하여 전단시험을 실시하여 얻은 결과를 이용하여, 절리면의 여러 공학적 성질들을 조사, 연구하였다. 절리면 전단시험에서 얻어진 최대마찰각 및 잔류마찰각을 지체구조별, 암종별로 분류하고 통계적으로 구하였으며, Barton의 전단강도식의 입력변수인 JRC, JCS를 측정하고 Barton식의 적용성에 대해서도 검토하였다. 그 결과 설계의 기초자료로 활용할 수 있는 지역별, 주요 암종별 최대마찰각, 잔류마찰각을 제시하였다. 또한, JRC, JCS, 수직응력에 따른 마찰각과 전단강성 및 팽창각의 변화를 분석하였다. 마지막으로, Barton의 식에서 구한 이론적 전단강도와 이 실험에서 얻어진 전단강도를 비교한 결과, Barton의 경험식은 높은 상관도로 암석 절리면 전단강도를 예측할 수 있음을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.17 no.1
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• pp.85-97
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• 2001

Tse와 Cruden(1979)에 의해 암석 절리면 거칠기 정량화에 대한 연구가 시작된 이후 통계적인 정량화방법, 프랙탈 차원을 이용하는 방법 그리고 스펙트럼 분석을 이용하는 방법이 제안되었다. 이러한 통계적 정량화방법은 치수의존적이라는 단점이 있으며, 프랙탈 차원을 이용하는 방법은 크로스오버 차원이라는 문제점이 있는 것으로 평가되고 있다. 이 문제점들을 보완하는 방법으로 스펙트럼 분석법이 제시되어 많은 연구가 이루어졌다. 본 연구에서는 Barton과 Choubey(1977)가 제안한 10개의 절리면 프로파일을 수치화하고 통계적 분석, 프랙탈 차원 분석 그리고 스펙트럼 분석을 실시하여 이들 문제점을 살펴보고 스펙트럼 분석법이 위상이 변조된 프로파일에 대하여 문제가 있음을 확인하였다. 이들 문제점을 해결하기 위하여 측정간격과 프로파일의 기울기를 의미하는 통계적 파라미터의 관계를 선형으로 회귀분석하였다. 이렇게 구한 10개의 1차식의 기울기와 절편은 JRC와 매우 상관성이 높게 나타났다. 이 기울기와 절편을 거칠기 정량화의 변수로 사용함으로서 통계적 분석법에서의 치수의존적인 문제와 스펙트럼 분석에서의 위상변조의 문제를 해결하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.3
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• pp.15-29
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• 2001

For the pertinent use of NMT method, both characteristics of joints (JRC, JCS and ${\phi}_r$) and characteristics of rock mass (Q-Value) must be investigated carefully. The main objective of the study presented is to investigate how sensitive the predicted behaviour of an underground excavation is to various realistic assumptions about some input parameter for the jointed rock mass. Joint pattern in the tunnel is predicted by statistical approach (chi-square test). In this paper, sensitivity studies involving in joint characteristics were carried out. The parametric studies involving change in Barton-Bandis joint model have shown that JCS is relatively insensitive to JRC and ${\phi}_r$. An increase in JRC value may not, according to the Barton-Bandis model, necessarily lead to a decrease in displacement. The importance of dilation in predicting the behaviour of a rock mass around an excavation is emphasized from a comparison of the Barton-Bandis joint behaviour model with the Mohr-Coulomb model. The Barton-Bandis model predicted higher stress, which allow for the build-up of stress caused by dilatant behaviour.

• Tunnel and Underground Space
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• v.12 no.4
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• pp.312-320
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• 2002

It is well-known that when single rock fractures undergo shear displacement, they are influenced by the boundary conditions and fracture roughness. In this case, aperture geometry will change by means of dilation due to the shear displacement. As fractures become the flow paths, fluid flow through rock fractures is affected by the void geometry. In this study, therefore, the influence of roughness on shear behavior of fractures has been investigated, and the resulting hydraulic behavior has been analyzed. In order for this study, a statistical method has been used to generate rough fractures, and they have been adopted into new conceptual models fur fracture shearing and flow calculations. The main contributions of this study are as follows: firstly, fracture shear behavior becomes less brittle with decreasing fracture roughness and increasing normal stress. Then, the characteristics of aperture distribution becomes those of roughness of fractures indicating its hydraulic significance. Finally, it is observed that with decreasing fracture roughness the breakdown of channel flow occurs more slowly.