• Proceedings of the KSEG Conference
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• 2000.04a
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• pp.165-173
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• 2000

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.321-334
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• 2003

This study is aimed at the effective measurement plan of discontinuity orientation on rock mass. The discontinuity orientation is expressed as three methods. strike/dip. dipdirection/dip (a three digit number / a two digit number) and right hand rule. Generally, strike/dip is measured with clinometer. and dipdirection/dip with silva compass(type15). A sign of strike/dip. discontinuity orientation is used to geological survey. and dipdirection/dip to engineering. Dipdirection/dip converted by strike/dip measured with clinometer is useful on the statistical analysis of a lot of data. To measure the azimuth of the dip with clinometer and to change strike/dip to dipdirection/dip may have potential errors in each person. The newly designed apparatus, clinometer equipped by a rotational azimuth plate and an arrow to measuring strike and dipdirection, has been developed to measure effectively the discontinuity orientation with two method (strike/dip and dipdirection/dip). The measuring method of discontinuity orientation with clinometer having newly designed apparatus is effective one for accurate measurement of strike as well as dipdirection which is degrees counted clockwise from true north. Used by clinometer with newly designed apparatus, concurrent measuring strike/dip and dipdirecton/dip of discontinuity is possible. In application to measuring discontinuity orientation on rock slope, it has been recognized that the newly designed method, unambiguously, led to drop measuring errors comparing with existing measuring apparatuses. Therefore, it is considered that measuring method of discontinuity orientation (strike/dip and dipdirecton/dip) by the newly designed apparatus is useful to one in geological engineering investigation of road design, and to unskilled investigator.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2002.03a
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• pp.75-86
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• 2002

• Tunnel and Underground Space
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• v.29 no.5
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• pp.318-331
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• 2019

A three-dimensional(3D) equivalent continuum modeling was performed to analyze hydraulic behavior of rock mass considering discontinuities by using DFN model and smeared fracture model. DFN model was generated by FLAC3D and smeared fracture model was applied by using FISH functions, which is built-in functions in FLAC3D, for equivalent continuum model of fractured rock mass. Comparative analysis with 3DEC, which is for discontinuum analysis, was conducted to verify reliability of equivalent continuum analysis by using FLAC3D. Similar results of hydraulic analysis under the same conditions could be achieved. Equivalent continuum analysis of fractured rock mass by using DFN model was implemented to compare with existing analytical methods for inflow into the tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.265-274
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• 2010

In many tunnels, falling or sliding of rock blocks often occur, which cannot be predicted because of the complexity of rock discontinuities and it has brought an exponential increase in costs and time to manage. It is difficult to estimate the properties of rock masses before the tunnel excavation. The observational design and construction method in tunnels has been becoming important recently. In this study, a new hybrid stochastic-deterministic rock block analysis method for the prediction of the unstable rock blocks before the tunnel excavation is proposed, and then applied to the tunnel construction based on actual rock discontinuity information observed in the field. The comparisons and investigations with the analytical results in the tunnel construction have confirmed the validity and applicability of this new hybrid stochastic-deterministic rock block analysis method in tunnels.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.548-556
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• 2009

In order to evaluate applicability of rock cut-slope investigation system, typical clinometer and photogrammetry investigation system were used for rock slopes; first for 7 discontinuities, and secondly, 10 discontinuities, and the results were compared. The first verification was performed depending on discontinuity joint shapes and slope angles, and the second verification was performed depending on shot time and shot locations. The results showed that differences of dip direction $1^{\circ}{\sim}4^{\circ}$, dip $0^{\circ}{\sim}4^{\circ}$. In the second verification test, the differences of dip direction was $0^{\circ}{\sim}6^{\circ}$, and dip $0^{\circ}{\sim}6^{\circ}$. The photogrammetry method for rock slope survey system is quite reliable when clinometer generally shows ${\pm}10^{\circ}$ errors due to surface roughness and investigator.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.123-131
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• 2009

Large scale model tests and numerical analyses were performed in order to investigate the stress distribution on the base of pillar during two-arch tunnel excavation in the regularly jointed rocks. It was observed that the stress was irregularly distributed on pillar and the angle of discontinuities seriously influenced on the stress distribution on the pillar base in the discontinuous rock mass. In the numerical analyses results, It was shown that the stress level of pillar was greatly changed depending on the excavation sequences of two-arch tunnel. It was also observed that stress distributed eccentrically at the pillar as well as at the base of pillar. It is necessary to consider this point for the design of two-arch tunnel.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.257-268
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• 2005

In situ rock mass is generally heterogeneous and discontinuous, with varying degrees of strength along the planes of weakness. The planes of weakness such as joints, faults, cracks and bedding planes, control the strength and deformation characteristics of the rock mass. Subsequently, the stability of underground opening depends upon the spatial distribution of discontinuities and their mechanical properties in relation with geometrical shape of openins as well as the mechanical properties of intact rock materials. Understanding the behaviour of a discontinuous rock mass remains a key issue for improving excavation design in hiかy stressed environments. Although recent advances in rock mechanics have provided guidelines for the design of underground opening in isotropic rock mass, prediction and control of deformation in discontinuous rock masses are still unclear. In this study, parametric study was performed to investigate the plastic zone size, stress distribution and deformation behavior around underground opening in a discontinuous rock mass using a continuum joint model. The solutions were obtained by an elasto-plastic finite difference analysis, employing the Mohr-Coulomb failure criteria. Non-associated flow rule and perfectly plastic material behavior are also assumed.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.175-185
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• 2007

When filling material such as clay is included along the discontinuity, it may cause instability on a slope even if the direction of discontinuity works in a positive way. In the study area, slope sliding occurred at the boundary between a clay filling material and weathered soil because the physical properties differ across the boundary; and this is very similar to the situation where foliation in a rock works as a weak zone during a structural behavior, causing an inter-layer slip. In most analysis, if there exists a clay filling material, a single discontinuity is assumed to perform analysis. In those cases, the discontinuity is modeled as a slip surface within clay. Therefore, the characteristics of the boundary are not considered in the analysis, so that ultimately the physical property of clay usually prevails. The result of evaluating the slope stability affected by clay filling material shows the significant difference in the safety level due to the strength parameter depending on the failure type of the discontinuity by a filling material.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1995.03a
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• pp.41-47
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• 1995

NATM공법에서 지보는 주로 암반반응곡선(Ground Reaction Curve, GRC)상에서 설계된다. 그러나 GRC는 유도과정에서 많은 가정을 지니고 있어 시공에 직접 반영하기에는 많은 한계를 지닌다. 특히 과지압에 의한 소성거동의 문제가 심각하지 않고, 암반의 거동이 불연속면에 영향을 많이 받는 지역에서는 GRC의 가정 중에 하나인 등방 연속체라는 가정은 큰 결점 중의 하나이다. (중략)