• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.161-172
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• 2000

자연암석절리 및 인공 절리에 대하여 일정수직응력제어, 일정 수직하중제어 그리고 무한 강성제어가 가능한 암석 절리면 전단기 시험기를 개발하였다. 이 시험기는 전단변위에 의한 첩촉면적의 변화량을 계산하여 하중변화량을 조절하여 일정수직응력상태를 유지한다. 수직하중에 따른 시험기 강성에 의한 변화향이 제어 프로그램 내에서 제어되어 순수한 시편의 변위량을 출력하도록 하였다. 전단하중에 따른 시험기 강성에 의한 변위량은 상, 하부 전단상자의 상대변위 측정으로 최소화하였다. 전단거동 중의 자유도는 전당방향에 대하여 수평이도, 연직이동, 피칭, 롤링이 가능하도록 하였다. 자연절리면을 모사한 석고시편에 대하여 일정 수직응력 제어, 일정수직하중제어 그리고 무한 강성제어 조건으로 시험하여 제어상태 검증 및 비교를 하였다. 또한 경사각이 16.7˚와 22.6˚인 톱니형 시편에 대하여 시험한 결과 경사각 16.7˚와 22.6˚는 JRC로 10과 15를 나타내었으며, 첨두팽창각이 첨두전단강도에서 발생되며, Barton의 모델과 잘 일치함을 보였다.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.147-157
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• 2003

The characteristics of a rock joint which influence the stability of rock mass structures such as cut slopes and tunnels are largely controlled by the conditions of the rock joint as well as its boundary conditions. The conditions of rock joints comprise asperity strength, roughness, and filling materials. Boundary conditions can be represented by assuming that the deformability(or stiffness) of the rock mass surrounding the joints is modelled by a spring with stiffness. A new direct shear apparatus was developed in this study, which adapts a servo control system using PID algorithm. This apparatus can be used to investigate the various aspects of shear characteristics of the rock joints at conditions of constant normal stress and constant normal stiffness and so on. The test results for saw-cut teeth joints show that shear strength should be evaluated by considering its specific boundary conditions far the design of tunnels and cut slopes.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.57-64
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• 2001

암석-콘크리트 불연속면의 전단변형 및 파괴특성을 규명하기 위해 상부 재료를 콘크리트로, 하부 재료를 암석으로 하는 규칙.불규칙 톱니형 시료와 인공 절리시료를 제작하여 실험실 직접전단시험을 실시하였다. 전단과정 동안 하중과 변위 외에 미소파괴음의 계수와 에너지를 측정하여 전단과정의 단계별 특징을 규명하였고 미소파괴음 음원추적을 실시하여 불연속면에서의 거칠기 파괴부분의 변화를 고찰하였다. 또한 암석 불연속면과 암석-콘크리트 불연속면의 거동을 비교하고 거칠기의 불규칙성 증가에 따른 전단거동의 변화를 관찰하였다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.265-270
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• 2000

AESTRACI: The shmr behior of sawtoothed artrjicial joints grouted with cement milk rm investiguted in the lahotconstant normal stress conditions. Tests were amducted on joints with asperities h i n g inclinations cf 16.7" and 26.6" ,strengths h i n g 15MPa and 47MPa under a given nmge of n o d stresses wrying frcm 0.76 to 1.g MPa md at a freepitching, rolling and dihtmuy. Results show that the gect of asperities on shmr strength increme is signifamt up to as,to grout thidness (t/a) mtio 4 0.3-1.0. Increme of ahesim is the nmn muse cf shmr strength increme in cemmtoothed artificial iointsed artificial ioints

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.721-728
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• 2000

The shear behavior of sawtoothed artificial joints grouted with cement milk was investigated in the laboratory under constant normal stress conditions. Tests were conducted on joints with asperities having inclinations of 16.7$^{\circ}$ and 26.6$^{\circ}$, compresive strengths having 15MPa and 47MPa under a given range of normal stresses varying from 0.76 to 1.91 MPa and at a free condition of pitching, rolling and dilatancy. Results show that the effect of asperities on shear strength increase is significant up to asperity height to grout thickness (t/a) ratio of 0.3∼1.0. Increase of cohesion is the main cause of shear strength increase in cement grouted sawtoothed artificial joints.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.447-457
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• 2008

Laboratory tests for single plane sliding were conducted using the model rock slope to investigate the cut slope deformability and failure mechanism due to combined effect of engineering characteristics such as angle of sliding plane, water force, joint roughness and infillings. Also the possibility of prediction of slope failure through displacement monitoring was explored. The joint roughness was prepared in forms of saw-tooth type having different roughness specifications. The infillings was maintained between upper and lower roughness plane from zero to 1.2 times of the amplitude of the surface projections. Water force was expressed as the percent filling of tension crack from dry (0%) to full (100%), and constantly increased from 0% at the rate of 0.5%/min and 1%/min upto failure. Total of 50 tests were performed at sliding angles of $30^{\circ}$ and $35^{\circ}$ based on different combinations of joint roughness, infilling thickness and water force increment conditions. For smooth sliding plane, it was found that the linear type of deformability exhibited irrespective of the infilling thickness and water force conditions. For sliding planes having roughness, stepping or exponential types of deformability were predominant under condition that the infilling thickness is lower or higher than asperity height, respectively. These arise from the fact that, once the infilling thickness exceeds asperities, strength and deformability of the sliding plane is controlled by the engineering characteristics of the infilling materials. The results obtained in this study clearly show that the water force at failure was found to increase with increasing joint roughness, and to decrease with increasing filling thickness. It seems possible to estimate failure time using the inverse velocity method for sliding plane having exponential type of deformability. However, it is necessary to estimate failure time by trial and error basis to predict failure of the slope accurately.