• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.241-247
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• 2001

절리가 발달한 암반사면의 경우, 토사사면의 안전율 평가를 위해 널리 이용되는 한계평형법을 이용한 해석법은 파괴 활동면을 가장할 수 없기 때문에 사용이 곤란하다. 한편, 비등방 탄소성 모델(편재절리모델)을 사용하여 2조의 절리군을 가진 암반사면의 안전율을 계산할 수 있는 방법이 개발되었지만, 이 방법은 개별절리를 효과적으로 고려하지 못한다. 본 연구에서는 개별절리를 고려한 불연속체 해석에 의한 암반사면의 안정성 해석시 사면의 안전율을 평가하는 기법을 개발하였다. 이를 위해, 절리 전단강도 감소기법을 적용하였으며, UEDC의 내장 언어인 FISH를 사용하여 프로그램을 개발하였다. 또한 실제 절리 암반사면을 대상으로 절리를 측정하고, 개발된 기법에 의한 사면의 안전율을 구하였으며, 동일한 사면에 대해 등가연속체로 가정한 편재절리모델 해석을 수행하여 결과를 비교하였다.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.45-51
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• 2003

Grouting materials in rock is grouted as vein type along the fault surface by the other way for soil and allow a change of characteristics in rock faults as a result of that. Therefore the deformation characteristics of rock faults after grouting differ as a direction and characteristic of grouted fault and stress condition of field rock. Thereby it must be analyzed the effect for deformation of rock according to characteristics of rock faults and characteristics of grouting materials to accurately evaluate the reinforced effect by grouting. But grouting method used in field until present depends on experience of workers, and inspection for those effects are evaluated by measurement of elastic wave velocity, permeability tests and etc. in field. In this study, it was investigated that the effects for shear characteristics of maximum shear strength, residual shear strength and etc. by comparison and analysis of test results which were worked by direct shear tests of rock faults with changing a type of grouting materials and the grouting depth(t) for average width(a) of fault surface roughness when OPC(Ordinary Portland Cement) and Micro cement was grouted in fault surface of field rock to evaluate characteristicsof the shear deformation for rock fault surface of dam by grouting.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.439-449
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• 2011

The characteristics of rock fractures for engineering rock classification are investigated by analyzing three dimensional point cloud generated from adjusted digital images of a tunnel face during construction and the tunnel is reinforced based on the supporting pattern suggested by the RMR and the Q system using parameters extracted from those images. As results, it is possible saving time required from face mapping to tunnel reinforcing work, enhancing safety during face mapping work in tunnels and reliability of both the mapping information and selecting supporting pattern by storing the files of digital images and related information which can be checked again, if necessary sometime in the future.

• Tunnel and Underground Space
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• v.17 no.4
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• pp.322-331
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• 2007

Hundreds of rock slopes are constructed along the road, highway and railroad in mountainous Kangwon province and managed by each authorities concerned. It is practically not possible to carry out detailed rock slope investigation owing to the tremendous number of slopes and budgetary limit. Therefore, it is reasonable to perform a step-by-step investigation consisted of basic and detailed survey program and practical rock slope hazard assesment method for person in charge is strongly required. Through the development and application of KSMR (Korean Slope Mass Rating), it was found that KSMR could be practically used as an alternative of SMR though the number of inputs were reduced. In addition, the difference of hazard assessment between KSMR and experts decreased in case of considering the height of slope.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.1-11
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• 2001

The geological characteristics of Korea are that we can encounter the rock layer only after 10m of excavation, methods to presume the rock pressure distribution of the rock layer is urgently needed. When using the existing empiric science of Terzaghi-Peck, Tschebotarioff to measure the rock pressure of the rock layer, underestimate the real strength because of the cohesion is ignored. Therefore calculating the horizontal sliding force of wedge block, which includes the dips and shear strength of discontinuities and surcharge load etc., think to be to getting a closer rock stress of the real rock pressure acting upon the earth structure in rock mass. This research use Coulomb soil pressure theory assuming that the backfill soil will yield wedge failure when it has cohesion, applying Prakash-Saran(l963), and then it uses equilibrium of force and shear strength $\tau$=c+$\sigma$tan $\Phi$ of the cliscontinuities. Analyzing shear strength and dips of cliscontinuities using calculated theory according to the status of discontinuities aperture, we were able to find out that because the cohesion and friction angle of the rock layer itself is large enough, how the dip directions and dips facing the excavation face is the only factor deciding whether or not the rock stress is applied. The evaluated theory of this research should be strictly estimated, so that the many parameters such as c, $\Phi$value, types and structures of rock class, excessive lateral pressure, dynamic load, earthquake, needed later when calculating shear strength of discontinuities and especially the ground water effect acting on rock layer should be coumpted with many measuring data achieve at the insite to study the application.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.622-640
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• 2009

원유 비축기지 저장공동과 같이 상하로 긴 형상의 대규모 공동에서 횡방향의 지압이 과도하게 작용하면 천정부의 응력집중과 측벽의 암반 변위가 과도하게 발생하여 저장공동의 불안정 요인이 된다. 특히 지압의 절대 크기가 암반 강도의 일정 비율 이상이 되면 응력 집중에 의한 암반의 취성 파괴를 유발하고, 이러한 현상은 터널 굴착 시 발생하는 파괴음(popping)과, 굴착면에 평행한 형태로 암편이 탈락하는 취성파괴(spalling) 현상을 동반한다. 이 글에서는 대규모 지하저장공동 굴착시 실제 발생한 과지압으로 인한 문제 사례에 대해 소개한다. 저장공동 굴착시 관찰된 암편 및 숏크리트 탈락과 균열 발생 현상을 관찰하고 암반 계측결과 분석을 통해 과지압의 현상을 진단하였다. 과지압 구간의 현재 상태 및 원안 설계안에 대해 연속체 및 불연속체 안정성 해석을 실시하여 문제의 심각성을 평가하였다. 이를 통해 굴착 형상 변경 및 특수 보강 방안을 제안하였으며 제안된 안의 보강효과에 대한 수치해석 평가 결과를 재검토 하였다. 이들 결과를 종합하여 과지압구간 보강안을 도출하였으며 상시 안정성 감시 대책으로 현장 암반의 미소파괴음 계측 방안을 제시하였다.

• Explosives and Blasting
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• v.30 no.2
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• pp.29-42
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• 2012

Variables influencing the free face movement due to rock blasting include the physical and mechanical properties, in particular the discontinuity characteristics, explosive type, charge weight, burden, blast-hole spacing, delay time between blast-holes or rows, stemming conditions. These variables also affects the blast vibration, air blast and size of fragmentation. For the design of surface blasting, the priority is given to the safety of nearby buildings. Therefore, blast vibration has to be controlled by analyzing the free face movement at the surface blasting sites and also blasting operation needs to be optimized to improve the fragmentation size. High-speed digital image analysis enables the analyses of the initial movement of free face of rock, stemming optimality, fragment trajectory, face movement direction and velocity as well as the optimal detonator initiation system. Even though The high-speed image analysis technique has been widely used in foreign countries, its applications can hardly be found in Korea. This thesis aims at carrying out a fundamental study for optimizing the blast design and evaluation using the high-speed digital image analysis. A series of experimentation were performed at two large surface blasting sites with the rock type of shale and granite, respectively. Emulsion and ANFO were the explosives used for the study. Based on the digital images analysis, displacement and velocity of the free face were scrutinized along with the analysis fragment size distribution. In addition, AUTODYN, 2-D FEM model, was applied to simulate detonation pressure, detonation velocity, response time for the initiation of the free face movement and face movement shape. The result show that regardless of the rock type, due to the displacement and the movement velocity have the maximum near the center of charged section the free face becomes curved like a bow. Compared with ANFO, the cases with Emulsion result in larger detonation pressure and velocity and faster reaction for the displacement initiation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.37-44
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• 2018

This study proposed the modified weighting values for jointed rock slopes. The studies on deduction of evaluation index and calculation of weighting, development of criteria for evaluation and evaluation models have been conducted through decision making techniques such as the Delphi method and the AHP method by many researchers. Because these decisions making techniques may be less objective, it is necessary to calculate reasonable weighting considering both an objective weighting and a subjective weighting simultaneously. In this study, utilizing the inspection data of jointed rock slopes, an objective weighting that the concept of entropy is applied was calculated. And the subjective weighting values by AHP technique was calculated based on the opinion of experts. And a modified weighting was suggested by combining the two. As a result, it was found that jointed rock slopes have higher weighting in artificial factors and the damage status items. In addition based on the finally suggested weighting (mixed weighting), the revised evaluation criteria could be presented by converting it into the evaluation score (76 points). And it is expected that it could be usefully utilized upon inspections on cutting slopes and safety diagnosis since objective and highly reliable criteria compared to the condition evaluation criteria that are currently used could be presented through the results of the study.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.231-238
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• 2005

On the basis of flow resistance theory the conceptual model and related mathematical descriptions is proposed for resistance modeling of groundwater flow in CPM(continuum Porous medium), DFN(discrete fracture network) and fractured-porous medium. The proposed model is developed on the basis of finite volume method assuming steady-state, constant density groundwater flow. The basic approach of the method is to evaluate inter-block flow resistance values for a staggered grid arrangement, i.e. fluxes are stored at cell walls and scalars at cell centers. The balance of forces, i.e. the Darcy law, is utilized for each control volume centered around the point where the velocity component is stored. The transmissivity (or permeability) at the interface is assumed to be the harmonic average of neighboring blocks. Flow resistance theory was utilized to relate the fluxes between the grid blocks with residual pressures. The flow within porous medium is described by three dimensional equations and that within an individual fracture is described by a two dimensional equivalent of the flow equations for a porous medium. Newly proposed models would contribute to develop flow simulation techniques with various matrix characteristics.

• The Journal of Engineering Geology
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• v.12 no.3
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• pp.295-303
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• 2002

The stability of rock slopes is closely related to the factors such as: type of rock, development of geological structures, weathering, characteristics of rock, and the shape of the geological features. When we design the rock slope, the slope stability is determined by the discontinuity causing the circular, plane or wedge failure. The failure happens when the slope is under the unstable geological condition. But in some cases, slope failure has occurred even though the slope is under stable geological conditions. In this respect, this paper presents the plane failure conditions for domestic rock slopes through research of sites where slope failure has occurred regardless of whether or not it satisfied the stable geological conditions.