• Geomechanics and Engineering
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• 제7권4호
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• pp.375-401
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• 2014

It is generally accepted that material heterogeneity has a great influence on the deformation, strength, damage and failure modes of rock. This paper presents numerical simulation on rock failure process based on the characterization of rock heterogeneity by using a digital image processing (DIP) technique. The actual heterogeneity of rock at mesoscopic scale (characterized as minerals) is retrieved by using a vectorization transformation method based on the digital image of rock surface, and it is imported into a well-established numerical code Rock Failure Process Analysis (RFPA), in order to examine the effect of rock heterogeneity on the rock failure process. In this regard, the numerical model of rock could be built based on the actual characterization of the heterogeneity of rock at the meso-scale. Then, the images of granite are taken as an example to illustrate the implementation of DIP technique in simulating the rock failure process. Three numerical examples are presented to demonstrate the impact of actual rock heterogeneity due to spatial distribution of constituent mineral grains (e.g., feldspar, quartz and mica) on the macro-scale mechanical response, and the associated rock failure mechanism at the meso-scale level is clarified. The numerical results indicate that the shape and distribution of constituent mineral grains have a pronounced impact on stress distribution and concentration, which may further control the failure process of granite. The proposed method provides an efficient tool for studying the mechanical behaviors of heterogeneous rock and rock-like materials whose failure processes are strongly influenced by material heterogeneity.

• 터널과지하공간
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• 제4권1호
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• pp.38-46
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• 1994

This paper concerns the design of blasts adjacent to structures and facilities. In order to investigate the site characteristics, measurements of in-situ wave propagation and laboratory tests of rock cores taken from the boreholes were carried out. Effects of rock media and delay intervals on ground vibration levels were identified from over sixty measurements of three times of test blasts. For practical use in the field, an empirical propagation equation was derived so as to reflect the characteristics of rock media and delay effects. Safe limits of vibration level for structures were conservatively established based on various suggested criteria. Safe limits for facilities were adopted so that vibration levels induced by blasting should not exceed the allowable limits specified in the manufacturer's installation condition. Suggested were blast pattern and operation to enhance the rock fracturing and to reduce the ground vibration levels under the restricted conditions.

• 터널과지하공간
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• 제6권3호
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• pp.197-208
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• 1996

Due to the constraints in pre site-investigation for tunnel, it is essential to redesign the support structures suitable for rock mass conditions such as rock strength, ground water and discontinuity conditions for safe tunnel construction. For the selection of optimum support, it is very important to carry out the rock mass classification and in-situ measurement in tunnelling. In this paper, in a mountain tunnel designed by NATM in hard rock, the selectable system for optimum support has been studied. The tunnel is situated at Chun-an in Kyungbu highspeed railway line with 2 lanes over a length of 4, 020 m and a diameter of 15 m. The tunnel was constructed by drill & blasting method and long bench cut method, designed five types of standard support patterns according to rock mass conditions. In this tunnel, face mapping based on image processing of tunnel face and rock mass classification by RMR carried out for the quantitative evaluation of the characteristics of rock mass and compared with rock mass classes in design. Also, in-situ measurement of convergence and crown settlement conducted about 30 m interval, assessed the stability of tunnel from the analysis of monitoring data. Through the results of rock mass classification and in-situ measurement in several sections, the design of supports were modified for the safe and economic tunnelling.

• 한국터널지하공간학회 논문집
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• 제17권2호
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• pp.167-174
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• 2015

국토의 70%이상이 산악 지형인 우리나라에서는 지형적인 특성으로 터널 건설이 중요하며, 터널 건설의 증가로 안전한 터널 건설이 중요한 문제로 대두되고 있다. 최근, 도로의 고속화와 직선화로 인해 장대터널 건설이 증가하고 있다. 본 연구에서는 장대터널에서의 암반 블록의 수치 모델링을 이용한 터널 안전 시공법을 제안하고, 현장에서 관찰한 불연속면 정보를 근거로 하여 실제 장대터널에 적용했다. 실제 터널현장에 있어서, 암반 블록의 수치 모델링을 이용한 터널 안전 시공법을 위해서 새롭게 개발한 수치해석 프로그램을 사용하여 정확한 키블럭 추출이 가능한 것을 검증하였다. 사용하기 쉬운 사용자 인터페이스를 가지고 있는 본 컴퓨터 시뮬레이션 기법은 암반 블럭의 안정성 계산뿐만 아니라 추가 보강대책공의 설계도 가능하다.

• 건설안전기술
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• 통권50호
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• pp.84-96
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• 2009

Road is typically constructed along ridge area of mountain because of topographical and economic reasons. Therefore, road may face lots of open cut slope which can easily cause rock falling. This study evaluates the structural safety of newly developed falling rock protection system which has a roof deck plate. The structural performance under self-weight, snow load and load from failing rock was investigated using a finite element numerical analysis method. From the analysis results, the H-beam space was limited not to exceed 2.2m. The deck plate was also safe under the examined loading condition. A hinge and connection in the system were investigated through detailed modelling and analysis. The results showed that the hinge was safe enough and that the connection should strengthened with appropriate stiffeners.

• 한국안전학회지
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• 제24권3호
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• pp.47-53
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• 2009

Road is typically constructed along ridge area of mountain because of topographical and economic reasons. Therefore, road may face lots of open cut slope which can easily cause rock falling. This study evaluates the structural safety of newly developed falling rock protection system which has a roof deck plate. The structural performance under self-weight, snow load and load from falling rock was investigated using a finite element numerical analysis method. From the analysis results, the H-beam space was limited not to exceed 2.2m. The deck plate was also safe under the examined loading condition. A hinge and connection in the system were investigated through detailed numerical modelling and analysis. The results showed that the hinge was safe enough and that the connection should strengthened with appropriate stiffeners.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 토목섬유 특별세미나
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• pp.81-92
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• 2000

Green Slope(F.F.R : Fabric Form Reinforcement Method) is one of an environmental slope protection method at steep cutting sites. This method is that soil and rock at the steep slope is fixed using the environmental Fabric Form, Nail, Rock Bolt and Rock Anchor, And then, the surfaces covered with grasses or weeds. This method will be satisfied both safe slope protection and natural environment appearance. Green Slope is a useful method of the construction sites of steep cutting slopes.

• 방사성폐기물학회지
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• 제11권4호
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• pp.311-324
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• 2013

우리나라 중저준위 방사성폐기물 최종 처분시설인 월성원자력환경관리센터의 폐쇄 후 안전평가 컴퓨터 프로그램의 신뢰성 확보를 위해 MASCOT와 검증프로그램으로 SAFE-ROCK와 GOLDSIM을 선정하여 정상시나리오에 대하여 안전평가를 수행하였다. 각 프로그램의 장단점을 비교/분석하였으며, 각 프로그램 별 구획 간의 선량 및 누출량을 평가하였다. 그 중 방사성핵종 $^{129}I$와 $^3H$가 MASCOT와 SAFE-ROCK 프로그램에서는 비슷한 경향을 보여주었지만, GOLDSIM 프로그램에서는 상이한 결과를 나타냈다. 이는 각 프로그램의 근계지역 내 핵종이동방정식의 해석과정의 차이와 개별 프로그램의 한계로 인해 다른 결과값을 보여주는 것으로 분석되었다. GOLDSIM 프로그램의 경우, 선원항 구획에서 초기 핵종누출량은 time-scale에 민감하게 반응한다는 사실도 확인할 수 있었다. 안전평가 프로그램은 처분환경에서 발생하는 핵종거동 및 이동에 대한 실제현상을 예측하기 위해 모델링을 거치지만, 전산프로그램의 특성과 실제현상에 대한 데이터가 제한적이므로 결과에 차이가 발생하게 된다. 이러한 차이점은 다양한 프로그램을 이용한 결과와 상호비교를 통해 알아내며 그 원인을 지속적으로 분석하는 연구개발과정을 필요로 하고 있다.

• 터널과지하공간
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• 제2권1호
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• pp.102-115
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• 1992

Blasting operations associated with rock excavation work may have an environmental impact in nearby structures or human beings. With the increase of construction work in urban areas, vibration problems and complaints have also increased. In order to determine the optimum design parameters for safe blast, it is essential to understand blast mechanism, design variables involved in blast-induced damage, and their effects on the blasting results. This paper deals with the characteristics of ground vibrations, air blast and fly rock caused by blast, including the general method of establishing the vibration predictors, and damage criteria suggested by various investigators. The results of field measurements from open pit mine and tunnel construction work are discussed. Basic concepts of how to design blast parameters to control the generation of ground vibrations, air blast and fly rock are presented.

• 터널과지하공간
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• 제1권
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• pp.32-38
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• 1991

9 nuclear power plants are presently in operation in Korea. They produce radioactive waste of which the most long-lived radioactive elements need to be safely stored for hundreds of thousands of years, isolated from humanity and the environment. The safe disposal of high level radioactive waste in mined cavities requires knowledge of the mechanical. thermal and fluid flow characteristics of rock as perturbed by a thermal pulse The literature review was performed to assemble data on the following properties: modulus tensile strength compressive strength thermal expansion specific heat, thermal conductivity thermal diffusivity and permeability.