초록 ▼

$\circ$ 1차년도 선정된 광산의 지하 500-600 m 심도 및 100-200 m 심도에 실험준비 갱도 굴착, 모니터링 실 굴착, 갱도 내 시추 및 수압파쇄 시험에 의한 초기지압 계측
$\circ$ -363 ML(지하 500-600 m)에 MS 계측시스템 설치
$\circ$ 저온 열균열 현상을 이용한 신개념의 현지암반응력측정 기법의 개발 및 수치해석적 검증(국내특허출원)
$\circ$ 불연속면처리 프로그램의 기능 확장(자료처리, 불연

$\circ$ 1차년도 선정된 광산의 지하 500-600 m 심도 및 100-200 m 심도에 실험준비 갱도 굴착, 모니터링 실 굴착, 갱도 내 시추 및 수압파쇄 시험에 의한 초기지압 계측
$\circ$ -363 ML(지하 500-600 m)에 MS 계측시스템 설치
$\circ$ 저온 열균열 현상을 이용한 신개념의 현지암반응력측정 기법의 개발 및 수치해석적 검증(국내특허출원)
$\circ$ 불연속면처리 프로그램의 기능 확장(자료처리, 불연속면 추출 및 분석 인터페이스 기능 보완)
$\circ$ 굴착 영향권 손상모델(UDEC-DM 모델) 개발 및 calibration
$\circ$ 손상대 평가 목적의 방향 탐지 안테나를 이용한 레이더 탐사기법의 현장적용실험 실시

Abstract ▼

The limitations of surface-based and traditional laboratory investigations have led to the recognition that studies of rock formations to host potential repositories must include studies at the excavation scale in the underground environment. Short-term tests on standard laboratory specimens cannot

The limitations of surface-based and traditional laboratory investigations have led to the recognition that studies of rock formations to host potential repositories must include studies at the excavation scale in the underground environment. Short-term tests on standard laboratory specimens cannot be used to determine how a large underground excavation will deform over a period of months, years or longer. In-situ scale of underground research laboratories have been constructed in several countries to address the fundamental questions on whether or not a particular rock type or rock mass would be suitable as a repository host medium. It is no doubt that URL would contribute to the increase in the public understanding of construction of repository for HLW.
The objectives of this project are to design URL and to develop a core technology for utilization of underground at depths. It is a generic URL. Due to a budget restriction, URLs are planned to be placed at currently running mines. A mine was chosen and access tunnels for future experiments have been excavated at depths of -500 to 600 ML and -100 to 200 ML. In-situ stress measurements were performed using a hydraulic fracturing method.
Major R&D works in rock mechanics area are focused on the development of new technique for in-situ stress measurement to overcome some of the disadvantages in the current techniques; assessment of the excavation disturbed zone (EDZ), which is important for the support requirements and for the long-term safety of a repository for geological disposal of radioactive waste.
Knowledge of virgin earth stresses is now-a-days considered to be an essential pre-requisite for construction of important underground and open-pit excavations such as mines, tunnels, caverns etc. It is a vital input parameter in numerical modeling studies for stability analysis and design. Direction and magnitude of earth stresses are also important parameters to study tectonic stresses for the prediction of earth quakes and seismic events. The current in-situ stress measurement techniques include borehole fracturing methods such as hydro-fracturing, sleeve fracturing and borehole jacks stress relieving techniques such as over-coring and borehole slotting borehole breakout measurements; indirect methods such as acoustic emission measurements etc. Some of the above techniques such as the hydro-fracturing and over-coring have gained popularity and have undergone various technological advancements in the recent decades. The new method suggested herein attempts to overcome some of the disadvantages in the current techniques. The invention includes a novel concept, methodology and devices involved. This novel concept is basically a combination of borehole stress relieving and borehole fracturing techniques, by means of inducing thermal tensile stresses at the borehole periphery by the use of a cryogenic fluid such as Liquid Nitrogen. The borehole wall eventually develops fractures when the induced thermal stresses exceed the existing compressive stresses at the borehole periphery in addition to the tensile strength of the rock. The thermal stresses shall be induced uniformly in all directions from the center of the borehole. Since the stresses existing at the periphery of the borehole wall are different through out the circumference, the cracking is expected to take place at different temperatures in different directions. The pre-existing stresses can thus be evaluated from the temperatures of crack development.
One of the challenges for constructing a deep geological repository is estimating the constructability, i.e., support requirements. Balancing the support requirements with the isolation requirements(repository depth) can only be achieved if the properties of the rock mass can be evaluated with confidence. This evaluation is difficult for any type of rock mass as input data have to be inferred from standard laboratory tests. The test samples are in general of relative small size and do not represent the rock heterogeneity and the influence of potential discrete features or discontinuities. Therefore, scaling procedures are necessary in any rock type to evaluate deformation and fracturing associated with tunnelling. During tunnel construction new surfaces will be created leading to significant changes in the local stress field as for continuity reasons stresses normal to the interface (e.g. radial stress in a cylindrical tunnel) have to vanish at the interface while tangential stresses may increase significantly. In other words, the confining stress becomes zero and the other stress component increases which may lead to local failure under extension and/or shear, Such processes may be accelerated by hydro-mechanically coupled processes. Areas around underground excavation affected by such processes are generally called excavation disturbed or damaged zone(EDZ). There is now an international consensus to relate the definition of the EDZ with processes, which are important for the long-term safety of a repository for geological disposal of radioactive waste. It was recognized that it was important to differentiate the EDZ from the EDZ with regard to their flow and transport characteristics, admitting that areas of hydro-mechanical and geochemical modifications with major changes in flow and transport properties should be distinguished from those without negative effects on the long-term safety. In this year 1 progress reporting period we have compiled data from three in situ experiments. All of these experiments have documented the factors that contribute to the formation of the EDZ and have attempted to measured the EDZ using various techniques.
The borehole radar reflection technique using a directional finding antenna was applied to the URT site for assessment of excavation disturbed zone. A monitoring system for micro-seismic events was installed at -363 level and data acquisition is in progress.

목차 Contents

• 제 1 장 연구개발과제의 개요...18
• 제 1 절 연구개발 목적 및 필요성...18
• 제 2 절 연구개발의 내용 및 범위...19
• 제 2 장 국내외 기술개발 현황 분석...22
• 제 1 절 지하연구실험실을 이용한 R&D...22
• 제 2 절 초기응력 측정 기술...26
• 제 3 절 원격암반특성처리 프로그램...26
• 제 4 절 시추공 레이더 탐사를 이용한 손상대 및 지반물성 파악기술...27
• 제 3 장 연구개발수행 내용 및 결과...32
• 제 1 절 지하연구실험실(URL) 구축...32
• 제 2 절 저온 열균열 현상을 이용한 신개념 초기 지압 측정법 개발...52
• 제 3 절 원격암반특성처리 프로그램 개발...69
• 제 4 절 균열암반에서의 굴착손상영역권(EDZ) 정량화에 관한 기법 개발...93
• 제 5 절 불연속 암반내 굴착손상영역에서의 지하수 유동에 관한 수치해석적 연구...110
• 제 6 절 시추공 레이더 탐사를 이용한 손상대 및 지반물성 파악기술...151
• 제 4 장 목표 달성도 및 관련분야에의 기여도...160
• 제 1 절 목표달성도...160
• 제 2 절 관련분야에의 기여도...161
• 제 5 장 연구개발결과의 활용 계획...162
• 제 6 장 연구과정에서 수집한 해외과학기술 정보...163
• 제 7 장 참고문헌...164
• 부록...170
• 부록 1. URL 구축 지역 암석물성시험 자료...172
• 부록 2. 시추 조사 자료...180
• 부록 3. 현장 수압파쇄시험...201