초록 ▼

최종목표
○ 1 km급 심부 열-수리-역학적 연계특성 평가기술 개발
- 심부 수리특성 평가기술 개발
- 심부 암반응력 평가기술 개발
- 심부암반 장기 파괴거동 분석 기술 개발

개발내용 및 결과
○ 압력변화와 절리구조에 따른 수리 실험 및 영향분석
○ 수리전도도 평가를 위한 전기신호 측정실험 및 영향분석
○ 고심도 암반 그라우트 유동실험과 분석
○ 암반절리내 점성유체 주입에 대한 실내실험 기반 성능예측 수치해석과 민감도 분석
○ 고온, 고압, pH 조건에서 균열암석의 투수특

최종목표
○ 1 km급 심부 열-수리-역학적 연계특성 평가기술 개발
- 심부 수리특성 평가기술 개발
- 심부 암반응력 평가기술 개발
- 심부암반 장기 파괴거동 분석 기술 개발

개발내용 및 결과
○ 압력변화와 절리구조에 따른 수리 실험 및 영향분석
○ 수리전도도 평가를 위한 전기신호 측정실험 및 영향분석
○ 고심도 암반 그라우트 유동실험과 분석
○ 암반절리내 점성유체 주입에 대한 실내실험 기반 성능예측 수치해석과 민감도 분석
○ 고온, 고압, pH 조건에서 균열암석의 투수특성 변화 규명
○ 1 km급 수압파쇄시험장비 개발
○ 3차원 암반응력 측정장치 개발
○ 암반의 변형/응력특성 평가를 위한 굴착변위 기반의 탄성역해석 툴 개발
○ 지층특성 공간분포 추정을 위한 방법론 고찰
○ 한반도 응력자료의 Quality rank에 기반한 응력텐서 특성화
○ 암반의 장기 안정성 평가 시험과 AE 신호 분석
○ 암반 장기거동 2차원 해석모델 개발
○ 이축압축 모델실험과 입자결합모델에 의한 결과 비교검토
○ 고심도 조건하 지하공동의 발파굴착 안정성 해석모델 개발
○ 단층대 전단거동 예측을 위한 THM 해석모델 개발 및 검증

기대효과
○ 심부 지오시스템 특성 규명을 통한 지구환경/에너지자원산업분야 기반기술 확보(환경위해물질 차폐, 신재생에너지 개발)
○ 전 지구적 에너지/환경 문제해결 및 지각재해에 대한 안전확보와 국민편익 증진
○ 심부 Bio-Geo-Physics 관련 융복합 연구기회 확대 및 신산업·신시장 개척을 위한 미래성장동력 창출 기회 확보

적용분야
○ 심지층공간 구축을 위한 타당성 조사 및 부지선정
○ 심지층 에너지저장(CNG/CAES) 및 지하연구시설(천체우주물리관측 실험실)과 같은 중요 심지층공간의 Long-term 안전설계
○ 방사성폐기물, 심부 지열, 셰일가스, CO2 지중저장, 심부 채광

Abstract ▼

Ⅳ. Results of the Work
To propose the hydro-mechanical correlation considering nonlinear flow and evaluate the cubic law under deep depth condition, the permeability tests and effect analysis were performed according to deep depth condition (high water pressure, high stress) and fracture geometry

Ⅳ. Results of the Work
To propose the hydro-mechanical correlation considering nonlinear flow and evaluate the cubic law under deep depth condition, the permeability tests and effect analysis were performed according to deep depth condition (high water pressure, high stress) and fracture geometry (roughness). Three dimensional roughness of rock fractures was measured using laser scanner and quantitatively analyzed by JRC calculation process. Radial equation was derived for estimating hydraulic aperture and rock permeability, and the influence of pressure and roughness on permeability was examined. We proposed nonlinear hydro-mechanical empirical equation, which will be applied to the evaluation of rock permeability under deep depth environmental condition.

An electrical resistivity measurement system and a monitoring program were designed and constructed for precise estimation of hydraulic conductivity under a deep depth rock condition. Electrical resistivity tests were performed with various joint shapes (aperture size, joint wavelength, and joint roughness amplitude). The experimental data was analyzed to obtain the relationship between the resistivity and joint shape. The results of the measurement suggested that the designed monitoring system would obtain the electrical resistivity data with assured reliability.

We conducted flow tests using the developed rock grout injection equipment. Through the measurement of viscosity change, the time-dependancy of grout flow was experimentally analyzed, and the effects of the experimental parameters (w/c ratio, aperture size and injection flow rate) were examined. Penetration pattern and velocity of injected grouts were quantitatively evaluated by analysis of visual data using digital camera. The experimental results were used for verifying the numerical model of grout injection performance. Moreover, we participated in the intranational collaboration-TIGHT project and exchanged opinions.

Numerical method to simulate a penetrating flow and hydro-mechanical behavior of jointed rock mass induced by viscous fluid injection was developed. Using the developed method, sensitivity analysis of design parameters (injection grout properties, geological characteristics of the jointed rock mass, injecting conditions and the characteristics of mechanical deformation of joint) was conducted to investigate their influences on injection performance (penetration length and injection rate). The numerical estimation of a grout penetration length was well comparable to laboratory experiments using a cement-based grout and analytical solution.

The circulation-flow experiments on using the granite samples were conducted to examine the change in the fracture permeability at pH 7.61 and at 20°C with a confining pressure of 5 MPa. The result showed the similarity of decrease in permeability compared to the previous one-way flow experimental results, but the amount of decrease is relative low. The predictions are slightly higher than the measurements. This mismatch may be the result of either an unaccounted contribution of the precipitation at the fracture void walls or from an underestimation of the assumed fracture contact area. The developed coupled T-H-M-C model was improved by considering the undefined coupled processes such as hydro-mechanical interactions.

A hydraulic fracturing equipment to measure in-situ stress at a depth of 1 km was designed and partially manufactured. A literature review on deep-depth rock condition was carried out to determine the detailed specifications of the equipment. By making modifications to the existing equipment of KIGAM that was applicable to shallow depth < 500 m, the specifications of a new equipment was customized to deep-depth rock condition, and finally determined.

A pilot equipment to measure in-situ rock stress has been developed to substitute and improve a conventional one. The equipment consists of data storage and measuring modules. Data storage module equipped with data logger can save strain reading in a consecutive way. Furthermore, since the module includes a triggering system for piston sliding and a gyroscope for the identification of gage orientation, accuracy and convenience of measuring work on place could be improved.

The present study developed a back analysis tool in combination with a successive response surface method and a continuum numerical analysis code FLAC2D, which can be used for estimating the deformation modulus and stress ratio of the rock mass around underground excavations. The search algorithm adopted in the tool was optimized to improve the accuracy and computational efficiency in parameter identification. From a performance evaluation of the developed tool, it was demonstrated that the present approach could produce satisfactory results in parameter estimation and computational efficiency, which confirms its usefulness in assessing the mechanical characteristics of rock mass at depth.

The spatial distribution of the thickness of consolidation layer of Songdo International City is estimated using simple, ordinary, and universal kriging techniques, and the reliability of estimated results is analyzed. It is shown that the consolidation layer thickness estimated by the simple kriging technique is larger than those by other kriging techniques when the location of estimation is far from the locations where the measured data exist. In this case, the reliability of the simple kriging technique is observed to be lower than those of other techniques. Universal kriging gives a negative value for thickness of consolidation layer in some locations away from the data. It is concluded that the ordinary kriging is the most optimized estimation technique because the reliability of ordinary kriging technique is higher than those of other ones and the consolidation layer thickness estimated by the ordinary kriging locates within the reasonable range.

The hydraulic fracturing stress measurement data in Korea was compiled and classified based on World Stress Map quality ranking scheme, and the integrated directional statistics analysis was conducted. Shallow stress field in Korea is characterized by E-W or ENE-WSW maximum horizontal stress, analogous to deep crustal stress derived from earthquake focal mechanism inversion. However, it is evident that the stress direction rotates locally in a mountainous region in Gangwon, possibly due to topographic effect. The present-day stress field exhibits no clear correlation with old tectonic structures and is rather affected by mechanical properties of rock where stress measurements are carried out.

Mode II subcritical crack growth tests were carried out by combining developed mode II fracture toughness test, Short Core in Compression (SCC) with probabilistic SCG test concept using granite. The SCG parameters n and A were obtained and compared with those of mode I test. It was also confirmed that damage accumulation during the delayed failure of rock can be visualized by acoustic emission. Basic information on the criteria of long-term stability monitoring was obtained through the AE feature analysis.

A conceptual model simulating the process of subcritical crack growth has been analyzed and implemented using a two-dimensional finite difference analysis code. The process of crack initiation, stress redistribution, and fracture in a rock under uniaxial compressive condition has been simulated over time. The numerical model scheme has been used to investigate the lifetime and fracture pattern of a underground pillar under load.

Thermal cracking experiments for granite block samples using AE method showed a small amount of thermal cracks occurred inside model where the temperature was raised to about 90°C from the central heat source. The PFC numerical analysis considering the mechanical properties and individual thermal properties of each minerals showed the temperature distribution and characteristics of thermal cracking similar to the model experiments. In the case of numerical simulation considering biaxial loading conditions, larger number of thermal cracks were generated perpendicular to the low load direction, and tensile cracks were dominant.

For simulating structures or rock masses subjected to blast loads in LS-DYNA,two different methods were used to simulate the blast excavation of an underground gangway in the present study: one is a Lagrangian approach, and the other is an ALE (Arbitrary Lagrangian Eulerian) method. The calculated pressure is directly applied to blasthole wall elements in a Lagrangian approach, whereas the explosive as well as the air are explicitly modeled in an ALE method. The ALE method with node non-sharing technique is found to be a good choice to simulate explosion within rock mass since there can be a problem of solver down due to large deformation of the elements surrounding the explosive in the case of the Lagrangian approach that directly apply the explosion pressure to the element surfaces.

As part of the DECOVALEX-2019 project, an international research and model comparison collaboration for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical processes in geological systems, we have carried out Task B - fault slip modelling. The coupled hydro-mechanical behavior related to the fault activation induced by pressure injection was represented using TOUGH-FLAC simulator. A coupling module to update the changes in both geometrical features and hydrological properties caused by the mechanical deformations were included in the simulator. The numerical results from the preliminary benchmark simulation showed moderately good agreement with those obtained by other research teams. This benchmark study will be progressed and enhanced by continuing collaboration and interaction with the research teams until April 2017.

목차 Contents

• 표지 ... 1제 출 문 ... 2최종보고서 요약서 ... 4요 약 문 ... 5SUMMARY ... 11CONTENTS ... 19목차 ... 21제1장 연구개발과제의 개요 ... 24 제1절 연구개발의 목적 및 필요성 ... 24 1. 연구개발의 목적 ... 24 2. 연구개발의 필요성 ... 24 제2절 연구개발 범위 ... 25제2장 국내외 기술개발 현황 ... 30 제1절 심지층 지하공간 활용 현황 ... 30 1. 국외 현황 ... 30 2. 국내 현황 ... 39 제2절 심부 지오시스템 핵심 평가기술 현황 ... 43 1. 국외 기술개발 현황 ... 43 2. 해외 유관기관 주요 연구개발 현황 ... 47 3. 국내 기술개발 현황 ... 52 제3절 심지층공간 활용을 위한 심부 지오시스템 특허 현황 ... 56 1. 기술개발 분야 특허 동향 ... 56 2. 국가별 특허 동향 ... 56 3. 기술별 동향 ... 57제3장 연구개발수행 내용 및 결과 ... 60 제1절 심부 수리특성 평가기술 개발 ... 60 1. 압력변화와 절리구조에 따른 수리실험 및 영향분석 ... 60 2. 수리전도도 평가를 위한 전기신호 측정실험 및 영향분석 ... 70 3. 고심도 암반 그라우팅 유동실험과 분석 ... 83 4. 암반절리 내 점성유체 주입에 대한 실내실험 기반 성능예측 수치해석과 민감도 분석 ... 96 5. 고온, 고압, pH 조건에서 균열암석의 투수특성 변화 규명 ... 129 제2절 심부 암반응력 평가기술 개발 ... 143 1. 1 km급 수압파쇄 시험장비 설계 및 일부 제작 ... 143 2. 3차원 암반응력 측정장치 개발 ... 147 3. 암반의 변형/응력특성 평가를 위한 굴착변위 기반의 탄성역해석 툴 개발 ... 157 4. 지층특성 공간분포 추정을 위한 방법론 고찰 ... 166 5. 한반도 응력자료의 Quality rank에 기반한 응력텐서 특성화 ... 174 제3절 암반 장기 파괴거동 분석기술 개발 ... 193 1. 암석의 장기 안정성 평가 시험과 AE 신호 분석 ... 193 2. 암반 장기거동 2차원 해석모델 개발 ... 213 3. 이축압축 모델실험과 입자결합모델에 의한 결과 비교검토 ... 224 4. 고심도 조건하 지하공동의 발파굴착 안정성 해석모델 개발 ... 232 5. 단층대 전단거동 예측을 위한 THM 해석모델 개발 및 검증 ... 239제4장 목표달성도 및 관련분야에의 기여도 ... 258 제1절 목표달성도 ... 258 1. 최종 연구목표의 달성도 ... 258 2. 당해연도 목표의 달성도 ... 259 제2절 관련분야에의 기여도 ... 261 1. 기술적 측면 ... 261 2. 경제․산업적 측면 ... 261 3. 정책적 측면 ... 261제5장 연구개발결과의 활용계획 ... 264제6장 연구개발과정에서 수집한 해외과학기술 정보 ... 266 제1절 해외 연구동향 ... 266 제2절 논문 ... 269제7장 참고문헌 ... 278끝페이지 ... 288