Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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A Study on Hydrogeological Characteristics of Deep-Depth Rock Aquifer by Rock Types in Korea

국내 암종별 고심도 암반대수층 수리지질특성 연구

  • Hangbok Lee (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Chan Park (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Dae-Sung Cheon (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Junhyung Choi (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources) ;
  • Eui-Seob Park (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources)
  • 이항복 (한국지질자원연구원 심층처분환경연구센터) ;
  • 박찬 (한국지질자원연구원 심층처분환경연구센터 ) ;
  • 천대성 (한국지질자원연구원 심층처분환경연구센터) ;
  • 최준형 (한국지질자원연구원 심층처분환경연구센터) ;
  • 박의섭 (한국지질자원연구원 심층처분환경연구센터 )
  • Received : 2024.08.05
  • Accepted : 2024.08.13
  • Published : 2024.08.31
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Abstract

In order to successfully select a site for deep geological disposal of high-level radioactive waste, it is important to perform the stepwise approach along with the systematic selection and survey of evaluation parameters of geological environmental characteristics suitable for the domestic geological environment. In this study, we evaluated the characteristics of hydraulic conductivity, which is considered the most important evaluation parameter in the field of hydrogeology, targeting a deep-depth rock aquifer where actual disposal facilities are expected to be located. In particular, for the first time in Korea, we obtained in-situ pressure-flow data by directly conducting hydraulic tests in boreholes at depths ranging from 500 m to 750 m in various rock types distributed in Korea (granite/volcanic rock/gneiss/mudstone). And we derived hydraulic conductivity values by rock types and depth using verified analytical methods. For this purpose, precision hydraulic testing equipment developed in-house through this study was used, and detailed investigation procedures based on standard test methods were applied to field tests. As a result of the analysis, the average hydraulic conductivity value was found to be in the range of 10-9 m/s in all granite/volcanic rock/gneiss areas. In the mudstone area, an average hydraulic conductivity value of 10-11 m/s was derived, which was about 100 times (2 orders of magnitude) lower than that of the fractured rock aquifers. Moreover, permeability tended to slightly decrease with depth in fractured rock aquifers (granite and volcanic rock areas) containing many rock fractures. The gneiss area tended to have large local differences in permeability according to the composition of the stratum and the development of fracture zones rather than depth. In mudstone areas with weak fracture development, there was no significant variation in rock permeability according to depth. The hydraulic conductivity results by various rock types and depth presented in this study are expected to be utilized in building a foundational database for the site selection, design, and construction of disposal facilities in Korea.

고준위방사성폐기물 심층처분 시, 부지선정을 성공적으로 진행하기 위해서는 단계별 접근법과 그에 따라 국내 지질환경에 적합한 지질환경특성 평가인자의 체계적인 선정 및 조사평가가 중요하다. 본 연구에서는 실제 처분시설이 위치할 것으로 예상되는 고심도의 암반대수층을 대상으로, 수리지질분야의 가장 핵심적인 평가인자로 고려되고 있는 수리전도도 특성을 평가하였다. 특히 국내에 분포하는 다양한 암종지역(화강암/화산암/편마암/이암)에서 각각 500 m 이하 750 m에 이르는 깊은 심도까지, 직접 시추공 내 수리시험을 수행하여 현지 압력-유량 자료를 획득하고, 검증된 해석방법을 통해 암종별/심도별 수리전도도 값을 도출한 일련의 수행 과정과 분석 결과들은 국내 최초의 종합적 고심도 수리특성 연구 시도라 할 수 있다. 이를 위해, 본 연구를 통해 자체적으로 개발된 정밀수리시험장비가 사용되었으며, 표준시험법을 바탕으로 한 상세조사절차가 현장시험에 적용되었다. 분석 결과, 화강암/화산암/편마암 지역에서 모두 평균 10-9 m/s 범위의 수리전도도 값이 나타났으며, 이암 지역에서는 이보다 100배(2 order)정도 낮은 수준인 평균 10-11 m/s 수리전도도 값이 도출되었다. 또한 암반절리가 다수 포함되어 있는 균열암반대수층인 화강암과 화산암 지역에서는 전체적으로 심도에 따라 투수성이 약간 감소하는 경향을 보였다. 편마암 지역은 심도보다는 지층의 암상과 그에 따른 파쇄대의 발달 여부에 따라 국부적으로 투수성 차이가 큰 경향을 나타냈다. 균열 발달이 미약한 이암 지역에서는 심도에 따른 암반 투수성의 변동이나 뚜렷한 경향성이 관찰되지 않았다. 본 연구에서 제시된 암종별/심도별 수리전도도 결과 자료들은 국내 처분부지 선정과 처분시설 설계 및 건설을 위한 기반 데이터베이스 구축에 활용될 것으로 기대된다.

Keywords

Acknowledgement

본 연구는 한국지질자원연구원의 기본사업인 "HLW 심층처분을 위한 지체구조별 암종 심부 특성 연구(과제코드 : GP2020-002, 과제번호: 24-3115)" 및 "심지층 개발과 활용을 위한 지하심부 특성평가 기술개발(과제코드 : GP2020-010, 과제번호: 24-3414)" 지원을 받아 수행되었습니다. 현장시험에 도움을 주신 (주)지오제니 컨설턴트와 (주)희송지오텍에 감사의 말씀드립니다.

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