Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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Benchmark Numerical Simulation on the Coupled Behavior of the Ground around a Point Heat Source Using the TOUGH-FLAC Approach

TOUGH-FLAC 기법을 이용한 점열원 주변지반의 복합거동에 대한 벤치마크 수치모사

  • Dohyun Park (Deep Subsurface Storage and Disposal Research Center, Korea Institute of Geoscience and Mineral Resources)
  • 박도현 (한국지질자원연구원 심층처분환경연구센터)
  • Received : 2024.04.12
  • Accepted : 2024.04.19
  • Published : 2024.04.30
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Abstract

The robustness of a numerical method means that its computational performance is maintained under various modeling conditions. New numerical methods or codes need to be assessed for robustness through benchmark testing. The TOUGH-FLAC modeling approach has been applied to various fields such as subsurface carbon dioxide storage, geological disposal of spent nuclear fuel, and geothermal development both domestically and internationally, and the modeling validity has been examined by comparing the results with experimental measurements and other numerical codes. In the present study, a benchmark test of the TOUGH-FLAC approach was performed based on a coupled thermal-hydro-mechanical behavior problem with an analytical solution. The analytical solution is related to the temperature, pore water pressure, and mechanical behavior of a fully saturated porous medium that is subjected to a point heat source. The robustness of the TOUGH-FLAC approach was evaluated by comparing the analytical solution with the results of numerical simulation. Additionally, the effects of thermal-hydro-mechanical coupling terms, fluid phase change, and timestep on the computation of coupled behavior were investigated.

수치해석 기법의 강건성은 다양한 모델링 조건에서 계산 성능이 유지되는 것을 의미하며, 새로운 해석기법 또는 수치코드는 벤치마크 테스트를 통해 강건성이 평가될 필요가 있다. TOUGH-FLAC 모델링 기법은 국내외적으로 이산화탄소 지중저장, 사용후핵연료 지층처분, 지열 개발 등 다양한 분야에 적용되었으며, 실험 계측자료, 다른 수치코드들과의 결과 비교를 통해 모델링 유효성이 분석되었다. 본 연구에서는 해석해를 갖는 열-수리-역학적 복합거동 문제를 토대로 TOUGH-FLAC 기법의 벤치마크 테스트를 수행하였다. 적용된 해석해는 완전히 포화된 지반에 점열원 작용 시 주변매질의 온도, 간극수압, 역학적 거동과 관계되며, 해석해와 수치모사 결과를 비교하여 TOUGH-FLAC 기법의 강건성이 평가되었다. 또한, 열-수리-역학 해석의 연계항, 유체 상변화, 시간증분이 복합거동 계산에 미치는 영향을 조사하였다.

Keywords

Acknowledgement

본 연구는 한국지질자원연구원의 기본사업인 '심지층 개발과 활용을 위한 지하심부 특성평가 기술개발(과제코드 GP2020-010)'의 일환으로 수행되었습니다.

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