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2025 Vol.35, Issue 5 Preview Page

Original Article

Assessment of Thermal, Hydraulic, and Mechanical Interaction Characteristics in a Multi Barrier System based on Backfill Material Designs

뒤채움재 설계안에 따른 다중방벽시스템의 열-수리-역학적 상호작용 특성 평가

Kwang-Il Kim1*
,
Yohan Cha1
,
Jinwoo Kim2
,
Changsoo Lee3
,
Jin-Seop Kim3
김 광일1*
,
차 요한1
,
김 진우2
,
이 창수3
,
김 진섭3
1Senior Researcher, Korea Atomic Energy Research Institute
2Postdoctoral Researcher, Korea Atomic Energy Research Institute
3Principal Researcher, Korea Atomic Energy Research Institute
1한국원자력연구원 선임연구원
2한국원자력연구원 박사후연수생
3한국원자력연구원 책임연구원
*Corresponding Author
31 October 2025. pp. 554-573
PDF XML Citation
Abstract

This study investigates the effects of three backfill material designs with varying bentonite- silica sand mix ratios on the thermal, hydraulic, and mechanical interactions in the multi- barrier system of the Improved Korean reference disposal system (KRS+). Numerical modeling results reveal that while the backfill material designs have minor effect on the temperature evolution within the repository, the saturation evolution shows notable differences based on the backfill properties. Specifically, increasing the bentonite content in the backfill accelerates backfill saturation, yet delays buffer saturation. The capability of the backfill to restrain upward movement of the buffer is enhanced by higher swelling pressure and stiffness of the backfill. However, stiffness increases tend to be more effective than additional swelling pressure for restaining upward movement of the buffer. Consequently, Designing an optimal mix ratio is crucial to ensure sufficient swelling pressure, fullfill performance criteria, and maintain relatively high stiffness. The backfill swelling pressure can act as a confining stress on the excavation surfaces, thereby enforcing the rock mass strength and reducing the extent of failure in the near-field rock mass, as the bentonite content in the backfill increases.

Keywords
High-level radioactive waste disposal
Coupled thermo-hydro-mechanical behavior
Numerical modeling
Backfill design
Improved Korean reference disposal system

본 연구에서는 벤토나이트/규사 혼합비가 다른 세 가지 뒤채움재의 설계안이 한국형 기준 처분시스템(KRS+) 내 다중방벽시스템의 열-수리-역학적 상호작용에 미치는 영향을 평가하였다. 수치모델링 결과, 처분시스템의 온도 변화는 뒤채움재 설계안에 거의 영향을 받지 않았으나, 포화도 변화는 뒤채움재의 물성에 따라 유의미한 차이를 보였다. 벤토나이트 혼합비가 증가할수록 뒤채움재 자체의 포화는 빨라졌으나 완충재의 포화는 다소 지연되는 경향을 나타냈다. 완충재 융기 제어 성능은 뒤채움재의 팽윤압과 강성이 증가할수록 우수해지는 결과가 도출되었다. 다만, 팽윤압 증가보다 강성의 증가가 완충재 융기 제어에 더 효과적인 것으로 나타나, 뒤채움재 설계 시 성능 기준을 충족시키는 팽윤압을 유지하면서도 상대적으로 높은 강성을 갖도록 적절한 혼합비를 산정할 필요가 있다. 뒤채움재의 팽윤압은 굴착면에 가해지는 구속압과 이에 따른 암반의 강도를 증가시켜 뒤채움재 내 벤토나이트 혼합비가 증가할수록 근계 암반의 파괴 영역이 감소하는 것으로 나타났다.

키워드
고준위방사성폐기물 처분
열-수리-역학적 상호작용
수치모델링
뒤채움재 설계안
한국형 기준 처분시스템
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Information
  • Publisher :Korean Society for Rock Mechanics and Rock Engineering
  • Publisher(Ko) :한국암반공학회
  • Journal Title :Tunnel and Underground Space
  • Journal Title(Ko) :터널과 지하공간
  • Volume : 35
  • No :5
  • Pages :554-573
  • Received Date : 2025-08-06
  • Revised Date : 2025-08-27
  • Accepted Date : 2025-09-03
  • DOI :https://doi.org/10.7474/TUS.2025.35.5.554
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