터널과지하공간 (Tunnel and Underground Space)

  • 제29권1호
  • /
  • Pages.38-51
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  • 2019
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  • 1225-1275(pISSN)
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  • 2287-1748(eISSN)
한국암반공학회 (Korean Society for Rock Mechanics and Rock Engineering)
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불포화토의 열·탄소성 거동 분석을 위한 Barcelona Basic Model 소개

Introduction of Barcelona Basic Model for Analysis of the Thermo-Elasto-Plastic Behavior of Unsaturated Soils

  • 이창수 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 윤석 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 이재원 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 김건영 (한국원자력연구원 방사성폐기물처분연구부)
  • Lee, Changsoo (Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute) ;
  • Yoon, Seok (Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute) ;
  • Lee, Jaewon (Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute) ;
  • Kim, Geon Young (Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute)
  • 투고 : 2019.02.18
  • 심사 : 2019.02.25
  • 발행 : 2019.02.28
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초록

Barcelona Basic Model(BBM)은 응력의 변화에 따른 부피변화뿐만 아니라 흡입력의 변화에 따른 팽윤거동을 설명할 수 있으며, 흡입력 변화에 따른 점착력과 선행압밀응력의 변화와 온도변화에 따른 선행압밀응력의 변화를 고려할 수 있다. 따라서, 고준위방사성폐기물 처분시스템에서 공학적방벽재로 고려되고 있는 벤토나이트 완충재의 열-수리-역학적 복합거동을 예측 및 분석하는 것에 많이 활용되고 있다. 그러나 우리나라의 암반 및 지반 공학자들에게 잘 알려져 있지 않기 때문에 BBM을 소개하고자 한다. BBM은 불포화 토질의 역학적 거동을 모사하기 위해 Modified Cam Clay(MCC) 모델을 확장하여 만들어 졌기 때문에 본 고에서는 먼저 MCC 모델을 간략하게 소개하고, 열-탄소성 모델인 BBM을 상세히 소개하였다.

Barcelona Basic Model (BBM) can describe not only swelling owing to decrease in effective stress, but also wetting-induced swelling due to decrease in suction. And the BBM can also consider increase in cohesion and apparent preconsolidation stress with suction, and decrease in the apparent preconsolidation stress with temperature. Therefore, the BBM is widely used all over the world to predict and to analyze coupled thermo-hydro-mechanical behavior of bentonite which is considered as buffer materials at the engineered barrier system in the high-level radioactive waste disposal system. However, the BBM is not well known in Korea, so this paper introduce the BBM to Korean rock engineers and geotechnical engineers. In this study, Modified Cam Clay (MCC) model is introduced before all, because the BBM was first developed as an extension of the MCC model to unsaturated soil conditions. Then, the thermo-elasto-plastic version of the BBM is described in detail.

키워드

OBGHBQ_2019_v29n1_38_f0001.png 이미지

Fig. 1. Principles of final disposal of spent nuclear fuel according to the KBS-3V method (SKB, 2010)

OBGHBQ_2019_v29n1_38_f0002.png 이미지

Fig. 2. Scheme of the coupled thermo-hydro-mechanical processes in the near field (modified after Salas et al. (2014))

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Fig. 3. Effect of dry density on thermal and hydraulic properties of bentonite

OBGHBQ_2019_v29n1_38_f0004.png 이미지

Fig. 4. Yield surface in the p' -q plane

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Fig. 5. Normal consolidation line and unloading-reloading (swelling) lines for an isotropic compression test

OBGHBQ_2019_v29n1_38_f0006.png 이미지

Fig. 6. An incremental consolidation pressure change due to movement of point from A' to A''

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Fig. 7. Relationship between preconsolidation stresses P0 and $p^*_0$ (Alonso et al., 1990)

OBGHBQ_2019_v29n1_38_f0008.png 이미지

Fig. 8. The yield surface in Barcelona Basic Model (modified after Gens, 1995)

OBGHBQ_2019_v29n1_38_f0009.png 이미지

Fig. 8. The yield surface in Barcelona Basic Model (modified after Gens, 1995) (Continued)

OBGHBQ_2019_v29n1_38_f0010.png 이미지

Fig. 9. Three-dimensional representation of the yield surface in the p'-q-T space (modified after Hueckel and Baldi (1990))

참고문헌

  1. Alonso, E.E., Gens, A. and A. Josa, 1990, A constitutive model for partially saturated soils." Geotechnique, Vol. 40, 405-430. https://doi.org/10.1680/geot.1990.40.3.405
  2. Akesson, M., Borgesson, L. and O. Kristensson, 2010, SR-Site Data report: THM modelling of buffer, backfill and other system components, SKB TR-10-44, Svensk Karnbranslehantering AB.
  3. CIEMAT, 2002, Code_Bright User's Guide, Part V1d Thermo-Elasto-Plastic Constitutive Model, Departamento de Ingenieria del Terreno, Universidad Politecnica de Cataluna, Barcelona, Spain.
  4. ENRESA, 2000, FEBEX project, Full-scale engineered barriers experiment for a deep geological repository for high level radioactive waste in crystalline host rock, Final report, ENRESA, Madrid.
  5. Gaus, I., Garitte B., Senger R., Gens A., Vasconcelos R., Garcia-Sineriz J.-L., Trick T., Wieczorek K., Czaikowski O., Schuster K., Mayor J.C., Velasco M., Kuhlmann U. and M.V. Villar, 2014, The HE-E Experiment: Lay-out, Interpretation and THM Modelling, PEBS Deliverable D3.2-1. NAB 14-53. Nagra, Wettingen.
  6. Gens, A., 1995, Constitutive laws. In: Gens, A., Jouanna, P., Schrefler, B.A. (Eds.), Modern Issues in Non-saturated Soils, Springer-Verlag, New York, 129-158.
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