Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT) (방사성폐기물학회지)

Korean Radioactive Waste Society (한국방사성폐기물학회)
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A Review on Measurement Techniques and Constitutive Models of Suction in Unsaturated Bentonite Buffer

불포화 벤토나이트 완충재의 수분흡입력 측정기술 및 구성모델 고찰

  • Received : 2019.08.13
  • Accepted : 2019.09.16
  • Published : 2019.09.30
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Abstract

Suction of unsaturated bentonite buffers is a very important input parameter for hydro-mechanical performance assessment and design of an engineered barrier system. This study analyzed suction measurement techniques and constitutive models of unsaturated porous media reported in the literature, and suggested suction measurement techniques and constitutive models suitable for bentonite buffer in an HLW repository. The literature review showed the suction of bentonite buffer to be much higher than that of soil, as measured by total suction including matric suction and osmotic suction. The measurement methods (RH-Cell, RH-Cell/Sensor) using a relative humidity sensor were suitable for suction measurement of the bentonite buffer; the RH-Cell /Sensor method was more preferred in consideration of the temperature change due to radioactive decay heat and measurement time. Various water retention models of bentonite buffers have been proposed through experiments, but the van Genuchten model is mainly used as a constitutive model of hydro-mechanical performance assessment of unsaturated buffers. The water characteristic curve of bentonite buffers showed different tendencies according to bentonite type, dry density, temperature, salinity, sample state and hysteresis. Selection of water retention models and determination of model input parameters should consider the effects of these controlling factors so as to improve overall reliability.

불포화 벤토나이트 완충재의 수분흡입력은 공학적방벽의 수리-역학적 성능평가 및 설계에 있어 매우 중요한 입력인자이다. 본 연구에서는 문헌에 보고된 불포화 다공성매질의 수분흡입력 측정기술과 구성모델을 분석하고, 고준위폐기물처분장의 벤토나이트 완충재에 적합한 수분흡입력 측정기술과 구성모델을 제안하였다. 문헌 분석결과, 벤토나이트 완충재의 수분흡입력은 일반토질보다 훨씬 높은 값을 가지며, 매트릭수분흡입력과 삼투흡입력을 포함하는 총수분흡입력을 측정하여 사용하였다. 벤토나이트 완충재의 수분흡입력 측정에는 상대습도센서를 이용한 측정방법(RH-Cell, RH-Cell/Sensor)이 적합하였으며, 핵종 붕괴열에 의한 온도변화와 측정 소요시간을 고려했을 때에는 RH-Cell/Sensor 방법이 더 선호되었다. 벤토나이트 완충재의 수분보유모델은 실험을 통해 여러 가지 모델이 제안되었지만, 불포화 완충재의 수리-역학적 성능평가 구성모델로는 대부분 van Genuchten모델이 사용되었다. 벤토나이트 완충재의 수분특성곡선은 벤토나이트의 종류, 건조밀도, 온도, 염도, 측정 시 시료상태와 이력과정에 따라 서로 다른 경향을 보였다. 수분보유모델의 선정 및 모델인자 결정에는 신뢰도 향상을 위해 이러한 인자들의 영향이 고려되어야 한다.

Keywords

References

  1. OECD/NEA, "Timing of high level waste disposal", NEA No. 6244, OECD (2008).
  2. Svensk Kambranslehantering AB (SKB). Design and Production of the KBS-3 Repository, SKB TR-10-12 (2010).
  3. M.V. Villar, "Thermo-hydro-mechanical characterization of a bentonite from Cabo de Gata: A Study applied to the use of bentonite as sealing materials in high level radioactive waste repositories", ENRESA Publication Technica, 04/2002 (2002).
  4. M.V. Villar, "MX-80 bentonite. Thermo-hydro-mechanical characterization performed at CIEMAT in the context of the prototype project", CIEMAT/DIAE/54540/2/04 (2004).
  5. J.O. Lee, W.J. Cho, and S. Kwon, "Suction and water uptake in unsaturated compacted bentonite", Ann. Nucl. Energy, 38, 520-526 (2011). https://doi.org/10.1016/j.anucene.2010.09.016
  6. S. Yoon, J.S. Jeon, C. Lee, W.J. Cho, S.R. Lee, and G.Y. Kim, "Evaluation of soil-water characteristic curve for domestic bentonite buffer", J. Nucl. Fuel Cycle Waste Technol., 17(1), 29-36 (2019). https://doi.org/10.7733/jnfcwt.2019.17.1.29
  7. I.S. McQueen and R.F. Miller, "Approximating soil moisture characteristics from limited data: Empirical evidence and tentative model", Water Resour. Res., 10(3), 521-527 (1974). https://doi.org/10.1029/WR010i003p00521
  8. P. Hu, Q. Yang, and P. Li, "Direct and indirect measurement of soil suction in the laboratory", Electronic J. Geotech. Eng., 15, 1-14 (2010).
  9. M.V. Villar, "Thermo-hydro-mechanical characterization of a bentonite from Cabo de Gata: A Study applied to the use of bentonite as sealing materials in high level radioactive waste repositories", ENRESA Publication Technica, o4/2002 (2002).
  10. J.I. Gmitro and T. Vermeulen, "Vapor-liquid equilibria for aqueous sulfuric acid", An. I. Ch. E. J., 10(5), 740 (1964).
  11. M.V. Villar, "MX-80 bentonite. Thermo-hydro-mechanical characterization performed at CIEMAT in the context of the prototype project", CIEMAT/DIAE/54540/2/04 (2004).
  12. J.O. Lee, W.J. Cho, and S. Kwon, "Suction and water uptake in unsaturated compacted bentonite", Ann. Nucl. Energy, 38, 520-526 (2011). https://doi.org/10.1016/j.anucene.2010.09.016
  13. M. van Genuchten, "A closed-form equation for predicting the hydraulic conductivity of unsaturated soils", Soil Sci. Soc. Am. J., 44, 892-898 (1980). https://doi.org/10.2136/sssaj1980.03615995004400050002x
  14. D. G. Fredlund and A. Xing, "Equations for the soil-water characteristic curve", Can. Geotech. J., 31, 521-532 (1994). https://doi.org/10.1139/t94-061
  15. I. Engelhardt, "Inverse modeling of gas, water and heat flow in bentonite/crushed rock backfill", Proc. TOUGH Sypm. 2003, LBNL, Berkeley, USA (2003).
  16. J.O. Lee, H. Choi, and G.Y. Kim, "Numerical simulation studies on predicting the peak temperature in the buffer of an HLW repository", Int. J. Heat and Mass Transfer, 115, 192-204 (2017). https://doi.org/10.1016/j.ijheatmasstransfer.2017.07.039
  17. W.J. Cho and S. Kwon, "Effects of variable saturation on the thermal analysis of the engineered barrier system for a nuclear water repository", Nucl. Technol., 177, 245-256 (2012). https://doi.org/10.13182/NT12-A13369
  18. M. Chijimatsu, Fujita, A. Kobayashi, and M. Nakano, "Experiment and validation of numerical simulation of coupled thermal, hydraulic and mechanical behaviour in the engineered buffer materials", Int. J. Numer. Anal. Meth. Geomech, 24, 403-424 (2000). https://doi.org/10.1002/(SICI)1096-9853(20000410)24:4<403::AID-NAG73>3.0.CO;2-E
  19. M. Wan, W.M. Ye, Y.G. Chen, Y.J. Cui, and J. Wang, "Influence of temperature on the water retention properties of compacted GMZ01 bentonite", Environ. Earth Sci., 73, 4053-4061 (2015). https://doi.org/10.1007/s12665-014-3690-y
  20. A. Seiphoori, A. Ferrari, and L. Laloui, "Water retention behaviour and microstructural evolution of MX-80 bentonite during wetting and drying cycles", Geotechnique, 64(9), 721-734 (2014). https://doi.org/10.1680/geot.14.P.017
  21. M.V. Villar, and A. Lloret, "Influence of temperature on the hydro-mechanical behaviour of a compacted bentonite", Appl. Clay Sci., 26, 337-350 (2004). https://doi.org/10.1016/j.clay.2003.12.026
  22. A. Lloret, M.V. Villar, M. Sanchez, A. Gens, X. Pintado, and E.E. Alonso, "Mechanical behaviour of heavily compactedbentonite under high suction changes", Geotechnique, 53(1), 27-40(2003). https://doi.org/10.1680/geot.2003.53.1.27
  23. A. Lloret, M.V. Villar, and E. Romero, "Final report on thermo-hydro-mechanical laboratory tests", FEBEX report 70-UPC-L-7-13., 158, Barcelona (2004).
  24. T. Kanno, T. Fugita, S. Takeuchi, H. Ishikawa, K. Hara, and M. Nakano, "Coupled Thermo-hydro-mechanical modelling of bentonite buffer material", Int. J. Numer. Anal. Meth. Geomech., 23, 1281-1307 (1999). https://doi.org/10.1002/(SICI)1096-9853(199910)23:12<1281::AID-NAG32>3.0.CO;2-I
  25. M. Chijimatsu, T. Fujita, Y. Sugita, and W. Taniguchi, "Evaluation of Coupled Thermo-Hydro-Mechanical Phenomena in the Near Field for Geological Disposal of High-Level Radioactive Waste", JNC TN8400 2000 - 008, Japan (2000).
  26. T. Nishimura and J. Koseki, "Changing of properties of unsaturated compacted bentonite due to hydration effort", J. Environ. Sci. Eng., B7, 92-102 (2018).
  27. B. Chen, L. Qian, W.M. Ye, Y.J. Cui, and J. Wang, "Soil-water characteristic curves of Gaomiaozi bentonite", Chinease J. Rock Mech. Eng., 25(4), 788-793 (2006).
  28. W.M. Ye, Q. Wang, Y.G. Chen, and B. Chen, "Advances on buffer/backfill properties of heavily compacted Gaomiaozi bentonite", Proc. of Int. Symp. on Geoenviron. Eng., ISGE2009, 8-10, Hangzhou, China (2009).
  29. W.M. Ye, J. Zhu, B. Chen, Y. Chen, and Y. Cui, "Experimental investigation on soil-water retention properties of compacted GMZ01 bentonite with consideration of temperature and initial dry density", 10th Asian Regional Conference of IAEG (2015).
  30. W. Sun, D. Sun, L. Fang, and S. Liu, "Soil-water characteristics of Gaomiaozi bentonite by vapor equilibrium technique", J. Rock Mech. Geotech. Eng. 6, 48-54 (2014). https://doi.org/10.1016/j.jrmge.2013.12.004
  31. H.J. Choi, J.Y. Lee, D.K. Cho, S.K. Kim, S.S. Kim, K.Y. Kim, J.T. Chung, M.S. Lee, J.W. Choi, and J.O. Lee. Korean Reference HLW disposal system, Korea Atomic Energy Research Institute, KAERI/TR-3563/2008 (2008).