Journal of Korean Tunnelling and Underground Space Association (한국터널지하공간학회 논문집)

Korean Tunnelling and Underground Space Association (한국터널지하공간학회)
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Evaluation of Mazars damage model of KURT granite under simulated coupled environment of geological disposal

처분 복합환경을 고려한 KURT 화강암의 Mazars 손상모델 평가

  • 김진섭 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 홍창호 (한국원자력연구원 방사성폐기물처분연구부) ;
  • 김건영 (한국원자력연구원 방사성폐기물처분연구부)
  • Received : 2020.06.09
  • Accepted : 2020.07.09
  • Published : 2020.07.31
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Abstract

In this study, the damage parameters of Mazars model for KURT (KAERI Underground Research Tunnel) granite are measured form uniaxial compressive and Brazilian tests under the simulated coupled condition of a deep geological disposal. The tests are conducted in three different temperatures (15℃, 45℃, and 75℃) and dry/saturated conditions. Major model parameters such as maximum effective tensile strain (𝜖d0), At, Bt, Ac, and Bc differ from the typical reference values of concrete specimens. This is likely due to the difference in elastic modulus between rock and concrete. It is found that the saturation of specimens causes an increase in value of Bt and Bc while, the rise in temperature increases 𝜖d0 and Bt and decreases Bc. The damage model obtained from this study will be used as the primary input parameters in the development of coupled Thermo-Hydro-Mechanical Damage numerical model in KAERI.

본 연구에서는 처분장의 장기 건전성 평가모델을 확보하기 위해 한국원자력연구원 내 지하처분연구시설의 화강암을 대상으로 심층 처분복합환경을 모사한 암석시편의 Mazars 손상모델 상수를 측정하였다. 이를 위하여 실제 처분장 특성을 고려한 3가지 온도(15℃, 45℃, 75℃)와 건조/포화 조건에서 일축압축강도 및 간접인장강도 실험을 수행하였다. 최대유효인장변형률, At, Bt, Ac, Bc 등 주요 파라미터들은 콘크리트 대상으로 연구된 참고문헌의 값들과 차이를 보였으며 이는 암석과 콘크리트 시료의 탄성계수 차이 때문으로 판단된다. 시험결과 시료의 포화로 인해 Bt와 Bc의 값은 증가하였다. 또한 온도증가로 인해 최대 유효인장변형률과 Bt는 증가하였고 Bc는 감소하는 것을 확인하였다. 본 연구를 통해 도출된 손상모델은 한국원자력연구원 내에서 현재 개발 중인 Coupled Thermo-Hydro-Mechanical Damage 수치해석의 손상모델로 이용될 계획이다.

Keywords

References

  1. De Falco, A., Mori, M., Sevieri, G. (2018), "Mazars' damage model for masonry structures: a case study of a church in Italy", Proceedings of the COMSOL Conference 2018, Lausanne, pp. 1-7.
  2. Gassmann, F. (1951), "Elastic waves through a packing of spheres", Geophysics, Vol. 16, No. 4, pp. 673-682. https://doi.org/10.1190/1.1437718
  3. Gerard, B., Piajaudier-Cabot, G., Laborderie, C. (1998), "Coupled diffusion-damage modelling and the implications on failure due to strain localization", International Journal of Solids and Structures, Vol. 35, No. 31-32, pp. 4107-4120. https://doi.org/10.1016/S0020-7683(97)00304-1
  4. Hamon, F. (2013), Model of damage of Mazars, Code_Aster, R7.01.08., pp. 1-16.
  5. IAEA (2003), The long term storage of radioactive waste: Safety and sustainability, A Position Paper of International Experts, IAEA-LTS/RW, IAEA, Vienna.
  6. Idiart, A., Lavina, M., Coene, E. (2019), Modelling of concrete degradation-Hydro-chemo-mechanical processes, SKB Report R-19-12, pp. 41.
  7. Jianhong, Y., Wu, F.Q., Sun, J.Z. (2009), "Estimation of the tensile elastic modulus using Brazilian disc by applying diametrically opposed concentrated loads", International Journal of Rock Mechanics and Mining Sciences, Vol. 46, No. 3, pp. 568-576. https://doi.org/10.1016/j.ijrmms.2008.08.004
  8. Jirasek, M. (2011), "Damage and smeared crack models", Numerical Modeling of Concrete Cracking, Springer, pp. 1-49.
  9. Kachanov, L.M. (1958), "Time of rupture process under creep conditions", Izvestiya Akademii Nauk SSSR Otdelenie Tekniches, No. 8, pp. 26-31.
  10. Kim, J.S. Cho, W.J., Park, S., Kim, G.Y., Baik, M.H. (2019a), "A review on the design requirement of temperature in high-level nuclear waste disposal system: based on bentonite buffer", Journal of Korean Tunnelling and Underground Space Association, Vol. 21, No. 5, pp. 587-609. https://doi.org/10.9711/KTAJ.2019.21.5.587
  11. Kim, J.S., Cho, W.J., Kim, G.Y. (2019b), "Hydrothermal analysis of a double-layered bentonite in two-layered repository using TOUGH2 code: High performance buffer", Proceedings of the KRS 2019 Fall Conference, Vol. 17, No. 2, Jeju, pp. 265-266.
  12. Kim, J.S., Cho, W.J., Lee, K.S., Choi, H.J., Cho, G.C. (2012), "Numerical simulation for variations of water saturation in bentonite buffer under the effect of a rock joint using the TOUGHT2 code", Journal of Korean Tunnelling and Underground Space Association, Vol. 14, No. 6, pp. 575-593. https://doi.org/10.9711/KTAJ.2012.14.6.575
  13. Kim, J.S., Kwon, S.K., Sanchez, M., Cho, G.C. (2011), "Geological storage of high level nuclear waste", KSCE Journal of Civil Engineering, Vol. 15, No. 4, pp. 721-737. https://doi.org/10.1007/s12205-011-0012-8
  14. Lee, J., Kim, I.Y., Bae, D.S., Lee, M., Lee, Y.M, and Choi, H.J. (2016), A safety case of the conceptual disposal system for pyro-processing high level waste based on the KURT site (AKRS-16): I. Design base & disposal facility, Korea Atomic Energy Research Institute Report, KAERI/TR-6727/2016.
  15. Mazars, J. (1986), "A description of micro- and macroscale damage of concrete structures", Engineering Fracture Mechanics, Vol. 25, No. 5-6, pp. 729-737. https://doi.org/10.1016/0013-7944(86)90036-6
  16. Mazars, J., Grange, S. (2017), "Simplified strategies based on damage mechanics for concrete under dynamic loading, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 375, No. 2085, pp. 20160170. https://doi.org/10.1098/rsta.2016.0170
  17. Mazars, J., Hamon, F., Grange, S. (2015), "A new 3D damage model for concrete under monotonic, cyclic and dynamic loadings", Materials and Structures, Vol. 48, pp. 3779-3793. https://doi.org/10.1617/s11527-014-0439-8
  18. McKinnon, M.A., Cunningham, M.E. (2003), Dry storage demonstration for high-burnup spent nuclear fuel-feasibility study, Pacific Northwest National Laboratory Report, PNNL-14390.
  19. McKinnon, M.A., DeLoach, V.A. (1993), Spent nuclear fuel storage - Performance tests and demonstrations, Pacific Northwest Laboratory Report, PNL-8451.
  20. Park, S.H., Kim, J.S., Kim, G.Y., Kwon, S. (2019), "Evaluation of mechanical properties of KURT granite under simulated coupled condition of a geological repository", Journal of Korean Tunnelling and Underground Space Association, Vol. 21, No. 4, pp. 501-518. https://doi.org/10.9711/KTAJ.2019.21.4.501
  21. Pituba, J.J.C., Lacerda, M.M.S. (2012), "Simplified damage models applied in the numerical analysis of reinforced concrete structures", IBRACON Structures and Materials Journal, Vol. 5, No. 1, pp. 26-37.
  22. Saouridis, C. (1988), Objective identification and numerical simulation of softening: multiple scale approach to the damage process of concrete, Ph.D. Thesis, Paris-6 University, LMT Cachan (in French).
  23. Souissi, S., Miled, K, Hamdi, E., Sellami, H. (2017), "Numerical modeling of rock damage during indentation process with reference to hard rock drilling", International Journal of Geomechanics, Vol. 17, No. 7, pp. 04017002. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000862
  24. Xu, S., White, R.E. (1995), "A new velocity model for clay-sand mixtures", Geophysical Prospecting, Vol. 43, No. 1, pp. 91-118. https://doi.org/10.1111/j.1365-2478.1995.tb00126.x