한국산학기술학회논문지 (Journal of the Korea Academia-Industrial cooperation Society)

  • 제16권8호
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  • Pages.5654-5663
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  • 2015
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  • 1975-4701(pISSN)
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  • 2288-4688(eISSN)
한국산학기술학회 (The Korea Academia-Industrial cooperation Society)
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불포화토에 대한 반복삼축압축시험의 요소시뮬레이션을 위한 응력-변형율 관계의 수립

Inducing stress-strain relationship for element simulation of cyclic triaxial test on unsaturated soil

  • 이충원 (국민안전처 국가민방위재난안전교육원)
  • Lee, Chung-Won (National Civil Defense and Disaster Management Training Institute, Ministry of Public Safety and Security)
  • 투고 : 2015.05.04
  • 심사 : 2015.08.06
  • 발행 : 2015.08.31
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초록

부(-)의 간극수압으로서 불포화토 내에 작용하는 석션은 입자간 응력을 증가시키며, 이에 따라 토립자 골격의 항복응력 및 소성전단강성을 증대시키는 등, 불포화토의 역학적 특성에 지대한 영향을 미친다. 따라서, 본 연구에서는 이러한 석션의 효과를 지진 등의 동적 하중조건에서 고려하기 위하여 불포화토에 대해 확장된 반복탄소성구성식에 근거한 응력-변형율 관계를 제 1 항복함수 및 제 2 항복함수를 고려하여 유도하였다. 본 관계를 2차원 및 3차원 수치해석에서 액상화 이후의 압밀거동 예측 등에 적용하는 경우에는 평균골격응력(Mean skeleton stress)의 변화를 반영하는 제 2 항복함수의 도입이 필요하나, 요소시뮬레이션에서는 제 1 항복함수만으로도 수치해석을 위한 각 물성치 및 석션 파라미터 결정이 가능할 것으로 사료된다. 본 관계와 응력반전을 반영한 반복재하 루틴을 함께 코딩(Coding)할 경우 불포화조건 하에서의 반복삼축압축시험에 대한 수치해석적 모사가 가능할 것으로 보이며, 본 연구결과는 동적 하중이 작용하는 불포화토 거동 예측의 정확도 제고에 기여할 것으로 전망된다.

In the unsaturated soil, suction, the negative pore water pressure leads to increases of the yield stress and the plastic shear stiffness of the soil skeleton due to the growth in interparticle stress. Therefore, in this study, the stress-strain relationship based on cyclic elasto-plastic constitutive model extended for unsaturated soil considering the 1st and the 2nd yield functions was induced in order to account for these effects of suction under the dynamic loading condition such as the earthquake. Through the program code considering this relationship and the routine of the cyclic loading with the reversion of loading direction, the numerical simulation of the cyclic triaxial test under the unsaturated condition would be possible. It is expected that the results of this study possibly contribute to the accuracy improvement on the prediction of unsaturated soil behavior under the dynamic loading condition.

키워드

참고문헌

  1. F. Oka, A. Yashima, A. Tateishi, Y. Taguchi, S. Yamashita, "A cyclic elastoplastic constitutive model for sand considering a plastic-strain dependence of the shear modulus", Geotechnique, Vol. 49, No. 5, pp. 661-680, 1999. DOI: http://dx.doi.org/10.1680/geot.1999.49.5.661
  2. F. Oka, "A cyclic elasto-viscoplastic constitutive model for clay based on the non-linear hardening rule", Proc. 4th International Symposium on Numerical Models in Geomechanics, Swansea, Pande, G. N. and Pietruszczak, S. eds., 1, Balkema, pp. 105-114, 1992.
  3. Y. Taguchi, A. Tateishi, F. Oka and A. Yashima, "A Cyclic elasto-plastic model based on the generalized flow rule ant its application", Proc. 5th Int. Symposium on Numerical Models in Geomechanics, Davos, Switzerland, Pande, G. N. and Pietruszczak, S. eds., Balkema, pp. 57-62, 1995.
  4. A. Tateishi, Y. Taguchi, F. Oka and A. Yashima, "An elasto-plastic model for sand and its application under various stress conditions", Proc. of 1st Int. Conference on Earthquake Geotechnical Engineering, Tokyo, Ishihara, K. ed., Balkema, Vol. 1, pp. 399-404, 1995.
  5. F. Oka and H. Washizu, "Constitutive equations for sand and overconsolidated clays", Proc. Int. Conference on Recent Advances in Earthquake Engineering and Soil Dynamics, St. Louis, Prakash, S. ed., 1, pp. 71-74, 1981.
  6. P. J. Armstrong and C. O. Frederick, "A mathematical representation of the multiaxial Bauschinger effect", C. E. G. B. Report RD/B/N, p. 731, 1966.
  7. J. L. Chaboche and G. Rousselier, "On the plastic and viscoplastic constitutive equations Part I and Part II", Journal of Pressure Vessel Technology, Transactions of the ASME, Vol. 105, pp. 153-164, 1983. https://doi.org/10.1115/1.3264257
  8. F. Oka, "Constitutive equations for granular materials in cyclic loadings", Proc. IUTAM Conference on Deformation and Failure of Granular Materials, Delft, Vermeer, P. A. and Luger, H. J. eds., Balkema, pp. 297-306, 1982.
  9. P. M. Naghdi and J. A. Trapp, "Restrictions on constitutive equations of finitely deformed elasto-plastic materials", Quarterly Journal of Mechanics and Applied Mathematics, Vol. 28, Pt. 1, pp. 25-46, 1975. DOI: http://dx.doi.org/10.1093/qjmam/28.1.25
  10. F. Oka, T. Kodaka, S. Kimoto, Y. S. Kim and N. Yamasaki, "A multi-phase coupled FE analysis using an elasto-viscoplastic model for unsaturated soil", Geomechanics II, Geotechnical Special Publication, ASCE, Proc. 2nd US-Japan workshop on Geomechanics, pp. 124-131, 2006. DOI: http://dx.doi.org/10.1061/40870(216)10
  11. D. Gallipoli, A. Gens, R. Sharma and J. Baunat, "An elasto-plastic model for unsaturated soil incorporating the effects of suction and degree of saturation on mechanical behavior", Geotechnique, Vol. 53, No. 1, pp. 123-135, 2003. DOI: http://dx.doi.org/10.1680/geot.2003.53.1.123
  12. C. Jommi, "Remarks on the constitutive modelling of unsaturated soils, Experimental Evidence and Theoretical Approaches in Unsaturated Soils", Tarantino, A. and Mancuso, C. eds., Balkema, pp. 139-153, 2000.
  13. F. Oka, T. Kodaka, S. Kimoto, R. Kato and S. Sunami, "A hydro-mechanical coupled analysis of an unsaturated river embankment due to seepage flow", Key engineering materials, Trans tech publications, Vol. 340-341, pp. 1223-1230, 2007. DOI: http://dx.doi.org/10.4028/www.scientific.net/KEM. 340-341.1223
  14. F. Oka, S. Kimoto, R. Kato, S. Sunami and T. Kodaka, "A soil-water coupled analysis of the deformation of an unsaturated river embankment due to seepage flow and overflow", Proc. 12th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG), Goa, India, 1-6 October 2008, Singh, D. N. ed., pp. 2029-2041, 2008.
  15. R. Kato, "Development of an unsaturated seepagedeformation coupled simulation method and its application to river embankment", Ph.D. dissertation, Kyoto University, Japan, 2011. (in Japanese)