A numerical interpretation of density homogenization of bentonite material in wetting process

Atsushi Iizuka, Yusuke Takayama, Shinya Tachibana, Shintaro Ohno, Ichizo Kobayashi, Katsuyuki Kawai

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Due to its low permeability and excellent expansion characteristics, bentonite is an excellent candidate with potential use as a buffer in the disposal of nuclear waste. Its expansion characteristics, activated by wetting, can be interpreted based on the full saturation line, depicted as a unique line on the density and the confining pressure relationship as proposed by Kobayashi et al. (2007). In addition, its elasto-plastic constitutive relation can also be formulated by introducing additional irreversible strain component describing the expansion of the montmorillonite present in the bentonite material. A constitutive model can consistently express the mechanical behavior of the compacted bentonite material from the unsaturated to the fully saturated state. This paper describes the density homogenization process that was conducted through a series of soil-water coupled elasto-plastic finite element simulations. Specifically, bentonite specimens, with different initial densities, were permeated with a constant water head. Stresses and strains developing in bentonite, particularly the density change, were carefully examined. A series of numerical simulations, performed on the two specimens, showed that specimens did not homogenize to a unique value of density upon reaching the fully saturated state. To confirm the simulation results, we carried out a series of experiments. The experimental results also support our simulation results.

    Original languageEnglish
    Title of host publicationASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM 2011
    Pages949-954
    Number of pages6
    EditionPARTS A AND B
    DOIs
    Publication statusPublished - 2011
    EventASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM 2011 - Reims, France
    Duration: 2011 Sep 252011 Sep 29

    Publication series

    NameProceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM
    NumberPARTS A AND B

    Other

    OtherASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM 2011
    Country/TerritoryFrance
    CityReims
    Period11/9/2511/9/29

    Keywords

    • Bentonite
    • Swelling
    • Unsaturated compacted soils

    ASJC Scopus subject areas

    • Safety, Risk, Reliability and Quality
    • Energy Engineering and Power Technology
    • Waste Management and Disposal

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