TY - GEN
T1 - A numerical interpretation of density homogenization of bentonite material in wetting process
AU - Iizuka, Atsushi
AU - Takayama, Yusuke
AU - Tachibana, Shinya
AU - Ohno, Shintaro
AU - Kobayashi, Ichizo
AU - Kawai, Katsuyuki
PY - 2011
Y1 - 2011
N2 - 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.
AB - 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.
KW - Bentonite
KW - Swelling
KW - Unsaturated compacted soils
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U2 - 10.1115/ICEM2011-59153
DO - 10.1115/ICEM2011-59153
M3 - Conference contribution
AN - SCOPUS:84882977226
SN - 9780791854983
T3 - Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM
SP - 949
EP - 954
BT - ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM 2011
T2 - ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, ICEM 2011
Y2 - 25 September 2011 through 29 September 2011
ER -