Theoretical Equations on Hydraulic Conductivities of Bentonite-Based Buffer and Backfill for Underground Disposal of Radioactive Wastes
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 134, Issue 4
Abstract
Compacted bentonite and sand-bentonite mixtures are sought as buffer and backfill materials for high-level radioactive waste disposal facilities because they have very low permeability. To establish specifications such as the dry density and sand-bentonite mass ratio for buffer and backfill materials, we must quantitatively evaluate a material’s hydraulic conductivities. This study presents theoretical new equations for evaluating the hydraulic conductivity of compacted bentonites and sand-bentonite mixtures. New equations are proposed for evaluating the flow velocity of interlayer water between two montmorillonite parallel-plate layers considering the swelling behaviors of montmorillonite. Furthermore, a prediction method for hydraulic conductivity of compacted bentonite and sand-bentonite mixtures is presented by combining new equations with previous equations for evaluating swelling behavior of montmorillonite in bentonite. The applicability of this method is clarified by comparing predicted results with experimental data reported by previous research on hydraulic conductivities of compacted bentonites and sand-bentonite mixtures.
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Acknowledgments
This study was supported through funding by TEPCO Research Foundation. The writer also thanks Mr. Ogata, a former senior researcher of the Central Research Institute of Electric Power Industry, and Prof. Yasuhara, Dr. Murakami, and all of the members and students of the geotechnical laboratory at Ibaraki University for their kind assistance and discussions.
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Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 134 • Issue 4 • April 2008
Pages: 497 - 508
Copyright
© 2008 ASCE.
History
Received: Apr 10, 2006
Accepted: Aug 27, 2007
Published online: Apr 1, 2008
Published in print: Apr 2008
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