[en] Bentonite-based materials are studied as potential barriers for the geological disposal of radioactive waste. In this context, the hydro-mechanical behaviour of the engineered barrier is first characterized by free swelling conditions followed by constant volume conditions. This paper presents an experimental study conducted in order to characterize the water retention behaviour of a compacted MX-80 bentonite/sand mixture. Then, based on observations of the material double structure and the water retention mechanisms in compacted bentonites, a new water retention model is proposed. The model considers adsorbed water in the microstructure and capillary water in the aggregate-porosity. The model is calibrated and validated against the experimental data. It is used for better understanding competing effects between volume change and water uptake observed during hydration under free swelling conditions.
P. Delage, M. Howat, Y.J. Cui. The relationship between suction and swelling properties in a heavily compacted unsaturated clay. Engineering Geology 50, 31-48 (1998)
A. Dueck. Laboratory results from hydro-mechanical tests on a water unsaturated bentonite. Engineering Geology 97 (1-2), 15-24 (2008)
M. Ajdari, G. Habibagahi, F. Masrouri. The role of suction and degree of saturation on the hydro-mechanical response of a dual porosity silt-bentonite mixture. Applied Clay Science 83-84, 83-90 (2013)
C. Gatabin, J. Talandier, F. Collin, R. Charlier, A.C. Dieudonné. Competing effects of volume change and water uptake on the water retention behaviour of a compacted MX-80 bentonite/sand mixture. Applied Clay Science 121-122, 57-62 (2016)
A.M. Tang, Y.J. Cui, T.T. Le. A study on the thermal conductivity of compacted bentonites. Applied Clay Science 41(3-4), 181-189 (2008)
E. Romero, A. Gens, A. Lloret. Water permeability water retention and microstructure of unsaturated compacted Boom Clay. Engineering Geology 54, 117-127 (1999)
C. Loiseau, Y.J. Cui, P. Delage. The gradient effect on the water flow through a compacted swelling soil. In: J.F.T. Juca, T.M.P. de Campos, F.A.M. Marinho (Eds), Unsaturated Soils, Proceedings of the 3rd International Conference on Unsaturated Soils (UNSAT2002), Recife, Brazil, 395-400 (2002)
M.V. Villar. Water retention of two natural compacted bentonites. Clays and Clay Minerals 55(3), 311-322 (2007)
E. Romero, G. Della Vecchia, C. Jommi. An insight into the water retention properties of compacted clayey soils. Géotechnique 61(4), 313-328 (2011)
S.S. Agus, Y.F. Arifin, S. Tripathy, T. Schanz. Swelling pressure - suction relationship of heavily compacted bentonite-sand mixtures. Acta Geotechnica 8(2), 155-165 (2013)
A. Seiphoori, A. Ferrari, L. Laloui. Water retention behaviour and microstructural evolution of MX-80 bentonite during wetting and drying cycles. Géotechnique 64(9), 717-734 (2014)
G. Della Vecchia, A.C. Dieudonne, C. Jommi, R. Charlier. Accounting for evolving pore size distribution in water retention models for compacted clays. International Journal of Numerical and Analytical Methods in Geomechanics 39(7), 702-723 (2015)
M.T. Van Genuchten. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal 44(5), 892-898 (1980)
R.H. Brooks, A.T. Corey. Hydraulic properties of porous media. Hydrological papers (Colorado State University) 3 (1964)
D.A. Sun, D. Sheng, L. Xiang, S.W. Sloan. Elastoplastic prediction of hydro-mechanical behaviour of unsaturated soils under undrained conditions. Computers and Geotechnics 35(6), 845-852 (2008)
D. Masin. Predicting the dependency of a degree of saturation on void ratio and sucion using effective stress principle for unsaturated soils. International Journal for Numerical and Analytical Methods in Geomechanics 34, 73-90 (2010)
S. Salager, M. Nuth, A. Ferrari, L. Laloui. Investigation into water retention behaviour of deformable soils. Canadian Geotechnical Journal 50, 200-208 (2013)
D. Gallipoli, A.W. Bruno, F. D'Onza, C. Mancuso. A bounding surface hysteretic water retention model for deformable soils. Géotechnique 65(10), 793-804 (2015)
M.M. Dubinin, L.V. Radushkevich. Equation of the characteristic curve of activated charcoal. Proceedings of the academy of Sciences, Physical Chemistry Section, USSR 55, 331-333 (1947)
A.C. Dieudonne, S. Levasseur, R. Charlier, G. Della Vecchia, C. Jommi. A water retention model for compacted clayey soils. In: S Pietruszcak, G.N. Pande (Eds.) Computational Geomechanics COMGEO III, Proceeding of the 3rd International Symposium on Computational Geomechanics, 23-31 (2013)
Q. Wang, A.M. Tang, Y.J. Cui, P. Delage, J.D. Barnichon, W.M. Ye. The effects of technological voids on the hydromechanical behaviour of DOI: 10.1051/9, compacted bentonite-sand mixture. Soils and Foundations 53(2), 232-245 (2013)
S. Saba, P. Delage, N. Lenoir, Y.J. Cui, A.M. Tang, J.D. Barnichon. Further insight into the microstructure of compacted bentonite-sand mixture. Engineering Geology 168, 141-148 (2014)
