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| 1 | Microstructure and anisotropic swelling behaviour of compacted bentonite/sand mixture显示文摘Pre-compacted elements(disks,torus) of bentonite/sand mixture are candidate materials for sealing plugs of radioactive waste disposal.Choice of this material is mainly based on its swelling capacity allowing all gaps in the system to be sealed,and on its low permeability.When emplaced in the gallery,these elements will start to absorb water from the host rock and swell.Thereby,a swelling pressure will develop in the radial direction against the host rock and in the axial direction against the support structure.In this work,the swelling pressure of a small scale compacted disk of bentonite and sand was experimentally studied in both radial and axial directions.Different swelling kinetics were identified for different dry densities and along different directions.As a rule,the swelling pressure starts increasing quickly,reaches a peak value,decreases a little and finally stabilises.FOr some dry densities,higher peaks were observed in the radial direction than in the axial direction.The presence of peaks is related to the microstructure change and to the collapse of macropores.In parallel to the mechanical tests,microstructure investigation at the sample scale was conducted using microfocus X-ray computed tomography(μCT).Image observation showed a denser structure in the centre and a looser one in the border,which was also confirmed by image analysis.This structure heterogeneity in the radial direction and the occurrence of macro-pores close to the radial boundary of the sample can explain the large peaks observed in the radial swelling pressure evolution.Another interesting result is the higher anisotropy found at lower bentonite dry densities,which was also analysed by means of μCT observation of a sample at low bentonite dry density after the end of test It was found that the macro-pores,especially those between sand grains,were not filled by swelled bentonite,which preserved the anisotropic microstructure caused by uniaxial compression due to the absence of microstructure collapse. | Simona Saba Jean-Dominique Barnichon Yu-Jun Cui Anh Minh Tang Pierre Delage | 2014 | Journal of Rock Mechanics and Geotechnical Engineering2014，6，2： | 8 |
| 2 | Vacancy posting, job separation and unemployment fluctuations显示文摘 | Regis Barnichon | 2011 | Journal of Economic Dynamics and Control2011，，3： | 1 |
| 3 | Coupled thermo-hydro-mechanical processes in the near field of a high-level radioactive waste repository in clay formations显示文摘 | C.F. Tsang J.D. Barnichon J. Birkholzer X.L. Li H.H. Liu X. Sillen | 2011 | International Journal of Rock Mechanics and Mining Sciences2011，，： | 1 |
| 4 | Accounting for anisotropic effects in the prediction of the hydro-mechanical response of a ventilated tunnel in an argillaceous rock显示文摘In order to investigate the hydro-mechanical (HM) and chemical perturbations induced in an argillaceous formation by forced ventilation during the operational period of a nuclear waste repository, a specific experiment has been performed in a tunnel, at Mont Terri Underground Research Laboratory (URL) in Switzerland. This experiment has been selected in the international project DECOVALEX for model validation and the numerical simulation of this ventilation experiment (VE) is the object of the present paper. Since the argillaceous rock exhibits anisotropic properties, particular attention is given to the evaluation of the effects of various anisotropic features on the predicted results. In situ measurements such as relative humidity (RH), global water mass extracted, pore water pressure, water content, and relative displacements are compared to predictions using both isotropic and anisotropic parameters. Water permeability anisotropy is shown to be the most influencing parameter by far, whereas in situ stress anisotropy has an effect only during the excavation phase. The anisotropy for mechanical parameterization has also some influence, in particular through HM couplings. These HM couplings have the potential to be very significant in terms of providing confidence in describing the experimental observation, and should be considered for further investigation. | Alain Millard Alex Bond Shigeo Nakama Chengyuan Zhang Jean-Dominique Barnichon Benoit Garitte | 2013 | Journal of Rock Mechanics and Geotechnical Engineering2013，5，2： | 1 |
| 5 | Contribution of the bounding surface plasticity to the simulation of gallery excavation in plastic clays显示文摘 | Barnichon J D | 2002 | Engineering Geology2002，64，2： | 1 |
| 6 | Permeability of macro-cracked argillite under confinement: gas and water testing显示文摘 | DAVY C A SKOCZYLAS F BARNICHON J D | 2007 | Physics and Chemistry of the Earth: Parts A/B/C2007，32，814： | 1 |
| 7 | Contribution of the bounding surface plasticity to the simulation of gallery excavation in plastic clays 显示文摘 | Barnichon J D | 2002 | Engineering Geology2002，64，23： | 1 |
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