Investigation of the behaviour of bentonite by mans of suction-controlled oedometer tests

摘要

In the context of an investigation of the near-fieldas a repository of high-level radioactive waste, the FEBEXProject, a set of laboratory tests has been designed to give a betterunder standing of the thermo-hydro-mechanical behaviour ofunsaturated, expansive clays and to achieve an experimentalcorroboration of the constitutive models for these clays. Amongthese tests, several suction-controlled oedometer tests have beenperformed on a compacted, highly-expansive slay. Seven of them,in which combined paths of loading, wetting and drying havebeen followed, are presented in this paper. Suctions employedrange from 0 to 500 MPa, and vertical loads from 0.1 to 9 MPa.The point of air entry has been identified for suctions around 120MPa, beyond which the sample becomes very stiff. The influenceof the stress path on the subsequent reversibility of thedeformations has been highlighted. The swelling properties seemto be kept after intense drying. The behaviour observed, includingcollapse, agrees with models that relate the effects of thedeformations in the microstructural level to those in the macrostructure.