Journal
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
Volume 51, Issue -, Pages 64-75Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijrmms.2012.01.001
Keywords
Desiccation process; Desiccation cracks; Clay; Tournemire argillite; Digital image correlation; Hydro-mechanical behavior
Funding
- GNR TRASSE (Transfert des Radionucleides dans les Sols, les Sous-sols et vers les Ecosystemes) [PA-TRASSE-29]
- French Institute for Nuclear Safety and Radioprotection (IRSN)
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A set of samples taken from the Tournemire site was submitted to a desaturation process in an oven at different temperature levels of 40 degrees C; 50 degrees C, 80 degrees C, 105 degrees C, 150 degrees C and 200 degrees C. The resulting hydromechanical behavior was studied by measuring the strain fields obtained from a non-invasive method called Digital Image Correlation (DIC). After a few dozens of minutes from the beginning of the thermal loading, the induced strains concentrated into narrow zones or bands indicating strain localization. These narrow zones were precursors of desiccation cracks which were also detected from the first temperature level (at 40 degrees C or 50 degrees C). Our results confirmed the fundamental role of the textural and sedimentological heterogeneities in the cracking process. Desiccation cracks appeared at the interface between clay matrix and macroscopic non-clayey heterogeneity (i.e., calcite concretion) and were predominantly parallel to the bedding planes. At a temperature level of 105 degrees C, the desiccation cracks were no longer observable and seemed to close. This healing process was interpreted as a thermally driven process: when the shrinkage limit was reached, a thermal dilation of the water+clay minerals system occurred leading to a gradual closure of desiccation cracks. (C) 2012 Elsevier Ltd. All rights reserved.
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