Investigation of the damage induced by desiccation and heating of Tournemire argillite using digital image correlation
Investigation of the damage induced by desiccation and heating of Tournemire argillite using digital image correlation
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DOI：
10.1016/j.ijrmms.2012.01.001
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发表时间：
2012-04
影响因子：
7.2
通讯作者：
S. Hedan;P. Cosenza;V. Valle;Patrick Dudoignon;A. Fauchille;J. Cabrera
中科院分区：
文献类型：
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作者：
S. Hedan;P. Cosenza;V. Valle;Patrick Dudoignon;A. Fauchille;J. Cabrera
从 Tournemire 现场采集的一组样品在 40°C 不同温度水平的烘箱中进行去饱和过程； 50°C、80°C、105°C、150°C 和 200°C。通过测量通过称为“数字图像相关”（DIC）的非侵入性方法获得的应变场来研究由此产生的流体力学行为。从热加载开始几十分钟后，引起的应变集中到狭窄的区域或带中，表明应变局部化。这些狭窄区域是干燥裂纹的前兆，也是从第一温度水平（40°C 或 50°C）检测到的。我们的结果证实了结构和沉积学非均质性在裂解过程中的基本作用。干燥裂纹出现在粘土基质和宏观非粘土异质性（即方解石结核）之间的界面处，并且主要平行于层理面。在 105°C 的温度水平下，干燥裂纹不再可见并且似乎闭合。这种愈合过程被解释为热驱动过程：当达到收缩极限时，水+粘土矿物系统发生热膨胀，导致干燥裂缝逐渐闭合。
A set of samples taken from the Tournemire site was submitted to a desaturation process in an oven at different temperature levels of 40°C; 50°C, 80°C, 105°C, 150°C and 200°C. The resulting hydro-mechanical 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°C or 50°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°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.