Microscopic Investigation of the Deformation Mechanisms of Argillaceous Rock

Argillaceous rock is encountered in a variety of engineering circumstances such as civil engineering and petroleum engineering; a good understanding of the hydromechanical behavior of the involved rock is of crucial importance. However, characterization of this rock is challenging: it exhibits complex coupled thermo-hydro-chemo-mechanical behavior and a multi-heterogeneity, the description of which would strongly benefit from an improved experimental insight on their deformation and damage mechanisms at micro-scale. We propose here an experimental method for micro-scale characterization, consisting of in situ tests within the chamber of an environmental scanning electron microscope (ESEM), and quantification at micrometric scale of the induced local strains through analyzing high resolution imaging by digital image correlation techniques (DIC). On the basis of this method, the hydromechanical behavior of argillaceous rock can be investigated at their inclusion-matrix-composite microstructure: this scale is of particular interest because the complex matrix-inclusion interactions are a key mechanisms governing the deformation and damage of such rocks. We present some recent observations of the evolution of argillaceous rock subject to mechanical load, in particular the key role of the microstructure on its macroscopic behavior.