Pétrofabrique et propriétés mécaniques des argilites

The petrofabric of mudstones influences their thermal, hydraulic and mechanical properties. Measurements of thermal diffusivity, permeability and velocity of ultrasonic waves show that the anisotropy of these properties in this rock is rather low. The diminution of Biot coefficient with axial stress cannot be explained only by the diminution of porosity even by considering an incompressible matrix to 1% for an axial stress varying from 8 to 24 MPa corresponds. The origin of the diminution could be explained by the loss of connection of part of the porous system, hitherto connected, under the effect of an increasing axial stress. An isotropic elastoplastic model is a reasonable approach for the description of the mechanical behaviour of mudstone. However, it is useful to take into account the damage by microfissuring, which could not be neglected and must be considered coupled with plasticity. To cite this article: F. Homand et al., C. R. Geoscience 338 (2006).