On the mechanical anisotropy of argillaceous Cobourg limestone: fabric tensor approach

The mechanical response of Cobourg limestone is anisotropic, which stems from heterogeneity of its fabric. In this work, a new fabric-dependent approach is developed for the description of strength and deformation characteristics of this rock. The quantification of fabric is carried out by employing the basic principles of stereology and the specific fabric descriptor used is the so-called mean intercept length. The results demonstrate that the material may be perceived as transversely isotropic and the mechanical response is affected by the volume fraction of argillaceous partings. The latter are spatially variable, so that the notion of Representative Elementary Volume (REV) is not, in general, applicable. A numerical study is included involving simulation of triaxial tests conducted on differently oriented samples of Cobourg limestone.