Evolution of Local Strains Under Uniaxial Compression in an Anisotropic Gypsum Sample

In the fields of geomechanical researches and applications, the study of mechanical properties of rock materials through laboratory tests is a fundamental milestone in the process of understanding and modeling the mechanical behavior and the stability assessment. In particular, the study and quantification, in laboratory samples, of the local strains and of their concentration and localization during the application of an external load may allow for a more accurate description of the material behavior. In this study, we focused on a specific gypsum rock with a strongly anisotropic structure. The strategic importance of gypsum in the construction industry and its consequent extensive exploitation by both open pit and underground quarries requires a good knowledge of its strength and stress-strain relation. We propose an application of Digital Image Correlation (DIC analysis) to the study of the evolution of local strains in gypsum rock under the application of a uniaxial compression. Resulting maps of local strains were analyzed and interpreted considering the influence of textural variability of the material. In consideration of the material anisotropy, DIC analysis was applied on two adjacent faces of a prismatic sample, allowing for a three-dimensional interpretation of strain evolution.