Experimental Study of the Strain Localization in a Rock Analogue Material at Brittle-Ductile Transition

Abstract

Many studies on strain localization of geomaterials have been carried out over the past few decades. Theoretical analysis and numerical models show that the dilatancy property strongly affects the onset of the deformation localization bands. The evolution of deformation bands, however, remains poorly known. In this work, we analyzed the initiation and evolution of strain localization in a Granular Rock Analogue Material (GRAM1) performed under axisymmetric compression at brittle-ductile transition by using Digital Image Correlation (DIC) technique. DIC provides a full-field measurement of displacement and thus allows the analysis of non-homogeneous deformation. The onset of band/fracture localization is well detected and located on the stress-strain curve. During the deformation process, the deformation bands as well as sets of sub-parallel strands which contribute the final thickness of the main shear band form sequentially. The analyses of DIC data and post-mortem sample observation enhance the understanding of the strain localization phenomena at brittle-ductile transition.