Strain localization in rocks under uniaxial compression and direct tension

This work is devoted to the investigation of spatio-temporal strain localizations under uniaxial quasistatic compression and tension of rocks with the use of the digital image correlation method. Conducted experiments allow us to establish specific forms of strain localization under uniaxial tension of sylvinite and uniaxial compression of granite. Tensile experiment showed the existence of equidistant zones of strain localization and deformation activation of one of zones at the stage of macrofracture initiation. For uniaxial compression tests of granite, it has been found that process of strain localization was realized only in the form of slow deformation waves with different directions of displacement inside: the longitudinal and transverse waves. The velocity of such waves decreased up to 10⁻⁴ m/s with increasing of applied load. At the prefracture stage localized strain waves of different types concentrated near the exit area of main crack on the specimen surface.