Abstract: The recognition of strain information for rock deformation localization and fracture precursors was studied through experiments. The digital speckle correlation method was employed as the observation technique. Three types of sandstone specimens were subjected to uniaxial compression tests. The study focused on the evolution of non-uniformity statistical indices, the increment of maximum shear strain, and the direction of maximum principal strain during loading. Additionally, methods for identifying deformation localization and rupture precursors based on strain information were analyzed and discussed. The results show that: (1) The abrupt change point of the evolution curve of the non-uniformity statistical index Sw coincides with the initiation time of deformation localization, and reaches the maximum value in the early stage of rupture. This behavior can serve as an indicator for identifying the initiation of deformation localization and rupture precursors. (2) The maximum shear strain increment within the localized deformation band increases abruptly in the early stage of rupture, serving as a precursor signal of rupture. (3) The direction of the maximum principal strain exhibits a sudden change during the early stages of deformation localization and rupture, showing obvious change around the localized deformation band. The magnitude of this directional change decreases with increasing distance from the localized deformation zone.

Key words: deformation localization, rupture precursors, strain information, uniaxial compression, digital speckle