Characterization of strain-burst rock fragments under a scanning electron microscope - An illustrative study

Fractures around excavations in hard, fine-grained, brittle rock sometimes display unique patterns from which an interpretation of the manner of failure/fracture propagation can be made. Igneous rock fragments from a strain-burst event at a site in Western Australia have been studied under a Scanning Electron Microscope (SEM) in order to characterize their surficial features. SEM image analysis indicates that anisotropy, a contrast in geomechanical properties, geometry and contact patterns present at the micro-scale as they do at the large mine/drive scale. It is proposed that these micro-scale features can lead to anisotropic material behaviour and stress concentrations that manifest as strain-burst events.