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