New approaches to characterize brittle fracture and damage in fractured rock masses

The importance of characterising intact rock fracturing and rock mass damage in rock engineering has received increased attention over the last decade, as excavations have progressed to greater depths. A wide variety of sophisticated numerical modelling codes have been developed to simulate brittle fracture both with and without the incorporation of discrete fracture networks. At the same time, new remote sensing methods of characterising rock masses in the field have been developed using high resolution photography, ground-based photogrammetry, airborne/ground-based LiDAR, thermal and hyperspectral imaging. Based on recent research, the authors present examples of the characterization of intact rock fracture and damage in rock masses in both surface and underground environments. Conventional methods of engineering mapping of rock slopes and underground excavations have in the past emphasized the geometry of natural discontinuities with limited attention devoted to intact rock fracturing and damage. We first review remote sensing methods for mapping damage in the field and then present examples of its use in mapping both seepage and intact rock fracture/step-paths and rock bridges. The use of remote sensing methods in mapping rock mass damage is discussed with reference to high natural and engineered rock slopes/landslides and underground excavations. Important concepts of rock mass damage are reviewed with a focus on active damage processes and suggested methods of damage characterisation. Varied approaches to modelling damage and brittle fracture using numerical models are illustrated. Finally, examples are presented of the potential application of state-of-the-art mixed reality holographic imagery in improved visualisation of fractured rock masses in rock engineering.