A Review of Rock Mass Anisotropy in Underground Mining: Characterisation, Modelling, and Monitoring

Anisotropy is a first-order control on rock mass behaviour in foliated, veined, and fabric-controlled ground, yet it remains underrepresented in routine geotechnical practice. This paper presents a review of the literature on anisotropic rock mass behaviour, organised around three identified gaps: the absence of an integrated explanation linking structure, and excavation response; the underdeveloped treatment of spatially variable anisotropy in mine-scale numerical models; and the limited incorporation of precursory monitoring evidence into mainstream geomechanical design. The review is selective rather than encyclopaedic, covering experimental characterisation of directional strength and stiffness, the mechanical role of microstructure and fabric morphology, excavation damaged zone development, constitutive and spatial modelling strategies, seismic source characterisation, laboratory precursor detection, and data collection practice. The review finds that anisotropy changes the path to failure and the spatial organisation of damage, not merely the peak strength, and that constitutive sophistication without a geologically admissible representation of fabric is insufficient to reproduce the mechanism, location, and temporal evolution of damage around underground excavations.