Residual stress in rock: insights from continuum-based micromechanical numerical modelling

Residual stresses are known to exist within the microstructure of crystalline materials as a result of material formation processes. Research has proven their existence and implications, and engineering applications have been derived for glass and metal materials. In the rock engineering field, limited research has been published on the topic in recent decades. Literature on residual stress in rock is presented regarding the formation mechanisms, magnitudes, and observed implications. Numerical modelling techniques, such as Grain-Based Modelling, can be used to gain insight into residual stresses in rock. Micromechanical numerical models were created using RS2's Voronoi network to study rock simulations that include residual stress. Using a simplified modelling sequence, a residual stress field (microstresses) was created within a hypothetical rock mineral structure and three main scenarios were simulated. The first explores a potential relationship between residual stress and compression test crack closure strain. Secondly, the possibility of sample damage due to residual stress redistribution and the influence of residual stresses on the propagation of a slot cut was investigated. Finally, the anticipated displacements around a circular excavation in a rock block containing residual stresses were examined. The numerical investigations suggest that residual stress may have real and non-negligible influence on rock behaviour. This includes the effects of crack opening/closure, sample damage, and rock displacements that are not currently accounted for with implications for rock engineering projects.