Numerical Exploration of Residual Stress Mechanisms in Rock
Date
2024-08-18
Authors
Trzop, Maxzender
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Abstract
Residual stresses are known to exist within the microstructure of crystalline materials as a
result of material formation processes and exists in a state of equilibrium with their own
internal forces. Research has proven their existence, and engineering applications have been
derived for glass and metal to achieve desirable material properties. In the field of rock
mechanics and rock engineering, the existence of residual stress has been acknowledged,
but beyond that, little research has been performed to investigate their behaviour and
implications and they are often omitted from design considerations due to their state of
equilibrium. Using numerical modelling techniques such as grain-based modelling, insights
on the effects of residual stress in rock can be explored. Grain-based models were created in
2D with RS2, and in 3D with 3DEC, to explore potential implications for residual stress in
the field of rock mechanics and rock engineering. Methods to implement residual stress in
numerical models were developed and used to explore the effects of residual stress on
modelling outcomes. In RS2, three main implications were investigated. The first examines
a relationship between residual stress and crack closure strains in compression tests. The
second investigates the influence of residual stresses on the formation and propagation of
damage (microcracks) within rock specimens. The final simulation relates to the stresses
and displacements associated with a mobilized residual stress field due to the addition of a
circular excavation in a rock block. In 3DEC, the formation of damage due to unloading a
specimen containing residual stresses was examined. Compression tests were performed on
the unloaded specimens to investigate for crack closure strains as a result of the damaged
formed through residual stress redistribution during unloading. The investigations
undertaken in this study suggest that residual stresses have a real and non-negligible
influence on rock behaviour and their omission may not be a valid approach when
performing design in rock that contains these stresses.
Description
Residual stresses exist in materials isolated from applied loading and are typically omitted from designs and studies. This research investigates potential implications for residual stress in rock mechanics and rock engineering through the use of 2D continuum and 3D discontinuum models.
Keywords
Residual Stress, Micromechanical Modelling, Crack Closure, Damage