Nucleation and Growth of Damage in Rock Masses and on Sliding Surfaces

We are investigating the failure of rock masses resulting from the complex physics of microscopic dynamical processes in rocks, as manifested in the nucleation and growth of defects, microcracks, damage, and macroscopic fracture. These processes are a result of the complex emergent dynamics of self-organizing geological materials which we analyze using the methods of statistical physics and large scale simulations employing both molecular dynamics and Monte Carlo methods. A particular example is the nucleation and growth of damage on sliding surfaces associated with frictional failure. Fully interacting fields of defects and damage are generally not included in most current models for material deformation. Instead, defect density and damage fields are assumed to be non-interacting or dilute, implying a strictly mean field approach. We use statistical physics methods to understand the dynamics of interacting defect and damage fields, made possible by the construction and use of statistical field theories, to greatly improve our predictive capability for the macroscopic failure of materials. The important quantities to compute are the nucleation rate, or its inverse, lifetime to failure. We also discuss applications of this research to rock deformation across a range of spatial and temporal scales.