The geomechanics research thematic focuses on the dynamics and physics of earth processes on scales from microns to tens of metres applying methodologies of computational solid mechanics and the discrete element method.
Many of the processes that shape the surface of our planet involve brittle deformation of the Earth's crust and/or flow of granular materials. These processes include earthquakes, landslides and erosion. We apply the discrete element method, a particle-based simulation technique, to model such processes aiming to gain insight into the physics of brittle failure and granular flow. Our research has implications for geo-hazards, minerals science (particularly comminution) and mass-mining.
Earthquake faults typically consist of a broad zone of broken rock known as fault gouge. Our research has demonstrated that earthquake nucleation within granular fault zones involves self-organisation to form thin bands along which the majority of slip occurs. The formation of such bands is correlated with a significant reduction in the macroscopic frictional strength of the fault thus permitting the passage of earthquake ruptures within expenditure of energy.
A comprehensive theory for the brittle failure of materials remains an elusive target for scientists despite abundant laboratory and field observations. We aim to provide a virtual laboratory for simulating rock breakage by implementing a novel particle interaction law designed to reproduce the gross characteristics of brittle failure as observed in laboratory experiments. Successful simulation of 3-dimensional wingcrack formation validates our ability to reproduce one of the most fundamental features of rock breakage. Current research is focused upon calibration of the model for simulating the fragmentation of granular materials under shear or impact forces. This is being done in collaboration with minerals comminution experts at JKMRC who perform laboratory fragmentation experiments.
Another poorly understand process involves the flow of granular materials. Under some circumstances such materials display distinctly fluid-like dynamics whilst other circumstances give rise to rigid dynamics. An understanding of granular flow is of great importance in the mining, minerals processing and manufacturing industries. A popular and inexpensive mass-mining technique, block caving, involves the in-situ fragmentation of an ore body and extraction via silo flow through drawpoints below. Field and laboratory observations confirm that significant secondary fragmentation and migration of fine material occurs during block caving, prediction of which may result in significant cost reductions in mining operations. Utilising our discrete element method, we are studying the dynamics of granular flow within block caves, aiming to understand the processes controlling secondary fragmentation and the migration of fines within caving flows.
The geomechanics research thematic currently has 4 major projects:
|Fault Zone Processes
|Brittle Rock Failure