Dion Weatherley

Dion Weatherley
The University of Queensland | UQ ·  Sustainable Minerals Institute (SMI)

PhD. (Geophysics)

About

97
Publications
12,727
Reads
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1,020
Citations
Additional affiliations
January 2013 - present
The University of Queensland
Position
  • Computational Geomechanics and Comminution
October 2008 - January 2013
The University of Queensland
Position
  • Computational Geomechanics
July 2002 - September 2010
The University of Queensland
Position
  • Computational Geoscience

Publications

Publications (97)
Article
The characterisation technologies have advanced rapidly in the last decade. From a qualitative observation of minerals with optical microscopy, more quantitative techniques have emerged. Examples are the SEM-based technologies that focus on mineralogical identification at the microscale and the X-ray microtomography systems that allow identifying r...
Article
In developing a geometallurgical characterisation for comminution, the geological information, usually captured from drill core with a resolution of down to micrometre scale, is compared with the results of comminution tests. These tests require several kilograms of material and are empirical tests that do not focus on understanding the effect of o...
Conference Paper
Full-text available
Comminution is an important stage in mineral processing as it liberates valuable from non-valuable minerals. Geometallurgy applied to comminution seeks to identify relationships between the geological characteristics and the comminution response as measured in standard tests (e.g. Bond work index) to develop predictive geometallurgical models. Howe...
Article
Full-text available
Numerical modelling techniques such as the discrete element method are now well established and extensively used in many applications including solid earth geoscience, materials science, geotechnical engineering and rock mechanics. The potential for this technique in understanding comminution mechanisms has been identified as highly promising. This...
Article
The primary breakage properties of rocks such a strength (σ) and elastic moduli (i.e. Young's modulus (E) and Poisson's ratio (ѵ)) are not usually characterised at comminution scale. Traditional comminution tests such as the Bond Work Index grinding test and the Drop Weight Test are used for describing the breakage behaviour of different ores. Neve...
Data
Introduction (Version 1) The main purpose of this study guide is to publish the working Queensland Earthquake Catalog that I used while working as Senior Technical Officer, The University of Queensland Seismograph Stations (UQSS). The contents have been collected by the many Directors of UQSS and the Observors who analysed the BRS (Gardens Point),...
Article
Current tests for characterising rock breakage in comminution do not allow decoupling of rock breakage properties from the machine environment. Furthermore, it is difficult to predict the comminution behaviour of different ores or how they might behave in another breakage device. Consequently, this decoupling process is essential for comminution mo...
Conference Paper
Full-text available
This study is a step forward in the understanding of the differences in breakage properties of rocks, related to their geology. The Short Impact Load Cell (SILC) measures the effective energy used by the rock in the moment of breakage and provides an estimation of its elastic parameters. Most of the current tests for characterizing rock breakage do...
Article
Full-text available
Numerical models based on the discrete element method are used to study the fracturing process in brittle rock-like materials under direct and indirect tension. The results demonstrate the capacity of the model to capture the essential characteristics of fracture including the onset of crack propagation, stable and unstable crack growth, arrest and...
Conference Paper
Full-text available
This study aims to demonstrate the capacity of the Discrete Element Method (DEM) to model and simulate fracture in brittle rock, capture the crack propagation process and determine crack propagation rates for various levels of external loading. In the numerical experiments reported here, a macroscopically homogeneous body of brittle rock, containin...
Conference Paper
Full-text available
The stabilities of rehabilitated landforms are often threatened by the altered surface hydrology, especially the excessive surface runoff, which may cause severe water erosion and associated pollutant transport to surrounding areas. These effects would lead to pollution in waterways and render the failure of newly established vegetation. An accurat...
Conference Paper
Full-text available
The Runoff Model Based on Cellular Automata (RunCA) has been developed to simulate the surface hydrological processes at the catchment scale by integrating basic cellular automata (CA) rules with fundamental measureable hydraulic properties. In this model, a two-dimensional lattice composed of a series of rectangular cells was employed to cover the...
Article
The physical characteristics of rock, its lithology, undoubtedly influences its deformation under natural or engineering loads. Mineral texture, micro-damage, joints, bedding planes, inclusions, unconformities and faults are all postulated to alter the mechanical response of rock on different scales and under different stressing conditions. Whilst...
Article
Much of the world’s known gold has been derived from arrays of quartz veins. The veins formed during periods of mountain building that occurred as long as 3 billion years ago and were deposited by very large volumes of water that flowed along deep, seismically active faults. The veins formed under fluctuating pressures during earthquakes, but the m...
Article
Full-text available
We investigate significant heterogeneous stresses along bimaterial interfaces in laboratory and numerical experiments. These stresses, partially induced by model or experimental configuration, affect the supershear transition length and rupture speed, mode and directivity in uniaxial compression tests and dynamic rupture experiments with bimaterial...
Article
Full-text available
Pumice is an extremely effective rafting agent that can dramatically increase the dispersal range of a variety of marine organisms and connect isolated shallow marine and coastal ecosystems. Here we report on a significant recent pumice rafting and long-distance dispersal event that occurred across the southwest Pacific following the 2006 explosive...
Data
Animated trajectory model of the 2006–2007 Home Reef pumice rafts, based on the integrated surface velocity field (see also Fig. 2). Details on the calculation of the pumice trajectories are given in the Materials and Methods section. Grey areas without bathymetric information represent continental shelves of <1000 m depth, where geostrophic ocean...
Data
Data sources to historical (<200 a) pumice raft-producing eruptions shown in Figure 1. (DOCX)
Article
Numerical modelling of dynamic rupture is conducted along faults separating similar and dissimilar materials. Supershear transition is enhanced in the direction of slip of the stiffer material (the negative direction) due to the bimaterial effect whereby a decrease in normal stress in front of the crack tip supports yielding ahead of the rupture. I...
Article
An important step in the setup process of Discrete Element Model (DEM) simulations is the generation of a suitable particle packing. There are quite a number of properties such a granular material specimen should ideally have, such as high coordination number, isotropy, the ability to fill arbitrary bounding volumes and the absence of locked-in str...
Article
The Discrete Element Method (DEM[1]) has proven to be a valuable numerical method for simulating processes involving brittle failure and large deformations such as earthquakes[5], fault zone evolution[4] and granular media flow[3]. Whereas the DEM is computationally expensive compared to other numerical methods (e.g., FDM, FEM), it avoids on the ot...
Article
Bonded particle models implemented using the Discrete Element Method (DEM [1]) have proven a useful numerical laboratory to investigate the interplay between geological structure and mechanical response of rock specimens [4]. However, it is well-known that such bonded particle models fail to reproduce the ratios of compressive:tensile strength of r...
Article
Full-text available
The comminution (or breakage) of granular materials under shearing loads is conjectured to strongly influence dynamics of both natural processes (such as fault zone evolution and landslides) and man-made processes (such as underground cave mining and minerals processing). Previous laboratory [1] and numerical studies [4] have demonstrated that two...
Article
The flow dynamics of granular materials is of broad interest in both the geosciences (e.g. landslides, fault zone evolution, and brecchia pipe formation) and many engineering disciplines (e.g chemical engineering, food sciences, pharmaceuticals and materials science). At the interface between natural and human-induced granular media flow, current u...
Article
It has been noted that earthquakes rupture over step-overs. We model a non-overlapping fault-system with 2 dilational step-overs. Rupture is modelled dynamically using the Finite Element Method with elasto-plasticity along the interface and elasticity in the model region. We use the Mohr-Coulomb Failure Criterion to determine plastic displacement a...
Conference Paper
The Discrete Element Method (DEM) is a popular particle-based numerical method for simulating geophysical processes including earthquakes, rock breakage and granular flow. Often simulations consisting of thousands of particles have insufficient resolution to reproduce the micromechanics of many geophysical processes, requiring millions of particles...
Article
We present a web-based Grid job submission system which combines open-source software components and available system services freeing developers from having to deal with Grid middleware, credential management and user authentication. Instead, a Short Lived Credential Service provides the necessary user certificates, while Grisu libraries, develope...
Article
Dynamic simulations of homogeneous and bi-material fault rupture are modeled using different loading approaches. We demonstrate that a numerical method of quasi-static loading is capable of immediately loading bi-material interfaces to rupture without the iteration over multiple time steps. We show that our method is a computationally inexpensive a...
Article
Full-text available
Virtual Rock Lab (VRL) is a secure web portal designed to enable users without programming skills to construct and execute ESyS-Particle simulations. The portal covers all steps of the work flow combining interfaces that allow users to create and edit input scripts through dialogues, submit jobs to a supercomputer connected to the AuScope Grid and...
Article
Blast induced rock mass displacement can have a significant impact on ore recovery and downstream productivity in open pit mining operations. As such, several attempts have been made to develop empirical and numerical models capable of predicting both the magnitude of displacement as well as muckpile digability for given blast design inputs. Genera...
Article
Full-text available
We apply the Computational Mechanics approach to the analysis of time-series representative of geophysical measurements. The algorithm employed is the Causal-State Splitting Reconstruction (CSSR) algorithm. We address a number of data pre-processing steps which are necessary when analysing complex time-series and specific to symbolised time-series...
Article
Full-text available
Dynamic simulations of homogeneous and heterogeneous fault rupture using the finite element method are presented giving rise to both crack-like and pulse-like rupture. We employ various slip-weakening frictional laws to examine their effect on the resulting earthquake rupture speed, size and mode. More complex rupture characteristics were produced...
Article
Large earthquakes pose an almost incalculable risk, causing great destruction and, often, loss of life. While large regions of the world are susceptible to this potentially devastating natural hazard, the Asia-Pacific region is particularly vulnerable. Poignant examples in the recent past include the M∼9.2 Northern Sumatra earthquake and tsunami in...
Book
In recent years, large earthquakes in the circum-Pacific region have repeatedly demonstrated its particular vulnerability to this potentially devastating natural hazard, including the M ~ 9.2 Northern Sumatra earthquake and tsunami of 2004 which resulted in the deaths of nearly 300,000 people. In the late-1990s, major advancements in seismic resear...
Article
Dynamic simulations of rupture propagation in crustal fault systems are presented. We demonstrate the applicability of our elasto-plastic fault model for modeling dynamic rupture and wave propagation in fault systems. Firstly, we demonstrate the rich array of dynamic properties produced by our elasto-plastic finite element fault model. These are go...
Article
Full-text available
We present a method to constrain the timing of fissure generation related to late Quaternary seismic events using the uranium-series technique. Dated samples were from travertine deposits precipitated in co-seismic extensional fissures along major active faults in Western Turkey. Stable isotope and REE data indicate that the precipitation of the fi...
Conference Paper
The escript package is an extension of python. It provides an easy-to-use programming environment for numerical simulations based on the solution of partial differential equations (PDEs), while at the same time providing for fast solution of large models by performing time-intensive calculations in C++ and C. The escript functionality allows the us...
Article
Full-text available
We investigate the role of both dynamic and static stress changes on earthquake triggering. Dynamic stress triggering of earthquakes is caused by the passage of seismic waves, whereas static stress triggering is due to net slippage on a fault resulting from an earthquake. Static stress changes represented by a Coulomb failure function and its relat...
Article
Full-text available
Sliding and rolling are two outstanding deformation modes in granular media. The first one induces frictional dissipation whereas the latter one involves deformation with negligible resistance. Using numerical simulations on two-dimensional shear cells, we investigate the effect of the grain rotation on the energy dissipation and the strength of gr...
Article
The recurrence interval statistics for regional seismicity follows a universal distribution function, independent of the tectonic setting or average rate of activity (Corral, 2004). The universal function is a modified gamma distribution with power-law scaling of recurrence intervals shorter than the average rate of activity and exponential decay f...
Conference Paper
The escript package is an extension of python. It provides an easy-to-use programming environment for numerical simulations based on the solution of partial differential equations (PDEs), while at the same time providing for fast solution of large models by performing time-intensive calculations in C++ and C. The escript functionality allows the us...
Article
Full-text available
In this paper we will give a brief introduction into the Python-based modelling language escript. We will present a model for the dynamics of fault systems in the Earth's crust and then show how escript is used to implement solution algorithms for a dynamic as well as a quasi-static scenario.
Article
Full-text available
Solid earth systems simulation is now becoming feasible from the microscopic to the global scale. The ACES international cooperation has shown development of simulation capabilities for solid earth phenomena that are beyond the ability of a single group or country. Each country has different strengths, computational approaches, and laboratory and f...
Article
The critical point hypothesis of seismicity proposes that the preparation for large earthquakes involves the progressive formation of long-range spatial correlations in the regional stress field. Smaller earthquakes in the surrounding region are responsible for this correlation evolution. The observable signature of correlation evolution is acceler...
Article
Elasto-dynamic numerical simulation models and CA provide a means to study the dynamic and complex system behaviour of fault systems. Various observational, theoretical and computational evidence suggests that crustal fault systems exhibit critical point like behaviour in which correlations in the stress field grow as smaller earthquakes modify the...
Article
Full-text available
We examine the event statistics obtained from two differing simplified models for earthquake faults. The first model is a reproduction of the Block-Slider model of Carlson et al. (1991), a model often employed in seismicity studies. The second model is an elastodynamic fault model based upon the Lattice Solid Model (LSM) of Mora and Place (1994). W...
Article
— A statistical fractal automaton model is described which displays two modes of dynamical behaviour. The first mode, termed recurrent criticality, is characterised by quasi-periodic, characteristic events that are preceded by accelerating precursory activity. The second mode is more reminiscent of SOC automata in which large events are not precede...
Article
Numerical simulation models provide a means to probe the physics and dynamics of fault systems. Results from three different simulation models are presented: the particle based or micro-scale Lattice Solid Model (Mora and Place, 2002), cellular automaton models (e.g. Weatherley et al, 2002), and parallel fault continuum models (Mora and Weatherley,...
Conference Paper
Simulations provide a powerful means to help gain the understanding of crustal fault system physics required to progress towards the goal of earthquake forecasting. Cellular Automata are efficient enough to probe system dynamics but their simplifications render interpretations questionable. In contrast, sophisticated elasto-dynamic models yield mor...
Article
— We introduce a conceptual model for the in-plane physics of an earthquake fault. The model employs cellular automaton techniques to simulate tectonic loading, earthquake rupture, and strain redistribution. The impact of a hypothetical crustal elastodynamic Green's function is approximated by a long-range strain redistribution law with a r −p depe...