Earth Systems Science Computational Centre Publications  UQ eSpace
http://espace.library.uq.edu.au/
The University of Queensland
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3D mesh generation in geocomputing
http://espace.library.uq.edu.au/view/UQ:204398
20100426T19:22:37Z
Xing, Huilin; Yu, Wenhui; Zhang, Ji

3D Simulations of Block Caving Flow Using ESySParticle
http://espace.library.uq.edu.au/view/UQ:177819
20090520T17:24:09Z
William Rodney Hancock; Weatherley, Dion K.

3rd ACES Workshop Proceedings
http://espace.library.uq.edu.au/view/UQ:94257
20070822T10:27:18Z

A 2D finiteelement method for simulating the physics of fault systems during earthquake cycles
http://espace.library.uq.edu.au/view/UQ:103209
20070823T21:26:03Z
Mora, P. R.; Saez, E.; Weatherley, D. K.; Gross, L.; Wang, C. M.

A 2D numerical model for simulating the physics of fault systems
http://espace.library.uq.edu.au/view/UQ:39499
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 elastodynamic models yield more convincing results but are too computationally demanding to explore phase space. To help bridge this gap, we develop a simple 2D elastodynamic model of parallel fault systems. The model is discretised onto a triangular lattice and faults are specified as split nodes along horizontal rows in the lattice. A simple numerical approach is presented for calculating the forces at medium and split nodes such that general nonlinear frictional constitutive relations can be modeled along faults. Single and multifault simulation examples are presented using a nonlinear frictional relation that is slip and sliprate dependent in order to illustrate the model.
20070813T13:44:47Z
Mora, P. R.; Weatherley, D. K.

A 3D virtual earth simulator for earthquake microphysics: LSMearth
http://espace.library.uq.edu.au/view/UQ:96782
20070824T00:47:59Z
Mora, P. R.; Place, D. G.

A boundary focused quadrilateral mesh generation algorithm for multimaterial structures
http://espace.library.uq.edu.au/view/UQ:287738
This paper describes a new boundary focused mesh generation algorithm. The algorithm produces quadrilateral meshes from images of multimaterial structures. The challenge of meshing such images is to create high quality elements which are aligned with complex material boundaries. The approach proposed in this paper uses the following steps: (1) extract boundaries according to pixel colours; (2) smooth the jagged boundaries; (3) generate geodesic isolines aligned with smoothed boundaries; (4) generate a mesh from the boundaries and isolines; (5) optimize the mesh using the " Pisces" pattern (which is introduced in this paper). Application examples are presented to contrast the reliability and effectiveness of the new algorithm with existing approaches.
20121223T00:28:17Z
Liu, Yan; Xing, H. L.

Absorbing bourndary and freesurface conditions in the phononic lattice solid by interpolation.
http://espace.library.uq.edu.au/view/UQ:142330
20080610T13:23:25Z
Huang, L.; Mora, P. R.; Fehler, M.

Accelerating energy release prior to large events in simulated earthquake cycles: implications for earthquake forecasting
http://espace.library.uq.edu.au/view/UQ:150855
20080606T16:50:16Z
Mora, P. R.; Place, D. G.

Accelerating precursory activity in statistical fractal automata
http://espace.library.uq.edu.au/view/UQ:67270
20070815T02:36:08Z
Weatherley, D. K.; Mora, P. R.

Accelerating precursory activity within a class of earthquake analogue automata
http://espace.library.uq.edu.au/view/UQ:74392
A statistical fractal automaton model is described which displays two modes of dynamical behaviour. The first mode, termed recurrent criticality, is characterised by quasiperiodic, characteristic events that are preceded by accelerating precursory activity. The second mode is more reminiscent of SOC automata in which large events are not preceded by an acceleration in activity. Extending upon previous studies of statistical fractal automata, a redistribution law is introduced which incorporates two model parameters: a dissipation factor and a stress transfer ratio. Results from a parameter space investigation indicate that a straight line through parameter space marks a transition from recurrent criticality to unpredictable dynamics. Recurrent criticality only occurs for models within one corner of the parameter space. The location of the transition displays a simple dependence upon the fractal correlation dimension of the cell strength distribution. Analysis of stress field evolution indicates that recurrent criticality occurs in models with significant longrange stress correlations. A constant rate of activity is associated with a decorrelated stress field.
20070815T05:12:20Z
Weatherley, D; Mora, P

Accelerating seismic energy release and evolution of event time and size statistics: Results from two heterogeneious cellular automaton models.
http://espace.library.uq.edu.au/view/UQ:142328
20080610T13:23:19Z
Jaume, S. C.; Weatherley, D. K.; Mora, P. R.

Accelerating seismic energy release and evolution of event time and size statistics: Results from two heterogeneous cellular automaton models
http://espace.library.uq.edu.au/view/UQ:61053
20070814T16:56:51Z
Jaume, S. C.; Weatherley, D. K.; Mora, P. R.

Accelerating seismic energy release and evolution of event time and size statistics: Results from two heterogeneous cellular automaton models
http://espace.library.uq.edu.au/view/UQ:37046
The evolution of event time and size statistics in two heterogeneous cellular automaton models of earthquake behavior are studied and compared to the evolution of these quantities during observed periods of accelerating seismic energy release Drier to large earthquakes. The two automata have different nearest neighbor laws, one of which produces selforganized critical (SOC) behavior (PSD model) and the other which produces quasiperiodic large events (crack model). In the PSD model periods of accelerating energy release before large events are rare. In the crack model, many large events are preceded by periods of accelerating energy release. When compared to randomized event catalogs, accelerating energy release before large events occurs more often than random in the crack model but less often than random in the PSD model; it is easier to tell the crack and PSD model results apart from each other than to tell either model apart from a random catalog. The evolution of event sizes during the accelerating energy release sequences in all models is compared to that of observed sequences. The accelerating energy release sequences in the crack model consist of an increase in the rate of events of all sizes, consistent with observations from a small number of natural cases, however inconsistent with a larger number of cases in which there is an increase in the rate of only moderatesized events. On average, no increase in the rate of events of any size is seen before large events in the PSD model.
20070813T12:10:20Z
Jaume, SC; Weatherley, D; Mora, P

Accelerating seismic energy release before moderate to large earthquakes
http://espace.library.uq.edu.au/view/UQ:150845
20080606T16:49:52Z
Jaume, S. C.; Mora, P. R.; Bufe, C. G.

Accelerating seismic energy release in two elastic models of seismic rupture
http://espace.library.uq.edu.au/view/UQ:150877
20080606T16:51:10Z
Winter, M.

Accelerating seismic moment release, the critical point hypothesis and predicting macroscopic failure
http://espace.library.uq.edu.au/view/UQ:149059
20080606T15:09:27Z
Weatherley, D. K.; Mora, P. R.

ACcESS: Australia's contribution to the iSERVO Institute's development
http://espace.library.uq.edu.au/view/UQ:75785
The new Australian Computational Earth Systems Simulator research facility provides a virtual laboratory for studying the solid earth and its complex system behavior. The facility's capabilities complement those developed by overseas groups, thereby creating the infrastructure for an international computational solid earth research virtual observatory.
20070815T06:03:39Z
Mora, P; Muhlhaus, H; Gross, L; Xing, H; Weatherley, D; Abe, S; Latham, S; Moresi, L

A characteristic length scale in confined elastic buckling of a force chain
http://espace.library.uq.edu.au/view/UQ:255508
We examine the confined elastic buckling of a single Nparticle force chain. For a given set of material parameters, a characteristic loadcarrying capacity is attained for a clearly defined range of force chain lengths N ≥ L*. The rotation and translation of particles along periodically located segments of the critical buckling mode, each of length L*, are on average consistent with those for particles inside the shear band. Preliminary results from postbuckling analysis show that the critical buckling mode is unstable and that buckling culminates in a localized response over one of these segments where observed shear band kinematics prevail. Thus, the localized buckling response is characterized by the rotation of a finite number of particles with a clearly defined length L*. For a wide range of material properties, L* is around eight particle diameters  the observed shear band thickness for many granular materials, most notably sand.
20111013T11:41:58Z
Tordesillas, Antoinette; Hunt, Giles; Shi, Jingyu

A combined computational approach towards earthquake forecasting
http://espace.library.uq.edu.au/view/UQ:204568
Earth scientists are probing the predictability issue of earthquakes from basically two directions: one group of researchers uses the statistical physics based methods such as LURR (LoadUnload Response Ratio), AMR (Accelerate seismic Moment Release) and Pattern Informatics. They ignore the details inside the crust but instead only observe the change of the crust as a whole. By comparing the changing pattern of a target block of crust with the pattern in other areas where the history of the pattern are known, they can deduce the state of the crust and make temporal prediction of the stability of that crust.
20100430T09:17:42Z
Xing, H. L.; Yin, C.

A consistent pointsearching algorithm for solution interpolation in unstructured meshes consisting of 4node bilinear quadrilateral elements
http://espace.library.uq.edu.au/view/UQ:35696
To translate and transfer solution data between two totally different meshes (i.e. mesh 1 and mesh 2), a consistent pointsearching algorithm for solution interpolation in unstructured meshes consisting of 4node bilinear quadrilateral elements is presented in this paper. The proposed algorithm has the following significant advantages: (1) The use of a pointsearching strategy allows a point in one mesh to be accurately related to an element (containing this point) in another mesh. Thus, to translate/transfer the solution of any particular point from mesh 2 td mesh 1, only one element in mesh 2 needs to be inversely mapped. This certainly minimizes the number of elements, to which the inverse mapping is applied. In this regard, the present algorithm is very effective and efficient. (2) Analytical solutions to the local co ordinates of any point in a fournode quadrilateral element, which are derived in a rigorous mathematical manner in the context of this paper, make it possible to carry out an inverse mapping process very effectively and efficiently. (3) The use of consistent interpolation enables the interpolated solution to be compatible with an original solution and, therefore guarantees the interpolated solution of extremely high accuracy. After the mathematical formulations of the algorithm are presented, the algorithm is tested and validated through a challenging problem. The related results from the test problem have demonstrated the generality, accuracy, effectiveness, efficiency and robustness of the proposed consistent pointsearching algorithm. Copyright (C) 1999 John Wiley & Sons, Ltd.
20070813T11:14:51Z
Zhao, CB; Hobbs, BE; Muhlhaus, HB; Ord, A

A continuum model for periodic twodimensional block structures
http://espace.library.uq.edu.au/view/UQ:57706
A continuum model for regular block structures is derived by replacing the difference quotients of the discrete equations by corresponding differential quotients. The homogenization procedure leads to an anisotropic Cosserat Continuum. For elastic block interactions the dispersion relations of the discrete and the continuous models are derived and compared. Yield criteria for block tilting and sliding are formulated. An extension of the theory for large deformation is proposed. (C) 1997 by John Wiley & Sons, Ltd.
20070813T16:51:05Z
Sulem, J; Muhlhaus, HB

Acta Geotechnica: Special issue on Geodynamic Modeling
http://espace.library.uq.edu.au/view/UQ:220537
20101116T11:41:16Z

Adaptive meshing/remeshing and its application to geocomputing
http://espace.library.uq.edu.au/view/UQ:204723
20100504T09:13:41Z
Yu, W; Xing, H. L.

Adaptive static/dynamic finite element modelling of interacting fault systems
http://espace.library.uq.edu.au/view/UQ:103214
20070823T21:26:13Z
Xing, H.; Mora, P. R.

A DEM study on the effective thermal conductivity of granular assemblies
http://espace.library.uq.edu.au/view/UQ:225128
A discrete element method (DEM) is developed to simulate the heat transfer in granular assemblies in vacuum with consideration of the thermal resistance of rough contact surfaces. Average heat flux is formulated by the positions and heat flow rates of particles on the boundaries of the granular assemblies. Average temperature gradient is given as a bestfit formulation, which is computed from the relative position and temperature of particles. With the thermal boundary condition imposed on the border region, the effective thermal conductivity (ETC) of granular assemblies can be calculated from the average heat flux and temperature gradient obtained from DEM simulations. Moreover, the effects of particle size, solid volume fraction and coordination number on the ETC are also investigated. Simulation results show that granular assemblies with coarse particles and under large external compression forces exhibit a better heat conduction behavior. The effects of particle size and external compression forces on the ETC are in good agreement with experiment observations. © 2010.
20101219T00:03:10Z
Zhang, H. W.; Zhou, Q.; Xing, H. L.; Muhlhaus, H.

A director theory for viscoelastic folding instabilities in multilayered rock
http://espace.library.uq.edu.au/view/UQ:38323
A model for finely layered viscoelastic rock proposed by us in previous papers is revisited and generalized to include couple stresses. We begin with an outline of the governing equations for the standard continuum case and apply a computational simulation scheme suitable for problems involving very large deformations. We then consider buckling instabilities in a finite, rectangular domain. Embedded within this domain, parallel to the longer dimension we consider a stiff, layered beam under compression. We analyse folding up to 40% shortening. The standard continuum solution becomes unstable for extreme values of the shear/normal viscosity ratio. The instability is a consequence of the neglect of the bending stiffness/viscosity in the standard continuum model. We suggest considering these effects within the framework of a couple stress theory. Couple stress theories involve second order spatial derivatives of the velocities/displacements in the virtual work principle. To avoid C1 continuity in the finite element formulation we introduce the spin of the cross sections of the individual layers as an independent variable and enforce equality to the spin of the unit normal vector to the layers (the director of the layer system) by means of a penalty method. We illustrate the convergence of the penalty method by means of numerical solutions of simple shears of an infinite layer for increasing values of the penalty parameter. For the shear problem we present solutions assuming that the internal layering is oriented orthogonal to the surfaces of the shear layer initially. For high values of the ratio of the normalto the shear viscosity the deformation concentrates in thin bands around to the layer surfaces. The effect of couple stresses on the evolution of folds in layered structures is also investigated. (C) 2002 Elsevier Science Ltd. All rights reserved.
20070813T13:03:04Z
Muhlhaus, HB; Dufour, F; Moresi, L; Hobbs, B

A Double Hardening ThermoMechanical Constitutive Model for Over Consolidated Clays
http://espace.library.uq.edu.au/view/UQ:204402
20100426T20:05:57Z
Liu, E.; Xing, Huilin

Advances in geocomputing: Lecture notes in earth sciences
http://espace.library.uq.edu.au/view/UQ:204396
20100426T19:11:50Z

Advances in simulating the nonlinear physics of earthquakes using the particlebased Lattice Solid Model: evidence for the critical point hypothesis for earthquakes
http://espace.library.uq.edu.au/view/UQ:150860
20080606T16:50:29Z
Mora, P. R.; Place, D. G.; Jaume, S. C.; Abe, S.

A dynamic finite element method for simulating the physics of fault systems
http://espace.library.uq.edu.au/view/UQ:101595
20070823T20:16:35Z
Saez, E.; Mora, P. R.; Gross, L.; Weatherley, D. K.

A finite element analysis of tidal deformation of the entire earth with a discontinuous outer layer
http://espace.library.uq.edu.au/view/UQ:129784
Tidal deformation of the Earth is normally calculated using the analytical solution with some simplified assumptions, such as the Earth is a perfect sphere of continuous media. This paper proposes an alternative way, in which the Earth crust is discontinuous along its boundaries, to calculate the tidal deformation using a finite element method. An inhouse finite element code is firstly introduced in brief and then extended here to calculate the tidal deformation. The tidal deformation of the Earth due to the Moon was calculated for an geophysical earth model with the discontinuous outer layer and compared with the continuous case. The preliminary results indicate that the discontinuity could have different effects on the tidal deformation in the local zone around the fault, but almost no effects on both the locations far from the fault and the global deformation amplitude of the Earth. The localized deformation amplitude seems to depend much on the relative orientation between the fault strike direction and the loading direction (i.e. the location of the Moon) and the physical property of the fault.
20080218T14:48:43Z
Xing, H. L.; Zhang, J.; Yin, C.

A finite element method for simulating the physics of fault systems
http://espace.library.uq.edu.au/view/UQ:101686
20070823T20:20:17Z
Saez, E.; Mora, P. R.; Gross, L.; Weatherley, D. K.

A highlevel programming language for modelling the earth
http://espace.library.uq.edu.au/view/UQ:101685
20070823T20:20:16Z
Davies, M.; Gerschwitz, J. C.; Gross, L.

A Lagrangian Integration Point Finite Element Method for Large Deformation Modeling of Viscoelastic Geomaterials
http://espace.library.uq.edu.au/view/UQ:8538
We review the methods available for large deformation simulations of geomaterials before presenting a Lagrangian integration point finite element method designed specifically to tackle this problem. In our ELLIPSIS code, the problem domain is represented by an Eulerian mesh and an embedded set of Lagrangian integration points or particles. Unknown variables are computed at the mesh nodes and the Lagrangian particles carry history variables during the deformation process. This method is ideally suited to model fluidlike behavior of continuum solids which are frequently encountered in geological contexts. We present benchmark examples taken from the geomechanics area.
20060324T00:00:00Z
Moresi, Louis N.; Dufour, Frederic; Muhlhaus, Hans

A Lattice Solid Model to simulate the microphysics of earthquakes: toward 3D large scale simulations
http://espace.library.uq.edu.au/view/UQ:150867
20080606T16:50:45Z
Place, D. G.; Mora, P. R.

Algebraic upwinding with flux correction in 3D numerical simulations in geosciences
http://espace.library.uq.edu.au/view/UQ:256326
The solution of transport problems is a key component for most numerical simulations in Geosciences, for instance in mineralization, CO2 sequestration and ground water ﬂow. Characteristic features of these transport problems are large jumps in material coefﬁcients, in particular through changes in rock porosity. In the paper we present a general framework for solving a general type of transport problems using an operator splitting approach and algebraic upwinding with ﬂux correction. We will test the proposed framework for a typical problem arising from modelling mineralization in a sedimentary structure. The tests indicate that the backward Euler scheme with ﬂux correction has the potential of providing transport solver for Geoscience applications which is weakly scalable for practical scenarios.
20111017T10:36:31Z
Gross, Lutz; Gao, Lin

A micromechanical approach for the study of contact erosion
http://espace.library.uq.edu.au/view/UQ:320034
In the present paper, a simulation framework is presented coupling the mechanics of fluids and solids to study the contact erosion phenomenon. The fluid is represented by the lattice Boltzmann method (LBM), and the soil particles are modelled using the discrete element method (DEM). The coupling law considers accurately the momentum transfer between both phases. The scheme is validated by running simulations of the drag coefficient and the Magnus effect for spheres and comparing the observations with results found in the literature. Once validated, a soil composed of particles of two distinct sizes is simulated by the DEM and then hydraulically loaded with an LBM fluid. It is observed how the hydraulic gradient compromises the stability of the soil by pushing the smaller particles into the voids between the largest ones. The hydraulic gradient is more pronounced in the areas occupied by the smallest particles due to a reduced constriction size, which at the same time increases the buoyancy acting on them. At the mixing zone, where both particle sizes coexist, the fluid transfers its momentum to the small particles, increasing the erosion rate in the process. Moreover, the particles show an increase in their angular velocity at the mixing zone, which implies that the small particles roll over the large ones, greatly reducing the friction between them. The results offer new insights into the erosion and suffusion processes, which could be used to better predict and design structures on hydraulically loaded soils.
20131224T13:19:19Z
GalindoTorres, S. A.; Scheuermann, A.; Muhlhaus, H. B.; Williams, D. J.

A model comparison study of largescale mantlelithosphere dynamics driven by subduction
http://espace.library.uq.edu.au/view/UQ:174784
Modelling subduction involves solving the dynamic interaction between a rigid (solid yet deformable) plate and the fluid (easily deformable) mantle. Previous approaches neglected the solidlike behavior of the lithosphere by only considering a purely fluid description. However, over the past 5 years, a more selfconsistent description of a mechanically differentiated subducting plate has emerged. The key feature in this mechanical description is incorporation of a strong core which provides small resistance to plate bending at subduction zones while simultaneously providing adequate stretching resistance Such that slab Pull drives forward plate motion. Additionally, the accompanying numerical approaches for simulating largescale lithospheric deformation processes coupled to the underlying viscous mantle flow, have been become available. Here we put forward three fundamentally different numerical strategies, each of which is capabable of treating the advection of mechanically distinct materials that describe the subducting plate. We demonstrate their robustness by calculating the numerically challenging problem of subduction of a 6000 kin wide slab at highresolution in threedimensions, the successfuly achievement of which only a few codes in the world can presently even attempt. In spite of the differences of the approaches, all three codes pass the simple qualitative test of developing an "Sbend" trench curvature previously observed in similar models. While reproducing this emergent feature validates that the lithospheremantle interaction has been correctly modelled, this is not a numerical benchmark in the traditional sense where the objective is for all codes to achieve exact agreement on a unique numerical Solution. However, we do provide some quantitative comparisons such as trench and plate kinematics in addition to discussing the strength and weaknesses of the individual approaches. Consequently, we believe these developed algorithms can now be applied to study the parameters involved in the dynamics of subduction and offer a toolbox to be used by the entire geoscience community. (C) 2008 Elsevier B.V. All rights reserved.
20090408T20:21:30Z
OzBench, Mark; RegenauerLieb, Klaus; Stegman, Dave R.; Morra, Gabriele; Farrington, Rebecca; Hale, Alina; May, David, A.; Freeman, Justin; Bourgouin, Laurent; Muhlhaus, Hans; Moresi, Louis

Analysis of porefluid pressure gradient and effective verticalstress gradient distribution in layered hydrodynamic systems
http://espace.library.uq.edu.au/view/UQ:35057
A theoretical analysis is carried out to investigate the porefluid pressure gradient and effective verticalstress gradient distribution in fluid saturated porous rock masses in layered hydrodynamic systems. Three important concepts, namely the critical porosity of a porous medium, the intrinsic Forefluid pressure and the intrinsic effective vertical stress of the solid matrix, are presented and discussed. Using some basic scientific principles, we derive analytical solutions and explore the conditions under which either the intrinsic porefluid pressure gradient or the intrinsic effective verticalstress gradient can be maintained at the value of the lithostatic pressure gradient. Even though the intrinsic porefluid pressure gradient can be maintained at the value of the lithostatic pressure gradient in a single layer, it is impossible to maintain it at this value in all layers in a layered hydrodynamic system, unless all layers have the same permeability and porosity simultaneously. However, the intrinsic effective verticalstress gradient of the solid matrix can be maintained at a value close to the lithostatic pressure gradient in all layers in any layered hydrodynamic system within the scope of this study.
20070813T10:35:14Z
Zhao, CB; Hobbs, BE; Muhlhaus, HB

Analysis of slipweakening frictional laws with static restrengthening and their implications on the scaling, asymmetry and mode of dynamic rupture on homogeneous and bimaterial interfaces
http://espace.library.uq.edu.au/view/UQ:119832
Dynamic simulations of homogeneous and heterogeneous fault rupture using the finite element method are presented giving rise to both cracklike and pulselike rupture. We employ various slipweakening frictional laws to examine their effect on the resulting earthquake rupture speed, size and mode. More complex rupture characteristics were produced with more strongly slipweakening frictional laws, and the degree of slipweakening had to be finely tuned to reproduce realistic earthquake rupture characteristics. Rupture propagation on a fault is controlled by the constitutive properties of the fault. A dynamic elastoplastic constitutive law for the interface friction at the fault is formulated based on the Coulomb failure criterion and applied in a way analogous to nonassociated elastoplasticity. We provide benchmark tests of our method against other reported solutions in the literature. We demonstrate the applicability of our elastoplastic fault model for modeling dynamic rupture and wave propagation in fault systems, and the rich array of dynamic properties produced by our elastoplastic finite element fault model. These are governed by a number of model parameters including: the spatial and material heterogeneity of the fault, the fault strength, and not least of all the frictional law employed. Asymmetric bilateral fault rupture was produced for the heterogeneous case, where the degree of heterogeneity influenced the rupture speed in the different propagation directions.
20071024T12:30:05Z
OlsenKettle, Louise; Weatherley, Dion; Saez, Estelle; Gross, Lutz; Muhlhaus, Hans; Xing, Huilin

Analysis of slipweakening frictional laws with static restrengthening and their implications on the scaling, asymmetry, and mode of dynamic rupture on homogeneous and biomaterial interfaces
http://espace.library.uq.edu.au/view/UQ:174782
Dynamic simulations of homogeneous, heterogeneous and bimaterial fault rupture using modified slipweakening frictional laws with static restrengthening are presented giving rise to both cracklike and pulselike rupture. We demonstrate that pulselike rupture is possible by making a modification of classical slipweakening friction to include static restrengthening. We employ various slipweakening frictional laws to examine their effect on the resulting earthquake rupture speed, size and mode. More complex rupture characteristics were produced with more strongly slipweakening frictional laws, and the degree of lipweakening had to be finely tuned to reproduce realistic earthquake rupture characteristics. Rupture propagation on a fault is controlled by the constitutive properties of the fault. We provide benchmark tests of our method against other reported solutions in the literature. We demonstrate the applicability of our elastoplastic fault model for modeling dynamic rupture and wave propagation in fault systems, and the rich array of dynamic properties produced by our elastoplastic finite element fault model. These are governed by a number of model parameters including: the spatial heterogeneity and material contrast across the fault, the fault strength, and not least of all the frictional law employed. Asymmetric bilateral fault rupture was produced for the bimaterial case, where the degree of material contrast influenced the rupture speed in the different propagation directions.
20090408T20:12:28Z
OlsenKettle, L. M.; Weatherley, D.; Saez, E.; Gross, L.; Muhlhaus, H. B.; Xing, H. L.

Analysis of steadystate heat transfer through midcrustal vertical cracks with upward throughflow in hydrothermal systems
http://espace.library.uq.edu.au/view/UQ:38712
We conduct a theoretical analysis of steadystate heat transfer problems through midcrustal vertical cracks with upward throughflow in hydrothermal systems. In particular, we derive analytical solutions for both the far field and near field of the system. In order to investigate the contribution of the forced advection to the total temperature of the system, two concepts, namely the critical Peclet number and the critical permeability of the system, have been presented and discussed in this paper. The analytical solution for the far field of the system indicates that if the porefluid pressure gradient in the crust is lithostatic, the critical permeability of the system can be used to determine whether or not the contribution of the forced advection to the total temperature of the system is negligible. Otherwise, the critical Peclet number should be used. For a crust of moderate thickness, the critical permeability is of the order of magnitude of 10(20) m(2), under which heat conduction is the overwhelming mechanism to transfer heat energy, even though the porefluid pressure gradient in the crust is lithostatic. Furthermore, the lower bound analytical solution for the near field of the system demonstrates that the permeable vertical cracks in the middle crust can efficiently transfer heat energy from the lower crust to the upper crust of the Earth. Copyright (C) 2002 John Wiley Sons, Ltd.
20070813T13:16:39Z
Zhao, CB; Hobbs, BE; Muhlhaus, HB; Ord, A; Lin, G

Analytical and numerical investigation of fracture dominated thermofluid flow in geothermal reservoir
http://espace.library.uq.edu.au/view/UQ:139060
20080602T17:20:57Z
Xu, H.; Xing, H.; Wyborn, D.; Mora, P. R.

Analytical solutions for porefluid flow focusing within inclined elliptic inclusions in porefluidsaturated porous rocks: Solutions derived in an elliptical coordinate system
http://espace.library.uq.edu.au/view/UQ:124055
Exact analytical solutions have been derived rigorously for the porefluid velocity, porefluidflow focusing factor, stream function and excess porefluid pressure around and within a buried inclined elliptic inclusion in porefluidsaturated porous rocks. The geometric characteristics of the buried inclined elliptic inclusion are represented by the aspect ratio and dip angle of the inclusion, while the hydrodynamic characteristic is represented by the permeability ratio of the elliptic inclusion to its surrounding rock. Since an elliptic inclusion of any aspect ratio can be used to approximately represent geological faults and cracks, the present analytical solutions can be used to investigate the porefluidflow patterns around buried faults and cracks within the crust of the Earth. Therefore, the present analytical solution not only provides a better understanding of the physics behind the porefluidflow focusing problem around and within buried faults and cracks, but also provides a valuable benchmark solution for validating any numerical method in dealing with this kind of porefluidflow focusing problem. The porefluidflow focusing factor of a buried elliptic inclusion is demonstrated to be dependent on the aspect ratio, the permeability ratio and the dip angle.
20080125T17:02:03Z
Zhao, Chongbin; Hobbs, B. E; Ord, A.; Peng, Shenglin; Liu, Liangming; Muhlhaus, H. B.

An analysis of the strength of anisotropic granular assemblies via discrete methods
http://espace.library.uq.edu.au/view/UQ:333332
20140623T17:30:24Z
Galindo Torres, Sergio; Pedroso, Dorival; Williams, David; Muhlhaus, Hans

Anatomy of sealevel change over the last glacial cycle as preserved in a buried river valley, offshore Burdekin Delta, northeastern Australia
http://espace.library.uq.edu.au/view/UQ:95221
20070823T23:30:40Z
Fielding, C. R.; Trueman, J.; Dickens, G. R.; Page, M.

Anatomy of sealevel change over the last glacial cycle as preserved in a buried river valley, offshore Burdekin delta, northeastern Australia
http://espace.library.uq.edu.au/view/UQ:95352
20070823T23:36:43Z
Fielding, C. R.; Trueman, J.; Dickens, G. R.; Page, M

An equivalent algorithm for simulating thermal effects of magma intrusion problems in porous rocks
http://espace.library.uq.edu.au/view/UQ:39472
An equivalent algorithm is proposed to simulate thermal effects of the magma intrusion in geological systems, which are composed of porous rocks. Based on the physical and mathematical equivalence, the original magma solidification problem with a moving boundary between the rock and intruded magma is transformed into a new problem without the moving boundary but with a physically equivalent heat source. From the analysis of an ideal solidification model, the physically equivalent heat source has been determined in this paper. The major advantage in using the proposed equivalent algorithm is that the fixed finite element mesh with a variable integration time step can be employed to simulate the thermal effect of the intruded magma solidification using the conventional finite element method. The related numerical results have demonstrated the correctness and usefulness of the proposed equivalent algorithm for simulating the thermal effect of the intruded magma solidification in geological systems. (C) 2003 Elsevier B.V. All rights reserved.
20070813T13:43:55Z
Zhao, CB; Hobbs, BE; Ord, A; Lin, G; Muhlhaus, HB

A new 3D simulation framework to model blast induced rock mass displacement using physics engines
http://espace.library.uq.edu.au/view/UQ:197804
20100304T16:08:35Z
Tordoir, A.; Weatherley, D.; Onederra, I.; Bye, A.