http://espace.library.uq.edu.au/ The University of Queensland en Fez http://blogs.law.harvard.edu/tech/rss http://espace.library.uq.edu.au/view/UQ:142330 2008-06-10T13:23:25Z Huang, L. og Mora, P. R. og Fehler, M. http://espace.library.uq.edu.au/view/UQ:150855 2008-06-06T16:50:16Z Mora, P. R. og Place, D. G. http://espace.library.uq.edu.au/view/UQ:67270 2007-08-15T02:36:08Z Weatherley, D. K. og Mora, P. R. 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 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 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 long-range stress correlations. A constant rate of activity is associated with a decorrelated stress field. 2007-08-15T05:12:20Z Weatherley, D og Mora, P http://espace.library.uq.edu.au/view/UQ:142328 2008-06-10T13:23:19Z Jaume, S. C. og Weatherley, D. K. og Mora, P. R. 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 self-organized critical (SOC) behavior (PSD model) and the other which produces quasi-periodic 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 moderate-sized events. On average, no increase in the rate of events of any size is seen before large events in the PSD model. 2007-08-13T12:10:20Z Jaume, SC og Weatherley, D og Mora, P http://espace.library.uq.edu.au/view/UQ:150845 2008-06-06T16:49:52Z Jaume, S. C. og Mora, P. R. og Bufe, C. G. http://espace.library.uq.edu.au/view/UQ:150877 2008-06-06T16:51:10Z Winter, M. http://espace.library.uq.edu.au/view/UQ:149059 2008-06-06T15:09:27Z Weatherley, D. K. og Mora, P. R. http://espace.library.uq.edu.au/view/UQ:61053 2007-08-14T16:56:51Z Jaume, S. C. og Weatherley, D. K. og Mora, P. R. 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. 2007-08-15T06:03:39Z Mora, P og Muhlhaus, H og Gross, L og Xing, H og Weatherley, D og Abe, S og Latham, S og Moresi, L 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 point-searching algorithm for solution interpolation in unstructured meshes consisting of 4-node bilinear quadrilateral elements is presented in this paper. The proposed algorithm has the following significant advantages: (1) The use of a point-searching 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 four-node 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 point-searching algorithm. Copyright (C) 1999 John Wiley & Sons, Ltd. 2007-08-13T11:14:51Z Zhao, CB og Hobbs, BE og Muhlhaus, HB og Ord, A 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. 2007-08-13T16:51:05Z Sulem, J og Muhlhaus, HB http://espace.library.uq.edu.au/view/UQ:103214 2007-08-23T21:26:13Z Xing, H. og Mora, P. R. http://espace.library.uq.edu.au/view/UQ:103209 2007-08-23T21:26:03Z Mora, P. R. og Saez, E. og Weatherley, D. K. og Gross, L. og Wang, C. M. http://espace.library.uq.edu.au/view/UQ:38323 A model for finely layered visco-elastic 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 C-1 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 normal-to 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. 2007-08-13T13:03:04Z Muhlhaus, HB og Dufour, F og Moresi, L og Hobbs, B 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 elasto-dynamic 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 multi-fault simulation examples are presented using a nonlinear frictional relation that is slip and slip-rate dependent in order to illustrate the model. 2007-08-13T13:44:47Z Mora, P. R. og Weatherley, D. K. http://espace.library.uq.edu.au/view/UQ:150860 2008-06-06T16:50:29Z Mora, P. R. og Place, D. G. og Jaume, S. C. og Abe, S. http://espace.library.uq.edu.au/view/UQ:96782 2007-08-24T00:47:59Z Mora, P. R. og Place, D. G. http://espace.library.uq.edu.au/view/UQ:101595 2007-08-23T20:16:35Z Saez, E. og Mora, P. R. og Gross, L. og Weatherley, D. K. 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 in-house 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. 2008-02-18T14:48:43Z Xing, H. L. og Zhang, J. og Yin, C. http://espace.library.uq.edu.au/view/UQ:101686 2007-08-23T20:20:17Z Saez, E. og Mora, P. R. og Gross, L. og Weatherley, D. K. http://espace.library.uq.edu.au/view/UQ:101685 2007-08-23T20:20:16Z Davies, M. og Gerschwitz, J. C. og Gross, L. 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. 2006-03-24T00:00:00Z Moresi, Louis N. og Dufour, Frederic og Muhlhaus, Hans http://espace.library.uq.edu.au/view/UQ:150867 2008-06-06T16:50:45Z Place, D. G. og Mora, P. R. 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 solid-like behavior of the lithosphere by only considering a purely fluid description. However, over the past 5 years, a more self-consistent 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 large-scale 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 high-resolution in three-dimensions, 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 "S-bend" trench curvature previously observed in similar models. While reproducing this emergent feature validates that the lithosphere-mantle 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. 2009-04-08T20:21:30Z OzBench, Mark og Regenauer-Lieb, Klaus og Stegman, Dave R. og Morra, Gabriele og Farrington, Rebecca og Hale, Alina og May, David, A. og Freeman, Justin og Bourgouin, Laurent og Muhlhaus, Hans og Moresi, Louis http://espace.library.uq.edu.au/view/UQ:35057 A theoretical analysis is carried out to investigate the pore-fluid pressure gradient and effective vertical-stress 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 Fore-fluid 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 pore-fluid pressure gradient or the intrinsic effective vertical-stress gradient can be maintained at the value of the lithostatic pressure gradient. Even though the intrinsic pore-fluid 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 vertical-stress 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. 2007-08-13T10:35:14Z Zhao, CB og Hobbs, BE og Muhlhaus, HB 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 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 with more strongly slip-weakening frictional laws, and the degree of slip-weakening 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 elasto-plastic constitutive law for the interface friction at the fault is formulated based on the Coulomb failure criterion and applied in a way analogous to non-associated elasto-plasticity. We provide benchmark tests of our method against other reported solutions in the literature. We demonstrate the applicability of our elasto-plastic fault model for modeling dynamic rupture and wave propagation in fault systems, and the rich array of dynamic properties produced by our elasto-plastic 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. 2007-10-24T12:30:05Z Olsen-Kettle, Louise og Weatherley, Dion og Saez, Estelle og Gross, Lutz og Muhlhaus, Hans og Xing, Huilin http://espace.library.uq.edu.au/view/UQ:174782 2009-04-08T20:12:28Z Kettle, Louise M. og Weatherley, Dion K. og Saez, Estelle og Gross, Lutz og Muhlhaus, Hans B. og Xing, Huilin http://espace.library.uq.edu.au/view/UQ:38712 We conduct a theoretical analysis of steady-state heat transfer problems through mid-crustal 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 pore-fluid 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 pore-fluid 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. 2007-08-13T13:16:39Z Zhao, CB og Hobbs, BE og Muhlhaus, HB og Ord, A og Lin, G http://espace.library.uq.edu.au/view/UQ:139060 2008-06-02T17:20:57Z Xu, H. og Xing, H. og Wyborn, D. og Mora, P. R. http://espace.library.uq.edu.au/view/UQ:124055 Exact analytical solutions have been derived rigorously for the pore-fluid velocity, pore-fluid-flow focusing factor, stream function and excess pore-fluid pressure around and within a buried inclined elliptic inclusion in pore-fluid-saturated 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 pore-fluid-flow 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 pore-fluid-flow 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 pore-fluid-flow focusing problem. The pore-fluid-flow focusing factor of a buried elliptic inclusion is demonstrated to be dependent on the aspect ratio, the permeability ratio and the dip angle. 2008-01-25T18:02:03Z Zhao, CB og Hobbs, BE og Ord, A og Peng, SL og Liu, LM og Muhlhaus, HB http://espace.library.uq.edu.au/view/UQ:95221 2007-08-23T23:30:40Z Fielding, C. R. og Trueman, J. og Dickens, G. R. og Page, M. http://espace.library.uq.edu.au/view/UQ:95352 2007-08-23T23:36:43Z Fielding, C. R. og Trueman, J. og Dickens, G. R. og Page, M 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. 2007-08-13T13:43:55Z Zhao, CB og Hobbs, BE og Ord, A og Lin, G og Muhlhaus, HB http://espace.library.uq.edu.au/view/UQ:174778 2009-04-08T19:53:43Z Wang, Yucang http://espace.library.uq.edu.au/view/UQ:174781 In this paper we advance the development of our python-based package for the solution of partial differential equations using spatial discretization techniques such as the finite element method (FEM) via two approaches. First we define a Model class object which makes it easy to break down a complex simulation into simpler sub-models, which then can be linked together into a highly efficient whole. Second, we implement an XML schema in which we can save an entire simulation. This allows implemention of check-pointing in addition to graphical user interfaces which enables non-programmers to use models developed for their research. These features are built upon our escript module, a software package designed to develop numerical models in a very abstract way while still allowing the use of computational components implemented in C and C++ to achieve extreme high-performance for time-intensive calculations. 2009-04-08T20:07:30Z Gross, Lutz og Muhlhaus, Hans og Thorne, Elspeth og Steube, Ken http://espace.library.uq.edu.au/view/UQ:95095 2007-08-23T23:21:36Z Fielding, C. R. og Sliwa, R. og Holcombe, R. J. og Jones, A. T. http://espace.library.uq.edu.au/view/UQ:39498 The paper presents a theory for modeling flow in anisotropic, viscous rock. This theory has originally been developed for the simulation of large deformation processes including the folding and kinking of multi-layered visco-elastic rock (Muhlhaus et al. [1,2]). The orientation of slip planes in the context of crystallographic slip is determined by the normal vector - the director - of these surfaces. The model is applied to simulate anisotropic mantle convection. We compare the evolution of flow patterns, Nusselt number and director orientations for isotropic and anisotropic rheologies. In the simulations we utilize two different finite element methodologies: The Lagrangian Integration Point Method Moresi et al [8] and an Eulerian formulation, which we implemented into the finite element based pde solver Fastflo (www.cmis.csiro.au/Fastflo/). The reason for utilizing two different finite element codes was firstly to study the influence of an anisotropic power law rheology which currently is not implemented into the Lagrangian Integration point scheme [8] and secondly to study the numerical performance of Eulerian (Fastflo)- and Lagrangian integration schemes [8]. It turned out that whereas in the Lagrangian method the Nusselt number vs time plot reached only a quasi steady state where the Nusselt number oscillates around a steady state value the Eulerian scheme reaches exact steady states and produces a high degree of alignment (director orientation locally orthogonal to velocity vector almost everywhere in the computational domain). In the simulations emergent anisotropy was strongest in terms of modulus contrast in the up and down-welling plumes. Mechanisms for anisotropic material behavior in the mantle dynamics context are discussed by Christensen [3]. The dominant mineral phases in the mantle generally do not exhibit strong elastic anisotropy but they still may be oriented by the convective flow. Thus viscous anisotropy (the main focus of this paper) may or may not correlate with elastic or seismic anisotropy. 2007-08-13T13:44:46Z Muhlhaus, H. B. og Cada, M. og Moresi, L. http://espace.library.uq.edu.au/view/UQ:83407 We have developed a way to represent Mohr-Coulomb failure within a mantle-convection fluid dynamics code. We use a viscous model of deformation with an orthotropic viscoplasticity (a different viscosity is used for pure shear to that used for simple shear) to define a prefered plane for slip to occur given the local stress field. The simple-shear viscosity and the deformation can then be iterated to ensure that the yield criterion is always satisfied. We again assume the Boussinesq approximation, neglecting any effect of dilatancy on the stress field. An additional criterion is required to ensure that deformation occurs along the plane aligned with maximum shear strain-rate rather than the perpendicular plane, which is formally equivalent in any symmetric formulation. We also allow for strain-weakening of the material. The material can remember both the accumulated failure history and the direction of failure. We have included this capacity in a Lagrangian-integration-point finite element code and show a number of examples of extension and compression of a crustal block with a Mohr-Coulomb failure criterion. The formulation itself is general and applies to 2- and 3-dimensional problems. 2007-08-15T11:00:25Z Moresi, L. og Muhlhaus, H. B. http://espace.library.uq.edu.au/view/UQ:99910 2007-08-24T13:02:03Z Muhlhaus, H. B. og Moresi, L. og Cada, M. http://espace.library.uq.edu.au/view/UQ:74319 2007-08-15T05:09:42Z Pasternak, E. og Muhlhaus, H. B. og Dyskin, A. http://espace.library.uq.edu.au/view/UQ:139059 2008-06-02T16:57:27Z Xing, Huilin og Zhang, J. http://espace.library.uq.edu.au/view/UQ:37508 The occurrence of foliated rock masses is common in mining environment. Methods employing continuum approximation in describing the deformation of such rock masses possess a clear advantage over methods where each rock layer and each inter-layer interface (joint) is explicitly modelled. In devising such a continuum model it is imperative that moment (couple) stresses and internal rotations associated with the bending of the rock layers be properly incorporated in the model formulation. Such an approach will lead to a Cosserat-type theory. In the present model, the behaviour of the intact rock layer is assumed to be linearly elastic and the joints are assumed to be elastic-perfectly plastic. Condition of slip at the interfaces are determined by a Mohr-Coulomb criterion with tension cut off at zero normal stress. The theory is valid for large deformations. The model is incorporated into the finite element program AFENA and validated against an analytical solution of elementary buckling problems of a layered medium under gravity loading. A design chart suitable for assessing the stability of slopes in foliated rock masses against flexural buckling failure has been developed. The design chart is easy to use and provides a quick estimate of critical loading factors for slopes in foliated rock masses. It is shown that the model based on Euler's buckling theory as proposed by Cavers (Rock Mechanics and Rock Engineering 1981; 14:87-104) substantially overestimates the critical heights for a vertical slope and underestimates the same for sub-vertical slopes. Copyright (C) 2001 John Wiley & Sons, Ltd. 2007-08-13T12:29:09Z Adhikary, DP og Muhlhaus, HB og Dyskin, AV http://espace.library.uq.edu.au/view/UQ:35639 We present a numerical methodology for the study of convective pore-fluid, thermal and mass flow in fluid-saturated porous rock basins. lit particular, we investigate the occurrence and distribution pattern of temperature gradient driven convective pore-fluid flow and hydrocarbon transport in the Australian North West Shelf basin. The related numerical results have demonstrated that: (1) The finite element method combined with the progressive asymptotic approach procedure is a useful tool for dealing with temperature gradient driven pore-fluid flow and mass transport in fluid-saturated hydrothermal basins; (2) Convective pore-fluid flow generally becomes focused in more permeable layers, especially when the layers are thick enough to accommodate the appropriate convective cells; (3) Large dislocation of strata has a significant influence off the distribution patterns of convective pore;fluid flow, thermal flow and hydrocarbon transport in the North West Shelf basin; (4) As a direct consequence of the formation of convective pore-fluid cells, the hydrocarbon concentration is highly localized in the range bounded by two major faults in the basin. 2007-08-13T11:12:37Z Zhao, CB og Hobbs, BE og Baxter, K og Muhlhaus, HB og Ord, A http://espace.library.uq.edu.au/view/UQ:101654 2007-08-23T20:19:09Z Abe, S. og Mora, P. R. http://espace.library.uq.edu.au/view/UQ:74397 The Lattice Solid Model has been used successfully as a virtual laboratory to simulate fracturing of rocks, the dynamics of faults, earthquakes and gouge processes. However, results from those simulations show that in order to make the next step towards more realistic experiments it will be necessary to use models containing a significantly larger number of particles than current models. Thus, those simulations will require a greatly increased amount of computational resources. Whereas the computing power provided by single processors can be expected to increase according to Moore's law, i.e., to double every 18-24 months, parallel computers can provide significantly larger computing power today. In order to make this computing power available for the simulation of the microphysics of earthquakes, a parallel version of the Lattice Solid Model has been implemented. Benchmarks using large models with several millions of particles have shown that the parallel implementation of the Lattice Solid Model can achieve a high parallel-efficiency of about 80% for large numbers of processors on different computer architectures. 2007-08-15T05:12:30Z Abe, Steffen og Place, David og Mora, Peter http://espace.library.uq.edu.au/view/UQ:94173 2007-08-22T10:16:47Z http://espace.library.uq.edu.au/view/UQ:146009 2008-06-06T11:15:44Z http://espace.library.uq.edu.au/view/UQ:67681 2007-08-15T02:50:51Z Pasternak, E. og Muhlhaus, H. B. og Dyskin, A.