Random finite element method prediction and optimisation for open pit mine slope stability analysis

Inherent soil variability can have significant effects on the stability of open-pit mine slopes. In practice, the spatial variability of materials is not commonly considered as a routine component of slope stability analysis. The process of quantifying spatially variable parameters, as well as the modelling of their behaviour is often a complex undertaking. Currently, there are no large-scale commercial software packages containing in-built methods for modelling spatial variability within the Finite Element environment. Furthermore, conventional Limit Equilibrium Methods (LEM) incorporating spatial variability are unable to consider the stress/strain characteristics of these materials. The following research seeks to accurately model the slope mechanics of spatially variable soils, adopting The Random Finite Element Method (RFEM) developed by Griffiths and Fenton (2004) to determine slope failure mechanisms and safety factors. Techniques are developed to produce a set of optimised Random Finite Element Method simulations using the Monte Carlo Method. Additionally, random field analysis techniques are investigated to compare and categorise soil parameter fluctuation, providing a direct relationship between random field properties and slope failure surfaces. Optimisation and analysis techniques are implemented to examine the effects of cross-sectional geometries and input parameter distributions on failure mechanisms, safety factors and probabilities of failure. Cross-sectional RFEM analysis is performed in the Finite Element Method (FEM) software package Abaqus, with the techniques of this research demonstrated for a large open-pit brown coal mine located in the state of Victoria, Australia. The outcome of this research is a comprehensive procedure for optimised RFEM simulation and analysis.Doctor of Philosoph

Inspection of open-pit mine drainage characteristics with a horizontal borehole camera

Horizontal bores and drains are crucial infrastructures for maintaining the stability of large open-pit mines. Induced deformations as the result of mining activities and the infiltration of water from large surface catchments during heavy rain events can cause the build-up of pore water pressures in brown coal batters. This can potentially lead to catastrophic slope failures. Horizontal boreholes and drains are commonly installed at shallow inclines and typically range in length from 150 to 400 metres. Due to complexities in surveying lengthy horizontal bores, the long-term internal properties of these structures are poorly understood. In this research, a specialised horizontal borehole camera was developed to observe a range of factors influencing borehole performance including the identification of fractured or jointed material, borehole geometry and features, and locationally dependent water outflow and drainage paths. Investigations were undertaken at an operational brown coal mine in the Latrobe Valley, located in Victoria, Australia. Features observed on the profile of horizontal bores are discussed, with an emphasis on providing in-situ material characterisation and for the purposes of maintaining stable mine batters. © Published under licence by IOP Publishing Ltd

Action research in physical education: focusing beyond myself through cooperative learning

This paper reports on the pedagogical changes that I experienced as a teacher engaged in an action research project in which I designed and implemented an indirect, developmentally appropriate and child‐centred approach to my teaching. There have been repeated calls to expunge – or at least rationalise – the use of traditional, teacher‐led practice in physical education. Yet despite the advocacy of many leading academics there is little evidence that such a change of approach is occurring. In my role as teacher‐as‐researcher I sought to implement a new pedagogical approach, in the form of cooperative learning, and bring about a positive change in the form of enhanced pupil learning. Data collection included a reflective journal, post‐teaching reflective analysis, pupil questionnaires, student interviews, document analysis, and non‐participant observations. The research team analysed the data using inductive analysis and constant comparison. Six themes emerged from the data: teaching and learning, reflections on cooperation, performance, time, teacher change, and social interaction. The paper argues that cooperative learning allowed me to place social and academic learning goals on an even footing, which in turn placed a focus on pupils’ understanding and improvement of skills in athletics alongside their interpersonal development

Model fidelity and students’ responses to an authenticated unit of Cooperative Learning

A wealth of school-based interventions report on students’ positive responses to the use of models-based practice in physical education. However, research that examines the effectiveness of models-based practice rarely reports on the fidelity of implementation i.e. when all of the characteristics of a model are implemented. The purpose of this study was to explore model fidelity in the use of the Cooperative Learning model. Action research and systematic observation (using the Cooperative Learning Validation Tool which acknowledged the key characteristics of the model) were used to confirm model fidelity. Consequently, the themes of ‘scaffolding student learning', 'working together', and 'deeper learning' could be directly linked to the authentic use of Cooperative Learning context. The paper concludes by arguing that when reporting on findings from empirical research on the use of Cooperative Learning we need to adopt a more robust approach in determining – through rigor and quality of research – the authenticity of implementation

Coupled Eulerian-Lagrangian Debris Flow Model with Flexible Barrier

Natural hazards such as large debris flow events can have catastrophic effects on the environment and critical infrastructure, posing a significant threat to human life. Debris flows often exhibit high velocity, high-pressure discharges due to their bulk volume, and the capacity to transport considerable volumes of large rocks, boulders, and woody debris. Although debris flow run-out simulations are commonly performed using hydraulic modelling software, these environments are seldom capable of assessing the interaction between the debris fluid, transported material, and protective structures. In this research, large deformation numerical models are calibrated using input parameters from hydraulic modelling software. Due to the computational cost of the large deformation models involving fluid-solid-structure simulation with flexible net barriers, an equivalent stiffness method is implemented to provide comparable performance through a membrane structure. The Coupled Eulerian-Lagrangian Finite Element method is used to model the impact forces of rocky boulders on the membrane, exhibiting damage characteristics consistent with flexible ring-net protective structures. The Coupled Eulerian-Lagrangian model results highlight the performance of the simplified membrane, as shown through a benchmark simulation of debris flow with boulders

Spatially Variable Coal Slope Stability Analysis using Image-Based Scaled Boundary Finite Element Method

Slope stability analysis is a challenging task when complex stratigraphies, complex geometries and spatially variably soil parameters are considered. Numerical methods, such as the finite element method are commonly used in slope stability analyses, however, these methods require significant user input when meshing geometries consisting of heterogeneous and spatially variable materials. This paper presents a numerical technique combining the scaled boundary finite element method and image-based meshing for slope stability analysis. The inputs for the analyses require images detailing the stratigraphy and the spatial variation of the material properties. Quadtree decomposition is applied to simultaneously generate meshes and consider the spatial variation of material properties directly from the images through a mapping technique. The stability of slopes is analysed assuming an elastoplastic Mohr-Coulomb constitutive model for the soil. The shear strength reduction technique is applied to evaluate the shear reduction factor iteratively to define the factor of safety of the slope. Coal slopes at Yallourn open-pit mine, Victoria, Australia was considered, forming the basis of a case study to demonstrate the applicability of the presented method

Cohort study of the impact of direct acting antiviral therapy in patients with chronic hepatitis C and decompensated cirrhosis

Background and Aims: All oral direct-acting antivirals (DAAs) effectively treat chronic hepatitis C virus (HCV) infection, but the benefits in advanced liver disease are unclear. We compared outcomes in treated and untreated patients with decompensated cirrhosis. Methods: Patients with HCV and decompensated cirrhosis or at risk of irreversible disease were treated in an Expanded Access Programme (EAP) in 2014. Treatment, by clinician choice, was with sofosbuvir, ledipasvir or daclatasvir, with or without ribavirin. For functional outcome comparison, untreated patients with HCV and decompensated cirrhosis who were registered on a database 6 months before treatment was available were retrospectively studied. Primary endpoint was sustained virological response 12 weeks post antiviral treatment (treated cohort) and the secondary endpoint (both cohorts) was adverse outcomes (worsening in MELD score or serious adverse event) within 6 months. Results: 467 patients received treatment (409 decompensated cirrhosis). Viral clearance was achieved in 381 patients (81.6%) – 209 from 231 (90.5%) with genotype 1 and 132 from 192 (68.8%) with genotype 3. MELD scores improved in treated patients (mean change -0.85) but worsened in untreated patients (mean + 0.75) (p65 or with low (<135 mmol/L) baseline serum sodium concentrations were least likely to benefit from therapy. Conclusions: All oral DAAs effectively cured HCV in patients with advanced liver disease. Viral clearance was associated with improvement in liver function within 6 months compared to untreated patients. The longer term impact of HCV treatment in patients with decompensated cirrhosis remains to be determined

Synthesis, structures and coordination chemistry of singly bridged phosphane-boranes with coordinately unsaturated platinum group metals

A range of singly bridged phosphane-boranes (PBs) have been investigated as potential ligands for basic transition metals. The PBs Ph2PC(Ph)=C(R)BR2 (R = Bu 1, Ph 2, Et 3), based on a rigid cis-ethylene bridges, have been prepared, improving upon limited literature precedent. All three compounds have been comprehensively characterised for the first time, including by X-ray diffraction studies. Significant intramolecular P→B association is apparent in each case, which serves to preclude their engagement as ligands. In contrast, the more flexible PBs R2P(CH2)2BBN (R = Fu 5, Ph 6) readily coordinate to the platinum group metals Pt, Pd and Rh. These complexes have been fully characterised, including an X-ray diffraction study of [Rh(CO){Fu2P(CH2)2-BBN}2Cl] (13)

Search for Gravitational Waves Associated with 39 Gamma-Ray Bursts Using Data from the Second, Third, and Fourth LIGO Runs

We present the results of a search for short-duration gravitational-wave bursts associated with 39 gamma-ray bursts (GRBs) detected by gamma-ray satellite experiments during LIGO's S2, S3, and S4 science runs. The search involves calculating the crosscorrelation between two interferometer data streams surrounding the GRB trigger time. We search for associated gravitational radiation from single GRBs, and also apply statistical tests to search for a gravitational-wave signature associated with the whole sample. For the sample examined, we find no evidence for the association of gravitational radiation with GRBs, either on a single-GRB basis or on a statistical basis. Simulating gravitational-wave bursts with sine-gaussian waveforms, we set upper limits on the root-sum-square of the gravitational-wave strain amplitude of such waveforms at the times of the GRB triggers. We also demonstrate how a sample of several GRBs can be used collectively to set constraints on population models. The small number of GRBs and the significant change in sensitivity of the detectors over the three runs, however, limits the usefulness of a population study for the S2, S3, and S4 runs. Finally, we discuss prospects for the search sensitivity for the ongoing S5 run, and beyond for the next generation of detectors.Comment: 24 pages, 10 figures, 14 tables; minor changes to text and Fig. 2; accepted by Phys. Rev.

Land reclamation and artificial islands: Walking the tightrope between development and conservation

Coastal developments worldwide have put entire shoreline ecosystems at risk. Recently, land reclamation has been extended to the construction of whole new islands; a phenomenon that is particularly common in Asia and the Middle East and is recognised as a global conservation issue. Using Penang Island, Malaysia as a case study, we illustrate the relationship between rapid population growth and the simultaneous increase in urbanisation, land reclamation and extent of artificial shorelines; and decrease in the quality and extent of natural coastal habitats. Our goal was to provide an up-to-date assessment of the state of coastal habitats around Penang, identify knowledge gaps and identify locations that may be potentially suitable for eco-engineering. Comparisons of historical and current topographic maps revealed that land formerly consisting of coastal swamp and forest, mangrove forests, sandy beaches, and rubber and oil plantations have been lost to large-scale land reclamation and urbanisation. Between 1960 and 2015, there were increases in urbanised area, reclaimed land, and artificial shoreline extent. The total extent of mangrove forests has remained relatively stable but this balance is characterised by significant losses on the east coast coupled with increases on the west coast. Coastal development on the island is still on-going with plans for the construction of five artificial islands and another two coastal reclamation projects are either underway or scheduled for the near future. If the plans for future land reclamations are fully realized, 32.3 km2 of the 321.8 km2 island (10%) will be reclaimed land and the associated negative effects on the island’s natural coastal habitats will be inevitable. This study highlights sections of the coast of Penang Island in need of effective monitoring, conservation and management and explores the possibility of incorporating ecological engineering into development projects, either prospectively or retrospectively, to create more environmentally-friendly urban environments and to promote educational, amenity and economic activities. With coastal development taking place on a global scale, opportunities to balance development needs with conservation strategies abound and should be integrated into present and subsequent projects to protect these coastal ecosystems for future generations