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Duran A.,Pells Sullivan Meynink
Australian Geomechanics Journal | Year: 2012

A study has been undertaken to confirm appropriate analysis methods applicable to design of granular waste materials and specifically that of "spoil piles" for open pit coal mining. The authors' experience with spoil pile stability is that the critical failure mechanism is a two wedge mechanism in accord with that highlighted in the literature. Analysis requires careful consideration of the combination of spoil shear strengths and the angle of the "rear" scarp adopted. Moreover, the literature indicates analyses need to take account of the inclined "inter-slice" within the mechanism. To highlight these considerations an example case was assessed utilising five limit equilibrium stability packages, two "numerical based" packages and a spreadsheet developed by the author. Several analyses are based on vertical slices to pose the question: what is the magnitude of error not using an inclined "inter-slice"? The results are presented as overall spoil pile angle indicated by the use of different software, stability method and assumptions on inclination of "rear" scarp and inter-slice. The example case highlights that, provided a rigorous stability method is utilised, for a given rear scarp assumption, the results of the analyses are insensitive to the software utilised. Therefore with appropriate judgement assessment of spoil pile stability should not be predicated by use of one particular software or stability method. Source

Pournaghiazar M.,Pells Sullivan Meynink | Russell A.R.,University of New South Wales | Khalili N.,University of New South Wales
Applied Mechanics and Materials | Year: 2014

The problem of drained cavity expansion in a soil of finite radial extent is investigated. Spherical cavities expanded from zero radius subjected to a constant stress condition at the finite boundary are considered. The new analytical solution procedure presented enables more advanced constitutive models to be implemented than possible than when using other solution procedures. Cavity expansion results generated for a Sydney quartz sand highlight substantial differences between cavity limit pressures for boundaries of finite and infinite radial extent. © (2014) Trans Tech Publications, Switzerland. Source

Estrada B.,Pells Sullivan Meynink | Estrada B.,University of Western Australia
Bulletin of Engineering Geology and the Environment | Year: 2014

Some features in the landscape are the direct result of earthquake and tectonic deformation. The recognition and analysis of these geomorphological features allows the identification of regions subjected to past earthquake activity or tectonic deformation, which can be directly applied in many areas of engineering geology. However, some regions lack evident geomorphological features despite being subjected to recurrent earthquakes and/or ongoing tectonism. Drainage networks are very sensitive to changes along their flow path, so the characteristics of the drainage can be used to infer areas with "hidden" evidence of past earthquake activity or tectonic deformation. Two examples from contrasting tectonic environments (i.e., Australia and New Zealand) are used to illustrate the application and effectiveness of drainage analysis. © 2014 Springer-Verlag Berlin Heidelberg. Source

Meynink W.J.C.,Mine Water Specialists Int. Pty Ltd. | Rogan A.,Pells Sullivan Meynink
The Art and Science of Water - 36th Hydrology and Water Resources Symposium, HWRS 2015 | Year: 2015

Many aspects of mine closure design require estimates of quantities, rates and pathways of runoff from disturbed areas. Using rehabilitant farmland as the analogue, Burrows (1990) suggest it may take 200-300 years for forest vegetation to adjust to dramatic change. Accordingly, gauged, naturally vegetated catchments might be considered equilibrated in terms of climate, vegetation, regolith and topography after 200-300 years if climate and in particular rainfall has been stationary. In as much as sea level defines macro scale climate change it is noted it is about 7000 years since the last major sea level change. As such gauged, naturally vegetated catchments are reasonable analogues for hydrologically similar ungauged ones. For mine surfaces, and spoil dumps in particular, not only is there a dearth of data generally but any data is just a snapshot in time in the evolution of the dump with varying consolidation, weathering, wetting up and vegetative progression, the latter having a time scale of tens to hundreds of years. Each of these processes introducing another layer of uncertainty. From a statistical predictive reliability perspective, if natural catchments require simple models, then spoil dumps require even simpler models. This is a conundrum for engineering hydrologists since extra parameterisation to capture the unsteady and evolving nature of spoil dumps seems, with a conventional bottom up water balance modelling approach, unavoidable. This study adopts Eagleson's (1982, 2002) notion that climate is the primary determinant of vegetation type and density and develops a parsimonious model applicable to variable 'surface' mine sites. Using a specific definition of evaporative potential and a single user prescribed parameter, yield and gradient are defined by a modified Pike algorithm for each sub-catchment or surface. Using a long historic or synthetic daily rainfall series this yield is disaggregated to daily rainfall excess so as to match the Pike algorithm yield and gradient. In turn daily rainfall excess is partitioned into surface and deep percolation runoff using an existing, simple, two parameter hillslope baseflow model. For any mine site 'surface' just one parameter is required to define runoff volumes and an additional two to define rates and pathways. © 2015, Engineers Australia. All rights reserved. Source

Rogan A.,Pells Sullivan Meynink | Meynink B.,Mine Water Specialists International
The Art and Science of Water - 36th Hydrology and Water Resources Symposium, HWRS 2015 | Year: 2015

Accurate estimation of evaporation from a spilling 4 km2 shallow lake (Lake Namuk) on the equator in Kalimantan, Indonesia, was required to allow assessment of 1,000 year design drought water levels. Eight square kilometres of perennial contributing peripheral catchments prevented direct measurement of lake evaporation in the 3,860 mm/a rainfall environment. Few examples of climate parameter based estimates of evaporation could be found in literature generally for equatorial areas or for Kalimantan in particular. The climate at the lake was measured by an automatic weather station with: pyranometer (short wave solar radiation), wind speed (2 and 10 m), dew point temperature, air temperature, rainfall and water temperature near surface and at one metre depth. Lake Namuk has a surface water temperature consistently higher (∼3.2°C) than the ambient temperature. Several combination method algorithms and the equilibrium temperature method of Edinger et al (1974) were applied to estimate evaporation with observed water surface (equilibrium) temperatures used firstly for testing the algorithms and then wind function calibration. The minimal variations in seasonal temperatures allowed surface temperatures to be used as a proxy for equilibrium temperatures. This process demonstrated the need for back radiation estimates to be based on the surface rather than ambient temperature. Methods based on ambient temperature gave a 0.5 mm/day over-estimation of evaporation. A wind function that considered both convective and turbulent mixing processes was developed for the low wind environment. Once incorporated all algorithms produced similar evaporation estimates, in turn consistent with the limited available regional pan data. © 2015, Engineers Australia. All rights reserved. Source

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