Pathirage U.,University of Wollongong |
Indraratna B.,University of Wollongong |
McIntosh G.,Douglas Partners Pty Ltd. |
Banasiak L.,University of Wollongong
Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014 | Year: 2015
Progress in the remediation of acidic groundwater generated from acid sulfate soil was achieved through the utilisation of an innovative geotechnical engineering technique, namely the installation of an alkaline Permeable Reactive Barrier (PRB) using recycled concrete particles as the reactive material in the Shoalhaven Floodplain, southeast New South Wales (NSW), Australia. The performance of the PRB has been monitored since its installation in October 2006 and it has proved effective in neutralising groundwater from ∼pH 3 to 7.3 and removing ∼95% of Al and Fe from the groundwater.A key outcome of this study was to develop an original model capturing geochemical reaction kinetics coupled with transient groundwater flows, supported by detailed laboratory and field testing. The model could predict the porosity and hydraulic conductivity due to secondary mineral precipitation. The hydraulic conductivity reduction in the field is only 3%at the entrance face and almost negligible in the middle and exit zones to date. © 2015 Taylor & Francis Group, London.
Heitor A.,University of Wollongong |
Indraratna B.,University of Wollongong |
Kaliboullah C.I.,University of Wollongong |
Rujikiatkamjorn C.,University of Wollongong |
McIntosh G.W.,Douglas Partners Pty Ltd.
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2016
Coal wash is a granular waste material that is readily available in the vicinity of coal mining operations. While its potential use in structural fills has been recognized in the past, the effects of particle breakage on the geomechanical performance of the material have not been thoroughly investigated. In this paper, an experimental study on a selected coal wash is undertaken to characterize the influence of compaction and particle breakage on its corresponding stress-strain behavior. Particular emphasis is given to the role of compaction energy level and associated breakage incurred during compaction on the drained and undrained shearing behavior. The incidence of particle breakage for undrained and drained shearing was observed to be different, which in turn had a strong influence in the yielding behavior and the critical state. Furthermore, the critical state conditions for coal wash seem to be better described through a three-dimensional surface incorporating the effect of breakage. © 2016 American Society of Civil Engineers.
Jex C.N.,University of New South Wales |
Jex C.N.,Affiliated to the National Center for Groundwater Research and Training |
Mariethoz G.,University of New South Wales |
Mariethoz G.,Affiliated to the National Center for Groundwater Research and Training |
And 11 more authors.
International Journal of Speleology | Year: 2012
Despite the fact that karst regions are recognised as significant groundwater resources, the nature of groundwater flow paths in the unsaturated zone of such fractured rock is at present poorly understood. Many traditional methods for constraining groundwater flow regimes in karst aquifers are focussed on the faster drainage components and are unable to inform on the smaller fracture or matrix-flow components of the system. Caves however, offer a natural inception point to observe both the long term storage and the preferential movement of water through the unsaturated zone of such fractured carbonate rock by monitoring of drip rates of stalactites, soda straws and seepage from fractures/micro fissures that emerge in the cave ceiling. Here we present the largest spatial survey of automated cave drip rate monitoring published to date with the aim of better understanding both karst drip water hydrogeology and the relationship between drip hydrology and surface climate. By the application of cross correlation functions and multi-dimensional scaling, clustered by k-means technique, we demonstrate the nature of the relationships between drip behaviour and initial surface infiltration and similarity amongst the drip rate time series themselves that may be interpreted in terms of flow regimes and cave chamber morphology and lithology.
Markowska M.,Australian Nuclear Science and Technology Organisation |
Markowska M.,University of New South Wales |
Baker A.,University of New South Wales |
Andersen M.S.,University of New South Wales |
And 11 more authors.
Quaternary Science Reviews | Year: 2016
Oxygen isotope ratios in speleothems may be affected by external processes that are independent of climate, such as karst hydrology and kinetic fractionation. Consequently, there has been a shift towards characterising and understanding these processes through cave monitoring studies, particularly focussing on temperate zones where precipitation exceeds evapotranspiration. Here, we investigate oxygen isotope systematics at Wellington Caves in semi-arid, SE Australia, where evapotranspiration exceeds precipitation. We use a novel D2O isotopic tracer in a series of artificial irrigations, supplemented by pre-irrigation data comprised four years of drip monitoring and three years of stable isotope analysis of both drip waters and rainfall. This study reveals that: (1) evaporative processes in the unsaturated zone dominate the isotopic composition of drip waters; (2) significant soil zone 'wetting up' is required to overcome soil moisture deficits in order to achieve infiltration, which is highly dependent on antecedent hydro-climatic conditions; (3) lateral flow, preferential flow and sorption in the soil zone are important in redistributing subsurface zone water; (4) isotopic breakthrough curves suggest clear evidence of piston-flow at some drip sites where an older front of water discharged prior to artificial irrigation water; and (5) water residence times in a shallow vadose zone (<2 m) are highly variable and can exceed six months. Oxygen isotope speleothem records from semi-arid regions are therefore more likely to contain archives of alternating paleo-aridity and paleo-recharge, rather than paleo-rainfall e.g. the amount effect or mean annual. Speleothem-forming drip waters will be dominated by evaporative enrichment, up to ~3‰ in the context of this study, relative to precipitation-weighted mean annual rainfall. The oxygen isotope variability of such coeval records may further be influenced by flow path and storage in the unsaturated zone that is not only drip specific but also influenced by internal cave climatic conditions, which may vary spatially in the cave. © 2015 .
Maqbool S.,Douglas Partners Pty Ltd. |
Lee B.,Douglas Partners Pty Ltd. |
Ims B.,Douglas Partners Pty Ltd.
Australian Geomechanics Journal | Year: 2014
This paper describes the design of embankments and piled foundations for new bridges across Moonee Ponds Creek as part of the Melbourne M80 Upgrade Project. The bridges are part of the eastbound duplication and consist of 7 spans (main carriageway) and 8 spans (auxiliary exit). The maximum approach embankment height relative to the existing ground surface levels is 17 m, which is up to 6.5 m higher than the adjacent embankment. Moonee Ponds Creek transects the Newer Volcanics and Melbourne Mudstone forming an incised valley (Moonee Ponds Creek Valley) filled with Quaternary alluvial deposits. Significant settlement was experienced during the construction of the original embankments in the early 1990s. The specification for the new bridges imposed tight settlement requirements. This challenge was compounded by restricted space between assets and a tight construction time frame. Details of the construction methodology together with the results of settlement monitoring and the monitoring of vibration due to impact rolling and pile driving are presented.
Lee B.C.,Douglas Partners Pty Ltd |
Ims B.W.,Douglas Partners Pty Ltd
Australian Geomechanics Journal | Year: 2015
Widening of Melbourne's M80 Western Ring Road carriageway required a significant vertical rock cut leading to a new fill embankment for the Moonee Ponds Creek crossing. The rock comprised highly fractured and variably weathered Newer Volcanics basalt. Excavation in other sections of the project in similar fractured basalt had led to significant overbreak. For a conventional concrete faced soil nail solution, similar overbreak in this rock cut was considered to create an appreciable budget overrun not only due to the additional volume of concrete required to fill in the overbreak, but also for the additional steel volume in the nails to support the weight of the thicker concrete facing. To overcome this, a combined rock nail and rock mesh retention system was adopted where a composite action provided restraint for both global and local face stability. Detailed assessment was necessary to determine the interaction between the local rock mesh facing support and the global support afforded by the nails and considerable effort was made to develop an installation procedure allowing construction of the system to be undertaken safely and efficiently. The final rock nail/rock mesh solution minimised the amount of steel and concrete required to support the rock giving a more sustainable solution than originally proposed. The construction of the rock cut involved the installation of about 400 rock nails and was completed in 2 months at the end of 2011.