Infrastructure Engineering - Research Publications
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ItemNo Preview AvailableTesting uncertainty in a model of stream bank erosion( 2020-01-01)Sediment and nutrient loads in Australian rivers are a significant management concern. The National Land and Water Audit (2002) identified bank erosion as a major source of sediment, particularly in southern Australian systems. This paper tests a method of incorporating uncertainty into and the up-scaling of a cross-section scale stream bank erosion model. The cross-section scale model is based on an understanding of fluvial erosion and mass failure processes in which fluvial erosion is estimated using an excess shear stress approach while mass failure is estimated using a limit equilibrium analysis at the cross-section scale. Figure 1 shows a schematic of the model. A Monte-Carlo framework is used to propagate input uncertainty to output uncertainty in the model and to scale up to the reach scale. Widely available databases are used to estimate variables for the two model components. A range of spatial information (GIS layers) is used to describe spatial variations in general properties such as soil type and catchment area. These are considered to be relatively well known (compared with cross-section geometry, geotechnical properties of the bank materials, riparian tree density, and hydrologic variables), although spatially coarse. A variety of empirical models and assumptions are used to transform the spatial information into model parameters, which are considered to be relatively poorly known. Two major challenges, which are related, involve incorporating the effects of natural variability along a river reach and estimating the uncertainty in the model inputs and the effect that this has on uncertainty in the model prediction. A Monte Carlo framework is used to achieve this. This involves developing a series of statistical models to predict the erosion model inputs and their (co)variability. A hierarchical approach is used to develop these input models. An attempt is first made to construct a statistical model that predicts each model parameter from available spatial information using multiple regressions. Uncertainty in these parameters is incorporated using the regression error statistics. Where cross-correlations were found to be important, these were incorporated in the generation models. Where it was not possible to develop empirical relationships with available spatial data sets, a suitable parametric distribution is fitted for those input variables for which some data is available. Where no data were available for fitting a distribution, a distribution was assumed with a shape and parameters based on heuristic consideration of the relevant processes. Once both the erosion model and the various input models were established, the Monte Carlo technique was applied. This involves generating sets of the input variables of the model from the respective stochastic input models and the running the erosion model. This allows the probability distribution for the model output to be estimated for a location in the stream network. The model is tested using historical records of plan form change from a 40km reach of the Goulburn River downstream of Eildon Dam in Victoria, Australia. The results obtained from the model are promising; with bank erosion rates being predicted within a factor of two without calibration. A series of sensitivity analyses (detail sensitivity analysis, scenario analysis, and advance sensitivity analysis) were conducted to identify key variables for predicting bank erosion rates using this particular bank erosion model. This suggested that bank angle, bank material physical characteristics, stream bed slope, and the high-flow flow regime (bankfull duration) control the behaviour of the model for loam bank materials.
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ItemTarget Word Masking for Location Metonymy Resolution(International Committee on Computational Linguistics, 2020)
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ItemMacro-element modelling of plate anchor kinematics under cyclic loading in clay(Deep Foundations Institute, 2020)With the recent shift of offshore renewable energy sector towards deeper waters, the use of floating structures anchored to the seabed through mooring lines is becoming an appealing solution. Several researchers have carried out experimental and numerical analyses to assess the behaviour of plate anchors. However, being able to quickly predict the overall anchor behaviour during keying and operational loads is important for design purposes and to assess their field performance; for this purpose, macro-element modelling is a powerful and timeefficient tool which requires minimal computational effort. In that context, this paper expands a non-associative model for plate anchors to account for the effects of cyclic loading. Whereas the effects of pore-pressure generation, consolidation and eventual material de-structuration were neglected and need to be accounted for in future studies, this study shows that the anchor’s capacity decrease occurs not only due to changes in soil conditions, but also to the particular evolution of anchor’s kinematics due to anchor re-orientation during cyclic loading.
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ItemCyclic capacity of plate anchors in loose sand(Deep Foundations Institute, 2020)This paper describes a centrifuge investigation on drained monotonic and cyclic capacity of a plate anchor in dry loose sand. The model rectangular plate anchor was pre-embedded vertically at an embedment depth of 5 times the plate width, and was loaded horizontally at the mudline with monotonic or irregular cyclic loading to failure. The anchor was also instrumented with an accelerometer to investigate the plate rotation or ‘keying’ behaviour. The monotonically and cyclically loaded anchors are found to share similar plate rotation behaviour. Depending on the applied cyclic load magnitude, the anchor produces post-cyclic ultimate capacity that is up to 7% higher than the reference ultimate monotonic capacity. When compared to existing studies using similar plate anchor in dense sand, the plate anchor in loose sand exhibits a lower gain in post-cyclic ultimate capacity relative to the ultimate monotonic capacity, a softer load-displacement response and a higher plate anchor rotation at ultimate capacity.
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ItemRapid penetration of spudcans in sand(Deep Foundation Institute, 2020)The growing pressure for jack-up rigs to relocate during more challenging metocean conditions for offshore wind turbine installation and maintenance has increased the risk of dynamic leg loading during the set down of the spudcan footings into the seabed. To better understand the rapid sand-spudcan interaction, this study presents experimental results of a model spudcan jacked at a range of penetration rates into dry and saturated sand at both 1g and 50g gravitational acceleration. In order to achieve a wide range of consolidation conditions, the sand was saturated using both water and a viscous pore fluid (methocel cellulose ethers) with kinematic viscosity 680 times higher than water in the 50g centrifuge tests. The results indicated up to 120% increase in spudcan penetration resistance due to the dilatancy-induced suction when the consolidation response changes from drained to undrained. This change in spudcan penetration resistance is quantified using a proposed backbone curve framework.
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ItemLearning from concurrent adaptive management in multiple catchments within a large environmental flows program in Australia(WILEY, 2020-05)Abstract Adaptive management is central to improving outcomes of environmental water delivery. The Australian Government's Murray−Darling Basin (MDB) Plan 2012 explicitly states that adaptive management should be applied in the planning, prioritisation and use of environmental water. A Long Term Intervention Monitoring (LTIM) program was established in 2014 to evaluate responses to environmental water delivery for seven Areas within the MDB, with evaluation also undertaken at the Basin scale. Adaptive management at the Area scale was assessed using two approaches: (a) through a reflective exercise undertaken by researchers, water managers and community members and (b) through an independent review and evaluation of the program, where relevant reports were reviewed and managers and researchers involved in the LTIM program were interviewed. Both assessment approaches revealed that the scale of management actions influenced the extent to which learnings were incorporated into subsequent actions. Although there were many examples where learnings within an Area had been used to adaptively manage subsequent environmental water deliveries within that Area, there was inconsistent documentation of the processes for incorporating learnings into decision making. Although this likely limited the sharing of learnings, there were also examples where learnings from one Area had influenced environmental water management in another, suggesting that sharing between concurrent projects can increase learning. The two assessments identified ways to improve and systematically document the adaptive management learnings. With improved processes to increase reflection, documentation and sharing of learnings across projects, there is an opportunity to improve management of environmental water and ecosystem outcomes.
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ItemEffect of anthropogenic heat sources in the shallow subsurface at city-scale(EDP Sciences, 2020-11-18)Rapid rates of urbanisation are placing growing demands on cities for accommodation and transportation, with increasing numbers of basements and tunnel networks being built to meet these rising demands. Such subsurface structures constitute continuous heat sources and sinks, particularly if maintained at comfortable temperatures. At the city-scale, there is limited understanding of the effect of heat exchange of underground infrastructures with their environments, in part due to limited availability of long-term underground temperature data. The effects of underground temperature changes due anthropogenic heat fluxes can be significant, impacting ventilation and cooling costs of underground spaces, efficiency of geo-energy systems, quality and quantity of groundwater flow, and the health and maintenance of underground structures. In this paper we explore the impact of anthropogenic subsurface structures on the thermal climate of the shallow subsurface by developing a heat transfer model of the city of Cardiff, UK, utilising a recently developed semi-3D modelling approach.
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ItemThermal performance of the ground in geothermal pavements(EDP Sciences, 2020-11-18)Shallow geothermal energy utilises the ground at relatively shallow depths as a heat source or sink to efficiently heat and cool buildings. Geothermal pavement systems represent a novel concept where horizontal ground source heat pump systems (GSHP) are implemented in pavements instead of purpose-built trenches, thus reducing their capital costs. This paper presents a geothermal pavement system segment (20m × 10m) constructed and monitored in the city of Adelaide, Australia, as well as thermal response testing (TRT) results. Pipes have been installed in the pavement at 0.5 m depth, and several thermistors have been placed on the pipes and in the ground. A TRT has been performed with 6kW heating load to achieve an understanding of the thermal response of the system as well as to estimate the effective thermal conductivity of the ground. The results show that the conventional semi-log method may be applicable to determine the thermal conductivity for geothermal pavements. The geothermal heat exchanger at shallow depth is considerably under the influence of the ambient temperature; however, it is still acceptable for exchanging the heat within the ground. It is also concluded that the impact radius of heat exchanger in geothermal pavement during the TRT is around 0.5m in the vertical and horizontal directions for this case study.
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ItemThermal response of energy soldier pile walls(EDP Sciences, 2020-11-18)Utilising foundation systems as heat exchangers has received significant public interest worldwide, as these energy geo-structures can constitute a clean, renewable, and economical solution for space heating and cooling. Despite their potential, the thermal performance of energy retaining walls, especially soldier pile walls, has not been sufficiently studied and understood and thus further research is required. This work utilises the first ever energy soldier pile wall in the currently under-construction Melbourne CBD North metro station as a case study. A section of this wall has been instrumented and monitored by the University of Melbourne. Full scale thermal response tests (TRTs) have been conducted on a single thermo-active soldier pile at two different excavation levels. Thermal response testing field data results are presented in terms of mean fluid temperatures and further analysed to show the potential impact of the excavation level on the structure’s thermal performance. To further explore this impact of excavation depth (or pile embedment depth) and the long-term thermal performance of energy pile walls, a detailed 3D finite element numerical model is developed in COMSOL Multiphysics and validated against the field-testing results. The simulation suggests that thermally activating all the soldier piles in the station can provide enough energy to fulfil the heating and cooling demand of the station and to satisfy partial heating demand to the surrounding buildings. Furthermore, results suggest that current energy pile design approaches may be adapted for designing energy pile walls.
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ItemA Multi-Camera Tracker for Monitoring Pedestrians in Enclosed Environments(IEEE, 2020)Multi-camera pedestrians tracking is a challenging computer vision task. We propose a multi-camera tracker for monitoring pedestrians in an enclosed shopping environment. We assess the performance of the multi-camera tracker in a case study, tracking customers in a food and speciality market hall. Our multi-camera tracker tracks customers' walking between the stalls in the market. The information is useful for market management, visitor safety, and other potential application areas.