The journey to a water sensitive city - a case study of Ballarat, Victoria, Australia
- Authors: Ebbs, David , Kandra, Harpreet , Dahlhaus, Peter
- Date: 2016
- Type: Text , Conference paper
- Relation: 37th Hydrology & Water Resources Symposium 2016: Water, Infrastructure and the Environment p. 107-114
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- Description: Water security is a vital part of ensuring a sustainable future. This is particularly true for many cities in Australia where relatively low rainfall, population growth and climate change places communities under water stress. The 'Water Sensitive City' is one in which water is drawn from a range of water supplies and that sustainably interacts with its surrounding environment. Every city has a unique water history in which the economic, environmental and social history have impacted on the development of water management. Tracking the evolution of water management of a city from its initial stages can provide information regarding the journey towards a Water Sensitive City. Water management in Ballarat has been tracked from the establishment of the first water supply to the city in the 1850's until 2015 using historical records from the local water authority. These records show that Ballarat generally followed the classical water development model with the introduction of water supply, sewerage and water treatment. Water use in Ballarat increased dramatically from 1941 until 1980, in line with increased standards of living as expected. However, after this time water use decreased despite continued population growth, and commercial water use decreased as a percentage of total use and external water use also declined. The reasons behind the decline in water use since 1980 may contain lessons that can be used in the establishment of Water Sensitive Cities.
Experimental study of brown coal hydraulic behavior at low confining stress
- Authors: Liu, Kan , Mackay, Rae , Xue, Jianfeng , Tolooiyan, Ali
- Date: 2014
- Type: Text , Conference paper
- Relation: 6th International Conference on Unsaturated Soils p. 1125-1130
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- Description: The hydraulic behavior of Victorian brown coal has been studied under low pressure confining conditions. A triaxial constant head permeameter was constructed to carry out permeability tests under alternative confining conditions. Test results from alternative constant head test methods were found to be different indicating higher than expected internal storage due to the possible existence of gas in the coal matrix and/or compressibility of the coal grains. A conceptual model of brown coal with disconnected gas bubbles was proposed to explain the observed variation of hydraulic behavior. In this model, the compressible gas bubbles are assumed to be trapped between compressible coal particles. A numerical model was developed to gain insights into the hydraulic influence of these factors and the model was used to simulate the test process. Constant hydraulic conductivity was assumed. The results from the model and the tests are found to compare well. The model explains most but not all of the observed behavior.
Measurement of pore water pressure properties of unsaturated brown coal using triaxial test
- Authors: Couling, Catherine Elizaebth , Tolooiyan, Ali , Mackay, Rae , Xue, Jianfeng
- Date: 2014
- Type: Text , Conference paper
- Relation: 6th International Conference on Unsaturated Soils, UNSAT 2014 p. 1531-1535
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- Description: Skempton's B parameter characterises the effect of fluid compressibility on the time dependent deformation of materials during isotropic loading. The Skempton B-parameter has been determined for a sample of Victorian brown coal for a range of confining pressures, corresponding to the range of conditions which the coal experiences below the ground water table. The relationship between the change in the B-parameter with respect to time and pressure has also been examined. It has been found that a high back pressure (more than 400 kPa) is required in the material to achieve a degree of saturation close to 100+ACU-. The set of data from these tests is able to provide important evidence of the depth and stress dependent behaviour of the coal.
Refined plasticity model for concrete stress-strain relationship part I : Prediction of peak stress and residual stress
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2014
- Type: Text , Conference paper
- Relation: 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23) p. 149-154
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- Description: A refined plasticity model for concrete stress-strain relationships is proposed. The proposed failure surface has the ability to evolve its form based on empirical formulation in which being extracted from the experimental results via the frictional driver parameter (). Two main features are highlighted in this paper such as the peak stress prediction and residual stress prediction of the proposed model. In this paper the comparison of proposed models with experimental results weighted on uniaxial-triaxial compression in axial direction. In the next part of the research a non-associative flow rule in which has an inclusion of size effect to be applied in the constitutive driver is proposed and experimental comparison in both axial and lateral direction is discussed.
- Description: A refined plasticity model for concrete stress-strain relationships is proposed. The proposed failure surface has the ability to evolve its form based on empirical formulation in which being extracted from the experimental results via the frictional driver parameter (
Refined plasticity model for concrete stress-strain relationship part II : Inclusion of size effect
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2014
- Type: Text , Conference paper
- Relation: 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23) p. 155-160
- Full Text: false
- Reviewed:
- Description: This article will discuss about the implementation of size effect into the proposed plasticity model by adjusting the plastic potential function or flow rule. A new parameter (
Distortion index for assessment of damage growth in a composite structures using spectral distortion of embedded FBG sensors
- Authors: Kahandawa, Gayan , Epaarachchi, Jayantha , Canning, John , Lau, Alan
- Date: 2013
- Type: Text , Conference paper
- Relation: 9th International Workshop on Structural Health Monitoring: A Roadmap to Intelligent Structures, IWSHM 2013 p. 175-181
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- Reviewed:
- Description: Structural Health Monitoring Systems based on embedded FBG sensors, to identify damage conditions, are largely dependent on the spectral distortion of the sensors. The uneven stress gradient occurring along the grating of FBG sensors, due to damage inside composite structures can be estimated by analyzing significant changes that appear in the FBG response spectra. However, the stochastic nature of the distorted shape of the FBG spectra makes it difficult to interpret and quantify the existing damage at the location of the FBG sensors. This research works on a novel concept of the "Distortion I ndex (DI)" which is defined using distorted spectra of FBG sensors. I t was observed that the DI increases with t he i ncrease in damage size.
Mixed mode Elasto-plastic model for the fracture analysis of glass using the combined finite-discrete element method
- Authors: Chen, Xiao Dong , Chan, Andrew , Yang, J.
- Date: 2013
- Type: Text , Conference paper
- Relation: CM13: International Conference on Computational Mechanics p. 1-6
- Full Text: false
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A boundary element analysis of non-load-carrying cruciform welded joints strengthened with FRP materials
- Authors: Chen, Tao , Zhao, Xiao , Gu, Xianglin , Xiao, Zhigang
- Date: 2012
- Type: Text , Conference paper
- Relation: International Conferences on Advances in Steel Structures 2012 p. 1405 - 1412
- Full Text: false
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Development of ground thermal conductivity model of multi-layered soils
- Authors: Xue, Jianfeng , Lee, Seung-rae , Yoon, Seok
- Date: 2012
- Type: Text , Conference paper
- Relation: 11th Australia - New Zealand Conference on Geomechanics: Ground Engineering in a Changing World p. 638 - 643
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Formula for SIF of cracked steel plates strengthened with CFRP plate
- Authors: Yu, Qian Qian , Zhao, Xiao , Chen, Tao , Xiao, Zhigang , Gu, Xianglin
- Date: 2012
- Type: Text , Conference paper
- Relation: 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM 2012 p. 537-540
- Full Text: false
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- Description: Fatigue loading will lead to crack initiation and crack growth in steel structures where stress concentration exists. Fatigue life of aged steel members can be extended significantly with carbon fiber reinforced polymer (CFRP) repair. Stress intensity factor (SIF) is a key parameter to calculate the fatigue life and analyze the progress of crack development. There is a lack of knowledge of SIF for cracked steel plate with different degrees of damage strengthened with CFRP. This paper aims to fill this knowledge gap. The SIF formula is developed based on the classical SIF solution and James-Anderson method by considering two correction factors, representing the effect of load share effect in composite system and the effect of initial damage degree, respectively. It is demonstrated that the SIF formula proposed in the paper is applicable to SIF estimation of strengthened center cracked steel plate with different degrees of damage.
Investigation of engineering performance of gravels mixed with additives for unsealed pavement stabilization
- Authors: Huxtable, David , Xue, Jianfeng , Costa, Susanga
- Date: 2012
- Type: Text , Conference paper
- Relation: 11th Australia - New Zealand Conference on Geomechanics: Ground Engineering in a Changing World p. 1244-1249
- Full Text: false
- Reviewed:
- Description: A case study was undertaken to assist Central Goldfields Shire Council, Victoria, Australia, in assessing the success of its unsealed road stabilisation program. A section of road was treated in 2009, with different combination of additives (RT20 and Eko-Soil) and then post construction testing was carried out in 2010 to verify the success of the trial. A set of parameters, including California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), Maximum Dry Density (MDD), and Optimum moisture content was tested after the setting of the additives. The results indicated that Eko-Soil performed better than Reynolds RT-20 in treating the selected site.
Lateral strain of confined concrete incorporating size effect
- Authors: Samani, Ali Khajeh , Attard, Mario
- Date: 2012
- Type: Text , Conference paper
- Relation: 22nd Australasian Conference on the Mechanics of Structures and Materials, ACMSM22; Sydney, Australia; 11th-14th December 2012; published in From Materials to Structures: Advancement through Innovation; p. 357-361
- Full Text: false
- Reviewed:
- Description: The lateral and axial strain relationship plays an important part in predicting the confinement of confined columns. Measuring lateral strains in compressive experiments proves to be difficult which mean few reliable results are available. A lateral strain versus axial strain model is proposed based on the supposition that the concrete behaves linear elastically in the early stages of loading, nonlinear hardening up to the peak stress after which the inelastic lateral strain vary linearly with the inelastic axial strain. The lateral to axial inelastic strain ratio is shown to be a function of the lateral confinement level and related to the failure mechanism. Moreover, size effect is also discussed from the lateral strain versus axial strain perspective.
Reliability analysis of block sliding in large brown coal open cuts
- Authors: Xue, Jianfeng , Tolooiyan, Ali
- Date: 2012
- Type: Text , Conference paper
- Relation: The 2012 World Congress on Advances in Civil, Environmental, and Materials Research (ACEM'12) p. 1578-1587
- Full Text: false
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Statistical downscaling of general circulation model outputs to precipitation
- Authors: Sachindra, Dhanapala , Huang, Fuchun , Barton, Andrew , Perera, Bimalka
- Date: 2012
- Type: Text , Conference paper
- Relation: 34th Hydrology and Water Resources Symposium, HWRS 2012 p. 595-602
- Full Text: false
- Reviewed:
- Description: Victoria suffered a severe drought over the period 1998-2007, when the annual average precipitation plunged by about 13% from the long term average. Precipitation is directly related to the availability of water resources in a catchment. Therefore it is useful to predict precipitation, particularly in light of any future climate change, which will help in the management of water resources at the catchment level. General Circulation Models (GCMs) are considered to be the most advanced tools available for simulating the future climate. Due to the coarse spatial resolution, however, GCM outputs cannot be used directly at the catchment scale. To overcome this problem statistical and dynamic downscaling techniques have been developed. Downscaling techniques link the coarse GCM outputs to catchment scale hydroclimatic variables. The present research has focussed on statistically downscaling monthly NCEP/NCAR reanalysis outputs to monthly precipitation at the catchment level. A precipitation station in the operational area of the Grampians Wimmera Mallee Water Corporation (GWMWater) in northwestern Victoria was considered as the case study. Multi-linear regression was used in the development of the downscaling models. This research employed separate downscaling models for each calendar month, with the intention of better capturing the seasonal variations of precipitation. A set of probable predictors were selected following the past literature and hydrology. Data for the probable predictors and precipitation were split into three 20 year time slices; 1950-1969, 1970-1989 and 1990-2010. The probable predictors which displayed the best statistically significant correlations consistently with precipitation over the three time slices and the whole period of the study were selected as potential predictors, for each calendar month. These potential predictors were introduced to the downscaling model one at a time based on the strength of the correlation, over the whole period of the study, until the model performance, in terms of Nash-Sutcliffe Efficiency (NSE), was maximised. This approach ensured the identification of the best potential predictor for each calendar month. In calibration and validation, the model displayed good performances with NSEs of 0.74 and 0.70 respectively. In calibration, the average precipitation was perfectly reproduced by the model and in validation it was slightly over-predicted. However, both in calibration and validation, the model tended to under-predict high precipitations and over-predict near-zero precipitations. A graphical comparison of observed precipitation, downscaling model reproduced precipitation and the Hadley Centre Coupled Model version 3 GCM (HadCM 3) simulated raw precipitation output, revealed that there is large bias in the HadCM 3 precipitation outputs. Therefore, before producing any future precipitation projections with the downscaling model, a bias correction to GCM outputs is prescribed.
Artificial neural networks for the prediction of the trapping efficiency of a new sewer overflow screening device
- Authors: Phillips, David , Imteaz, Monzur , Aziz, Mubashir , Choudhury, Tanveer
- Date: 2011
- Type: Text , Conference paper
- Relation: 19th International Congress on Modelling and Simulation - Sustaining Our Future: Understanding and Living with Uncertainty, MODSIM2011 p. 3476-3482
- Full Text: false
- Reviewed:
- Description: Some of the major concerns regarding sewer overflows to receiving water bodies include serious environmental, aesthetic and public health problems. Water management authorities are increasingly receiving public complaints that have led engineers to focus on means of retaining the entrained sewer solids within the sewer system during overflow events. During wet weather conditions, sewer overflows to receiving water bodies raise serious concern to environmental and community health concerns. To address these problems, different types of screening devices are used. Moreover, floatable control is preferred by most of the proposed and existing environmental regulations. This requirement triggers the need to research the different types of screening devices and screenings handling systems to select the most appropriate for a particular installation especially at unmanned locations. In the present study the sewer overflow device consists of a rectangular tank and a sharp crested weir that are followed by series of vertical parallel combs to separate entrained sewer solids from the overflow. The device does not require electrical or mechanical power for the self-cleansing mechanism, enabling the device to work efficiently in unmanned locations. Extensive laboratory investigations are underway to assess the effectiveness of a novel self-cleansing sewer overflow screening device. A series of laboratory tests to determine trapping efficiencies for common sewer solids were conducted for different flow conditions, number of combs layers, spacing of combs and weir crest lengths. Sewer solids from different density materials make sewer flow to analyze in complex Non-Newtonian fluid system with huge computational cost and complicity using physical law based modeling. On the flipside artificial neural model has the capacity to accurately predict the outcome of complex, non-linear physical systems with relatively poorly understood physicochemical processes which makes them highly desirable in the present study. Artificial Neural Networks (ANN) have already been successfully used to simulate flood forecasting in urban drainage system, real time control in combined sewer system, real time water level predictions of sewerage systems covering gauged and un-gauged sites etc. In case of sewer solid capture efficiency: neural network modeling is able to recognize nonlinear input output relations with adapting approach for changing circumstances. In the present study, feed forward artificial neural networks using back propagation algorithms were used, as such networks have been used almost exclusively in environmental modeling. A series of forty seven (47) sets of experimental data were collected to train (calibrate) the ANN model. In addition to these, eight (8) sets of experimental data were collected to validate the trained ANN network to be used in wider prospective of urban drainage conditions. The major areas covered in the ANN modeling include selection of input and output variables, optimization of the model, consideration of different learning algorithms, designing ANN's training & cross training processes and model validation. In the studied case, complex physical characteristics of different sewer solids, together with multi-fluid sewer system with variable flow phenomena makes it difficult to model with physical considerations. In case of sewer solid capture efficiency; artificial neural network modeling is able to learn the complex input-output relations with adapting approach for changing circumstances. Model considered different learning algorithms, diverse hidden layer structure with varied training samples to optimize the network. It is found that the model can successfully predict the experimental results with average absolute percentage errors varying from 4 to 7 percent.
Modified stress intensity factor equations for semi-elliptical surface cracks in finite thickness and width plates
- Authors: Peng, Yang , Tong, Lewei , Zhao, Xiao , Xiao, Zhigang
- Date: 2011
- Type: Text , Conference paper
- Relation: The Twelfth East Asia-Pacific Conference on Structural Engineering and Construction p. 2601-2608
- Full Text: false
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- Description: Weld defects and severe variation of shape near the welds cause high stress concentration at weld toes or weld roots. This high stress concentration reduces fatigue lives of welded structures. A stress intensity factor (SIF) which includes this effect increases the accuracy of fatigue lives prediction. A magnification factor is commonly used to multiply the SIF of semi-elliptical surface cracks to account for the stress concentration effect in welded connections. Yamada and Hirt model is one of these methods. Comparison between Yamada & Hirt SIF equations and Newman & Raju SIF equations are applied to SIF of semi-elliptical surface cracks. The results suggest that Yamada & Hirt SIF equations are valid when the crack aspect ratio is less than 0.6. New empirical SIF equations are developed based on Yamada & Hirt SIF equations. The newly derived SIF equations are verified by comparing with experimental data.
A new model for confined concrete
- Authors: Samani, Ali Khajeh , Attard, Mario
- Date: 2010
- Type: Text , Conference paper
- Relation: 21st Australasian Conference on the Mechanics of Structures and Materials p. 227-232
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- Reviewed:
- Description: Analytical models for the stress-strain relationship of confined and unconfined concrete in compression are required for modeling the structural behavior of the reinforced concrete structural elements. The presented paper reviews the widely used models by Attard & Setunge (1996) and Binici (2005) and compares them with test results on uniaxial and triaxial tests with different specimen heights and widths and concrete strength. The variation of peak stress and corresponding strain, as well as the residual stress level, under confinement are compared with experimental results and discussed. A new analytical model is introduced which tries to address the limitations in previous models. The proposed model is capable of predicting the behavior of normal strength as well as high strength concretes.
Fatigue testing of subsea pipeline steel connections under combined actions
- Authors: Liu, Huihua , Zhao, Xiao , Xiao, Zhigang
- Date: 2010
- Type: Text , Conference paper
- Relation: Incorporating Sustainable Practice in Mechanics of Structures and Materials - Proceedings of the 21st Australian Conf. on the Mechanics of Structures and Materials p. 649-654
- Full Text: false
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- Description: This paper describes a set of experimental tests of subsea pipeline steel connections under combined forces: one set of force is fatigue load, which is the simulation of the variation caused by currents or waves flowing across pipelines; another set of force is hoop force, which is constant tension force introduced by internal and external pressures. The steel connections are made of two steel plates joined together by single-sided girth welds. One central notch is machined on the weld toe. The specimens under combined forces are compared with those subjected to fatigue loads alone. It is found that the hoop force could affect the fatigue life of subset pipeline steel connections and also reduce the initiation angle of the crack propagation.
Shrinkage development during soil desiccation
- Authors: Costa, Susanga , Kodikara, Jayantha
- Date: 2010
- Type: Text , Conference paper
- Relation: Unsaturated Soils: Theoretical and Numerical Advances in Unsaturated Soil Mechanics - Proceedings of the 4th Asia Pacific Conference on Unsaturated Soils p. 433-436
- Full Text: false
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- Description: Clayey soils undergo shrinkage during desiccation. When shrinkage is restrained by the boundary conditions or by internal stresses, tensile stresses are generated within the soil body. These stresses eventually produce tension crackswhich create problematic situations in many engineering applications. Presence of shrinkage cracks is significant in many applications such as earth embankments, landfill clay liners, foundations, and road pavements. Desiccation or thermally induced induced shrinkage cracks cause problems in other disciplines as well, for example in mining engineering, agricultural engineering and materials engineering. It is important to understand the shrinking behavior of soil in order to study the desiccation crack development in clayey soils. Free shrinkage of slurry clay was observed in laboratory experiments. Image analysis, along with Particle Image Velocimetry (PIV) technique was used to analyze the data obtained. Relatively small specimens 100 mm longwere used so that strains could be measured to high accuracy.Werribee clay, an expansive clay found in West Melbourne, was used in the experiments. Basic clay properties include liquid limit of 127%, plasticity index of 101 and linear shrinkage of 22%. This paper discusses the relationship between strains (vertical, horizontal, and volumetric), displacements, water content, degree of saturation and void ratio. Shrinkage strain development prior to crack initiation was examined to identify crack failure condition.
Size effect in confined concrete
- Authors: Attard, Mario , Samani, Ali Khajeh
- Date: 2010
- Type: Text , Conference paper
- Relation: 21st Australasian Conference on the Mechanics of Structures and Materials p. 221-226
- Full Text: false
- Reviewed:
- Description: Compressive size effect tests have been mainly conducted on uniaxial compression tests. However, softening in concrete happens not only in uniaxial compression but also under triaxial compression. The present study shows that the post-peak compressive fracture energy per unit area, is influenced by the level of confinement in triaxial loading. The results estimated from the literature show an increasing fracture energy with increasing confinement until a limit is reached, at a confinement ratio of about 10 to 20% after which it decreases until it becomes zero. The fracture energy, the specimen height, aspect ratio and the confinement level is shown to influence the softening behavior of both uniaxially and triaxially loaded concrete. A new stress strain model is proposed for unconfined and confined concrete. The proposed model takes account of size effects dependent on specimen height and aspect ratio. The model is compared to experimental data and shows excellent agreement.