Roads and Traffic Authority
Roads and Traffic Authority
Indraratna B.,University of Wollongong |
Rujikiatkamjorn C.,University of Wollongong |
Kelly R.,Coffey Geotechnics |
Buys H.,Roads and Traffic Authority
Proceedings of the Institution of Civil Engineers: Ground Improvement | Year: 2010
The application of prefabricated vertical drains combined with vacuum and surcharge preloading is considered to be one of the most environmentally friendly ground improvement techniques. The natural atmospheric pressure is used to generate suction via a vacuum pump. In comparison with other ground improvement methods such as deep piling and deep mixing, this method will not only save a substantial cost in road and rail embankment maintenance and construction but will also enhance the speed of construction of coastal highways and rail tracks and their capacity to carry a greater traffic load. Moreover, as drains with vacuum pressure do not involve chemicals, the soil and groundwater chemistry will not change, unlike cement and lime treatment. Vacuum preloading will also reduce the impact on the environment by minimising the greenhouse gas emissions and the need for quarrying natural sand and gravel. The performances of three full-scale test embankments constructed in Thailand, China and Australia are discussed collectively, demonstrating the advantages and environmental benefits of vacuum consolidation in relation to a standard surcharge-only system.
Hendrickx M.,Coffey Geosciences Pty Ltd. |
Wilson R.A.,Coffey Geosciences Pty Ltd. |
Moon A.T.,Coffey Geosciences Pty Ltd. |
Stewart I.E.,Roads and Traffic Authority |
Flentje P.,University of Wollongong
Australian Geomechanics Journal | Year: 2011
Lawrence Hargrave Drive was constructed in 1878 and has experienced a continuance of slope failures including rock falls, debris flows and embankment collapses. In 2003 a section of the road was closed for safety reasons. An Alliance between the state government and private industry was formed to develop an engineering solution to reduce the risk to 'acceptable' levels. Assessment of slope hazards was completed with the aid of geological mapping, interpretation of aerial photographs, archived government reports, historical photo and newspaper collections and a GIS based landslide inventory. Historical photographs provided important evidence on erosion rates and the size, nature and frequency of landslide events. A landslide process rate model was developed for the site bringing together knowledge and judgments about erosion rates for the differing materials and landforms on the escarpment. Process rate curves were developed for slope units and integrated into a quantitative risk assessment.
Samali B.,University of Technology, Sydney |
Crews K.I.,University of Technology, Sydney |
Aboura K.,University of Technology, Sydney |
Ariyaratne W.,Roads and Traffic Authority |
Manamperi P.B.,Roads and Traffic Authority
Incorporating Sustainable Practice in Mechanics of Structures and Materials - Proceedings of the 21st Australian Conference on the Mechanics of Structures and Materials | Year: 2011
Traditionally, bridge management systems were designed using a Markov chain decision model. Based on the analysis of 15 years of bridge inspection data, we apply the gamma process instead. After extracting all relevant information, enough data was collected on the condition paths of elements to build a deterioration model.The element conditions followa time period in full condition then start deteriorating.We consider a random variable for the last time the condition was observed to be 100%.We consider the stochastic deterioration process that follows. The amalgamation of the two part process through probabilistic arguments creates a new stochastic process. The novel stochastic process characteristics are derived through the data to provide a predictive model for the element, bridge and network conditions.We showcase a software solution for bridge network condition assessment, monitoring and prediction. © 2011 Taylor & Francis Group, London.
Karim M.R.,University of New South Wales |
Gnanendran C.T.,University of New South Wales |
Lo S.-C.R.,University of New South Wales |
Mak J.,Roads and Traffic Authority
Canadian Geotechnical Journal | Year: 2010
This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elastic-viscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite element analysis (FEA). A unit-cell analysis is carried out to capture the maximum settlement and the development of excess pore-water pressure with time below the centreline of the embankment for a long period (9 years). A new function for capturing the varying nature of the creep or secondary compression coefficient is proposed and used in association with the EVP model. The input material parameters for this study were determined from extensive laboratory experiments except for the equivalent horizontal permeability, which was systematically estimated by using vertical permeability data obtained from one-dimensional consolidation tests and by back-analysing the first 12 months of field settlement data. Comparisons are made among the predictions obtained adopting an elastoplastic modified Cam clay model and the EVP model with constant and varying creep coefficients for the foundation soil and the corresponding field data. The predictions with the EVP model are found to be better than those with the elastoplastic model and the use of a varying creep coefficient for the EVP model seems to further improve its predicting ability.
Lo S.R.,University of New South Wales |
Zhang R.,University of New South Wales |
Mak J.,Roads and Traffic Authority
Geotextiles and Geomembranes | Year: 2010
This paper presents the findings of a series of numerical studies on the contribution of geosynthetic encasement in enhancing the performance of stone columns in very soft clay deposits. In this study, the imposed loading is from a fill embankment, and the stone columns act like reinforcements. Observed settlement of a trial embankment built on very soft clay strengthened with stone columns indicated that the stone columns alone were not adequately effective in reducing settlement because the very softy clay could not provide adequate confining stress to the stones. An alternative system utilizing geosynthetic encasement was examined numerically. As the primary issue is the development of settlement with time after the completion of stone column installation, a fully coupled analysis was performed. To reduce the computational effort, a unit cell idealization was adopted. This study showed that the use of geosynthetic encasement has the potential of significantly enhancing the effectiveness of stone columns in very soft clay and the simplified analysis presented in earlier work is valid. Furthermore, the predicted performance was found to be insensitive to assumed stiffness parameters of the compacted stone. However, it was found to be dependent on the locked-in stress in the geosynthetic encasement induced during installation. © 2009 Elsevier Ltd.
Dumitru I.,Boral Construction Materials |
Song T.,Boral Construction Materials |
Caprar V.,Boral Construction Materials |
Brooks P.,Roads and Traffic Authority |
Moss J.,Roads and Traffic Authority
2nd International Conference on Sustainable Construction Materials and Technologies | Year: 2010
Laboratory investigations were carried out to assess the potential of the crushed recycled glass as natural sand replacement using ratios of 30%, 45% and 60%. Replacement of cementitious materials in concrete was also considered using cement replacement ratios of 7.5%, 15% and 25% of powder glass. The effects of glass sand replacement and cementitious materials replacement with powder glass on fresh and hardened concrete properties were assessed. It was concluded that with the incorporation of 45% of crushed glass as a natural sand replacement, the compressive and flexural strengths have marginally increased, while the indirect tensile strength marginally decreased. The concrete with glass as the natural sand replacement had lower shrinkage and significant lower chloride diffusion coefficient. Concretes with powder glass as cementitious materials replacement showed lower compressive strength and marginally higher drying shrinkage than the control mix, but meeting the concrete mix design requirements.
Fernandes R.,University of Sydney |
Hatfield J.,University of Sydney |
Soames Job R.F.,Roads and Traffic Authority
Transportation Research Part F: Traffic Psychology and Behaviour | Year: 2010
Risky driving has been identified as a key contributor to road crashes. Past research suggests that different risky driving behaviours are influenced by different factors, but has not been systematic in its investigation of the factors associated with different behaviours. The present research systematically examined a range of relevant demographic, personality and attitudinal factors (age, gender, sensation seeking, driver anger, time urgency, authority rebellion, perceived relative risk, perceived personal risk, perceived costs, perceived benefits, and peer influence) in the prediction of speeding, drink-driving, driving while fatigued, and not wearing seat belts, for a student sample of young drivers. In addition, relevant mediators of the relationship between gender and risky driving, as well as moderators of the relationship between perceived risk and risky driving, were examined for each of the four behaviours. Results demonstrate that the lists of significant predictors differed between risky driving behaviours. In addition, perceived personal risk was observed to mediate the relationship between gender and driving while fatigued only, and gender was observed to moderate the relationship between perceived risk and risky driving, for drink-driving and not wearing seat belts. Results highlight the importance of designing individual road safety interventions for individual driving behaviours, and suggest factors which might be targeted in younger driver populations. © 2010 Elsevier Ltd.
Tripathi N.,Roads and Traffic Authority
18th International Corrosion Congress 2011 | Year: 2011
This paper presents failure investigation and analysis of corrosion of elements of a tunnel wall panel system containing galvanized steel frames supporting the architectural wall panels on the sides of a tunnel. These wall panels were installed in around year 2001. The panels were mounted on galvanized steel frames using stainless steel screws through Aluminium strips. The specification for the wall panel system was based on performance and required the system to have 25 years design life. However, the elements of the wall panel system started showing sign of corrosion within ten years of installation. An investigation into the root cause of the problem was carried out. This involved inspection and visual examination of the elements of the wall panel and sampling of water that was present due to seepage from the tunnel walls. The failure analysis identified presence of Chloride in water around the support frames and the contact of dissimilar metals resulting in galvanic corrosion of the elements. The corrosion was apparent in the elements of the wall panel system only at the locations where there was ponding of water. The paper examines the provisions in the performance specification, describes the corrosion mechanism and reviews the proposed remedial measures.