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General And Technical Considerations For Implementing High Speed Rail Systems In Australia
Australia has a number of medium speed rail services such as the Prospector, which runs from East Perth to Kalgoorlie, at speeds of up to 160 km/hr. Speeds as high as 210 km/hr have been reached by the tilt train from Brisbane to Rockhampton. Although there are a few medium speed rail systems in Australia, there is not a passenger rail transport with the high transit speeds seen in other countries. This paper presents the feasibility of implementing high speed rail systems in Australia by looking at the main elements that a high speed train is composed of. This paper also reviews the performance of high speed rail systems around the world and the factors contributed to their success made them successful. The main objective of this study is to look at how the solutions from overseas and how the technical requirements particularly the geotechnical aspects of tracks for a high speed rail system can be applied in Australian existing and new tracks. Australia has its own unique demographic, geographic and economic characteristics and the aim is to identify where there are overlaps between Australia’s characteristics and countries with high speed rail systems. High speed rail transport might not necessarily be one the best solutions for the transportation at present in Australia, but it can be what a nation needs to succeed in its future transportation system.
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Technical Note: Determination Of Young’s Modulus And Poisson’s Ratio For Intact Stratified Rocks And Their Relationship With Uniaxial Compressive Strength
Determining linear elastic stiffness parameters is a crucial aspect of ground characterization that enables subsequent numerical analyses using finite element, discrete element, and other procedures. Before estimating global settings for a rock mass relative to a proposed excavation such as a rock slope, tunnel or cavern, it is essential to understand parameters of the intact rock first. The main objective of this paper is to investigate the new linear correlations between different elastic parameters and strength of the intact rock. Three essential parameters that need to be determined for intact rock are unconfined compressive strength (UCS), secant and tangent Young’s Modulus (Es and Et), and secant and tangent Poisson’s Ratio (s and t). It is of particular interest to recognize that obtained results show a high correlation between linear elastic parameters.
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Some notes on the design of pile foundations in sedimentary rock
This paper presents some technical notes on the design of pile foundations in sedimentary rock based on the author’s thirty-year research and consulting experiences. Firstly, the fundamental difference between the superseded working stress method and the current ultimate limit state (ULS) approach within the practicing codes will be discussed from a geotechnical engineer’s perspective. Then some delusion and confusion encountered by practicing geotechnical engineers such as rock classification and the characteristics of each rock class will be highlighted. The importance of soil and structure interaction and establishment of design criteria for structures and substructures will be emphasized. An overview of the published methods for assessing the pile end bearing capacity and lateral resistance will be carried out to appreciate some issues that practicing engineers are often required to deal with. For typical bridge pile foundations and piled deep excavation retention or retaining structures, both serviceability limit state and ultimate limit state assessments are required to satisfy the requirements set out in current codes of practice. For vertically loaded piles in sedimentary rock it is found that the serviceability limit state is governing the design rather than the ultimate limit state condition for most road and railway projects, based on the commonly accepted design parameters. For laterally loaded piles in rock it is noted that the method based on the lateral force and bending moment equilibrium such as described in Hong Kong Geoguide 1 is frequently used to determine the pile socket length. The critical input parameter required by this method is the ultimate lateral resistance of the rock mass, which is often arbitrary with little guidance provided, and a degree of confusion is often noted by the author. It is proposed to undertake a lateral equilibrium assessment under ULS conditions for a piled wall along with analysis of the deformation characteristic of the rock mass to come up with the “mobilised” rather than the ULS lateral pressure for pile socket design. Worked examples will be given to demonstrate how the pile socket in sedimentary rock can be determined with reasonable confidence for a cantilever piled wall for tunnel projects, and for a bridge structure.
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The Australian geoguides for slope management and maintenance
The Australian Geomechanics Society (AGS) presents on the following pages a guideline on slope management and maintenance, as part of the landslide risk management guidelines developed under the National Disaster Funding Program (NDMP). This Guideline is aimed at home owners, developers and local councils, but also has applicability to a larger audience which includes builders and contractors, consultants, insurers, lawyers, government departments and in fact any person, or organisation, with a responsibility for the management or maintenance of a slope. The objective is to inform those with little or no knowledge of geotechnical engineering about landslides.
Each GeoGuide is a stand-alone document, which is formatted so that it can be printed on two sides of a single A4 sheet. It is expected that the set of GeoGuides will increase with time to cover a range of topics. As things stand:
- GeoGuide LR1 is an introductory sheet that should be read by all users, since it explains what the LR (landslide risk) series is about and defines terms.
- GeoGuides LR2, 3 and 4 explain why landslides occur and provide information on different types of landslide.
- GeoGuide LR5 discusses the critical part that water often plays in relation to landslide occurrence and discusses measures that can be adopted to limit its effect.
- GeoGuide LR6 refers to retaining walls and their maintenance.
- GeoGuide LR7 puts the concept of landslide risk into an everyday context, so users can relate a particular landslide risk to other risks that they know they are prepared to take, sometimes on a daily basis.
- GeoGuide LR8 retains the ideas of good and poor hillside construction practice originally provided by an AGS sub-committee in 1985.
- GeoGuide LR9 concentrates specifically on effluent and surface water disposal, which is an important topic in some development areas.
- GeoGuide LR10 is specifically aimed at those who have property on the coast and could be susceptible to coastal erosion processes.
- GeoGuide LR11 provides information about the benefits of keeping records on inspection and maintenance activities and provides a proforma record sheet for users.
It is recognised that the GeoGuides are likely to be upgraded from time to time. Feedback on use and suggested changes should be sent to the National Chair of the Australian Geomechanics Society. The latest versions of the GeoGuides will be downloadable from the AGS website www.australiangemechanics.org
Through the NDMP, Australian governments (at Commonwealth, State and Local Government levels) are also funding the development of a Landslide Zoning Guideline (AGS 2007a), and a Practice Note Guideline (AGS 2007c) to which interested readers seeking in-depth information should refer.
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Characterisation of municipal solid waste materials for the purpose of engineering design in transport infrastructure project
Space restriction especially in the urban area has contributed to the reuse of landfill area, where Municipal Solid Waste (MSW) is disposed, for the purpose of infrastructure development. This type of development presents some significant challenges in the engineering design due to high variability of MSW properties and the uncertainty in relation to the application of conventional geotechnical engineering principle for the engineering design involving MSW materials. MSW materials are highly variable not only in different landfill sites, but they also are likely to vary over the distance and depths within a landfill site. In addition, the engineering properties of MSW materials are influenced by a number of factors including the landfill age, constituents of landfill, placement method and the leachate recirculation. This variability along with a risk associated with the biological and chemical hazards arising from the direct exposure to the waste materials and toxic gas pose limitations in conventional (a) geotechnical site investigation and (b) laboratory testing of MSW. Therefore, characterisation of MSW for the engineering design needs to be carried out based on limited site specific information and published data. This paper presents a typical geotechnical investigation and characterisation of waste materials for the engineering design of a transport infrastructure considering the aforementioned limitations. A case study involving a proposed transport infrastructure over an active landfill site in NSW has been selected. A Geotechnical Site Investigation (SI) involving a sonic borehole drilling has been carried out with a primary objective of obtaining continuous samples for the observation of waste materials as opposed to the in-situ testing and drilling with poor recovery. In addition, test pit excavation and geophysical investigation have been carried out to gather more information to develop the geotechnical model. Various MSW materials recovered in the boreholes and test pits were thoroughly assessed on site during the SI to obtain the MSW composition including the proportion of each type of waste material using the method outlined in Landva and Clark (1990). This observation was then compared against the results of geophysical investigation. By using the outcome of SI, previous geotechnical investigation and settlement monitoring conducted about 30 years ago within the subject area and extensive published data on MSW properties including the Waste Compressibility Index, a comprehensive guide has been prepared to develop the design parameters for geotechnical design of the proposed rail embankment. This guide will be a useful tool for practicing engineers to develop geotechnical design parameters of landfill materials.
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Assessment of Methodologies for Reburial of Excavated Acid Sulfate Soft Soils Within Shell Cove Boat Harbour Zone
A study was carried out to assess the practical aspects of placement of excavated disturbed Acid Sulfate Soft Soils (ASSS) within the future Shell Cove Boat Harbour excavation zone at the proposed Shell Cove Boat Harbour development. The objective of the work was to assess and comment on the methodology from a geotechnical perspective for the placement of ASSS material ‘in the moist’ rather than as ‘dredged slurry’, during Stage 2 of construction. Two large field trial cells (approximately 15m by 15m at base, and 4.5m high) were constructed to practically observe, test and assess different placement scenarios. The following three scenarios were assessed:
- Placement of untreated ASSS material
- Placement of Agricultural lime treated ASSS material to modify soil shear strength and consistency
- Placement of Hydrated lime treated ASSS material to modify soil shear strength and consistency
Track rolling via long reach excavators and swampy dozers were utilised to place, spread and remove the large air voids between clumps/clods of the ASSS material within the trial cells. The neutralisation capacity of the various limes for treatment of Acid Sulfate Soil was also assessed in a preliminary manner. It should be noted that the focus of the work from the addition of lime was on geotechnical modification/stabilisation aspects rather than assessment of Acid Sulfate Soil neutralisation capacity.
Shear strength of ASSS material was assessed using a hand-held shear vane. The shear strength of the soils was measured at the borrow pits prior to excavation of material. It was then compared with the measured shear strength of the soil in different layers placed within the trial cells for different scenarios. Comments are provided in relation to the effects of the mixing agent on the shear strength of the soil.
Construction of bunds within harbour excavation zone including bund sizing and stability of bund to be used by earthmoving plant was also assessed and commented on. Change in soft soil pH due to addition of agricultural and Hydrated limes was also assessed. Waiting time to place subsequent layers within the cells and the effect of weather conditions on the placed soft soils within trial cells is also discussed to some extent in this paper.
Utilisation of a new type of long reach excavator not previously used in Australia is also discussed. This innovative construction technique enabled the excavator to travel directly onto soft disturbed soils and to spread the soils within the harbour excavation zone in a manner that provided enormous cost and time savings for the client.
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Design solution to a heritage piled rail bridge foundation using numerical modelling technique
This paper presents a case study of replacement works for a more than 100-year old rail bridge over Guess Avenue, Wolli Creek, Sydney. Firstly, the as-built drawings for the existing railway bridge and brick abutments were reviewed and a summary of findings is presented. A geotechnical investigation program was devised to assess the existing timber pile and pile cap conditions below the brick abutments, which is heritage listed, and the subsurface geological profile for the bridge site. The preferred option using filler beam units enabled the clearance of the new bridge above the existing road to be increased from original 4.13 m to 4.6 m, which is in compliant with the current Australian bridge standard AS5100. The ultimate capacity of a single pile was assessed as the lesser of its structural capacity and geotechnical capacity using the obtained investigation results; the geotechnical capacity of the pile governs. A factor of safety of 2.5 was considered appropriate to evaluate the adequacy of the pile capacity under the existing bridge and future bridge loading conditions. The pile loading was initially assessed using program Piglet based on the as-built drawings and the findings of the geotechnical investigation. Due to much higher loads calculated for the edge piles using the Piglet program which exceeds the assessed capacity of a single pile, Plaxis 3D modelling was carried out for both existing and the future bridge loading conditions. The results of Plaxis 3D modelling indicate that the piles are unlikely to be over-loaded beyond the assessed capacity of a single pile. Based on this comprehensive assessment of the pile load and the use of the piled raft concept we recommended to Sydney Trains that the existing pile foundations and brick abutments be used for the future bridge without any underpinning or foundation strengthening. At the time of writing this paper the bridge replacement has been completed, with the monitored movement of abutments being within the prediction.
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Geotechnical Aspects Of The Mid-West Rail Upgrade Project In Western Australia
This paper presents a description of the geotechnical aspects associated with the design and construction of the MidWest Rail Upgrade project in the Mid-West region of Western Australia. It covers aspects of site investigation on existing track formation and track duplication alignments, assessment of the capacity of existing bridge foundations, methods for assessment of the suitability of existing rail formation and upgrades required, analysis of railway behaviour in salt lake areas and recommended ground improvement schemes as well as design of formation-to-bridge transition zones. The paper presents results from a constructability study carried out to assess the stability of operational existing track during construction of duplicated portions of the line. It also describes methodology and results of borrow source investigations for both main sections of the project and geotechnical related issues that arose during the construction stage.
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Sydney Symposium 2021
Geotechnical Lessons Learnt – Building and Transport Infrastructure Projects
Andrew Leventhal, Prof. Buddhima Indraratna, Kim Chan, Patrick Wong, Dr David Och and AHM Kamruzzaman
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Development and application of models for the stability analysis of Australia’s offshore pipelines
Offshore subsea pipelines are used to export oil and gas from the field to platform and then from the platform to the mainland. As they are the sole conduit for the hydrocarbons their stability and integrity are of critical economic and environmental importance. With more than 80 per cent of Australia’s gas resources in deep, remote, offshore areas, the ability to realise their full potential relies on the development of safe and economically viable solutions to transport them. Pipelines offshore of Australia must maintain structural integrity and continuous supply of products across hundreds of kilometres of seabed. This paper discusses one aspect of this challenge. It concentrates on how to design for stability of untrenched pipelines under storm conditions. Force balance methods commonly applied are first described before the benefits of using a dynamic time domain approach are shown by way of example. Novel macroelement plasticity models that describe the force-displacement behaviour of a vertically and laterally loaded pipe in Australian soils are outlined. Their application is shown in the design example.