Australian Geomechanics Society Sydney – 2008 Meetings
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February 13, 2008
Vacuum Consolidation of Soft Clay via Vertical Drains
Buddhima Indraratna
In many countries, the majority of population lives along the coast, which contains soft soil deposits that require ground improvement. Loose sandy soils and soft compressible clays are very common along the coastal regions. The use of vertical drains with vacuum preloading is considered as the most effective and economical method for improving soft clays (normally consolidated to lightly overconsolidated) to eliminate settlements of the permanent infrastructure. Application of vacuum pressure via prefabricated vertical drains promotes radial flow consolidation enhancing the shear strength of the compressed ground. In this presentation, the mechanisms of the vacuum preloading system based on current practices are described through the selection of important design parameters. An advanced analytical solution based on actual radial soil permeability is proposed considering the variation of vacuum pressure. The Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains. The predicted smear zone and the effect of drain unsaturation are compared with data obtained from a large-scale radial consolidation tests and the results are explained.
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March 12, 2008
Design and Construction of Asphalt Concrete Core Embankment Dams
Behzad Fatahi
The presentation focuses on design and construction methods of ACC and transition zones of earth fill dams. Specific attention will be given to the construction of Meijaran dam in the Middle East. Meijaran dam is approximately 54m high with a 1m wide core, and is the first of its kind in Iran. Brief technical specifications of ACC including construction techniques, laboratory tests and field measurements will be reviewed. Finite element analysis of Meijaran dam with special attention on core parameters will also be discussed.
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April 9, 2008
Lane Cove Tunnel Retaining Structures
Paul Hewitt
The Lane Cove Tunnel connects the M2 Motorway at North Ryde with the Gore Hill Freeway and the Pacific Highway at Artarmon. Design and construction involved about 70 retaining structures which included braced and anchored bored pile walls, soil nailing, reinforced soil wall systems and post-tensioned cantilever walls. Significant challenges related to restricted site access, the need to minimise construction impacts, a tight design schedule, and stringent settlement and angular distortion criteria.
Rigorous assessment of the effects of new construction on existing structures and construction safety utilised advanced numerical techniques to model ground-structure interaction. This talk discusses various geotechnical issues affecting design and construction, how the design was implemented in the field, and documents results of performance monitoring.
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April 16, 2008
Technical Meeting – “Blasting in the Urban Environment”
Martin Adam
Drilling and blasting for civil construction is a process that is sometimes unnecessarily excluded from consideration in tenders and project specifications. However modern blasting technology has made breaking rock with explosives safer, more secure, and more productive than ever before.
This talk will cover some of the practicalities of blasting in built up areas, with discussion of the key safety measures that can be used to control vibration, airblast and flyrock. Case studies of some major urban drill and blast projects will be presented.
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May 14, 2008
Engineering Geologists and Risk Management
Dr Sergio Mora-Castro
Dr Mora is currently on a speaking tour of Australia and New Zealand and is eminently qualified to speak on the top of risk management having until recently held the position of Environmental, Natural Resources and Risk Management Specialist at the Inter-American Development Bank and before that Professor of Geotechnical Geology, Soils and Rocks Mechanics and Natural Hazards Assessment at the Central American School of Geology, University of Costa Rica.
Dr Mora will discuss the risks that Engineering Geologists face in two different contexts:
- Deciphering risk as a derivation of natural hazards and vulnerability; and
- Risk, as we face it on our daily professional work, by tackling the normal uncertainties of our trade.
Dr Mora will challenge our professional paradigms: don't we trust a bit too much the standards and codes? Don't we take them as prescriptions shadowing our own judgment and creativity? Do we take too little advantage of our natural vocation of being able to read nature? If we are able to develop the good arguments, how do we overcome the enormous difficulties influencing and assisting decisionmakers?
Dr Mora will discuss the risk management process using case studies from a diverse range of natural hazards including volcanic, seismic, climatic and slope hazards and will challenge us about the notions of risk acceptance and vulnerability.
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June 11, 2008
Geotchnical Aspects of the Eastern Busway and South East Queensland Infrastructure Plan Rail Program Alliance Projects
Patrick Kidd
In May 2007, the Queensland Government updated its $82 billion blueprint for upgrading a range of infrastructure in South East Queensland (SEQ). The South East Queensland Infrastructure Plan 2006-2026 (SEQIP) outlines two decades of development of road, rail, water, energy, health, education and community infrastructure. Of this, $35 billion has been allocated for a roads and transport package for roads, rail, buses, walking and cycling, with a potential additional $15 billion dollars also being considered for transport infrastructure.
The presentation will give a brief overview of each of these projects and discuss the aspects of the geotechnical engineering for each of the projects, with a focus on the Eastern Busway and the Robina to Varsity Lakes projects.
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June 16, 2008
A Brief Introduction to the Monitoring of Urban Tunneling Projects
Dr David Bassett
In this short talk, Dr Bassett will set out a complete philosophy of planning, installing and assessing instrumented tunnelling projects in soft soils and hard rock ground. Approaches to observing and recording factors such as tunnel displacement, vertical settlement and horizontal strains will be discussed, along with the purpose, importance and correct procedure of implementing effective monitoring systems. The various parameters affecting any tunneling project will be explored, and effective methods to measure, analyse and react to these covered.
The aim is to give the attendee the tools needed to assess their own project and clearly appreciate the confidence and value a well structured monitoring program can provide.The presentation will be followed by a question time, in which Dr Bassett would be glad to answer any questions from the floor.
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July 9, 2008
Role of the Principal Contractor
Coreena Smith
An introduction to the role of the Principal Contractor, the level of skill and expertise necessary to fulfill the role and the risks and liabilities which companies and individuals assume when taking on this role. Summary discussion on the key legislative requirements and the different triggers that activate the principal contractor role, and in particular, the different work environments and contracting activities that may trigger such responsibilities. Specific focus is given to the approach that can be adopted by Consultants in managing their subcontractors’ compliance with OH&S requirements and dealing with the risk of assuming the Principal Contractor role.
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August 13, 2008
Reducing Slope Risk on Lawrence Hargrave Drive
Alan Moon
Lawrence Hargrave Drive north of Wollongong is one of the most scenic coastal roads in New South Wales. Several years ago a section of the road was judged to have the highest slope risk in the state with a long history of rock falls, debris flows, embankment failures and road closures. In 2003, the State Government closed the road and the Roads and Traffic Authority (RTA) signed an alliance agreement with Barclay Mowlem, Coffey and Maunsell to investigate options and design and carry out a major project to upgrade the road. The project, including the spectacular Sea Cliff Bridge, was completed in late 2005 and has become a major tourist attraction.
The presentation by Alan Moon will deal with geotechnical aspects of the project including the hazard investigation, risk assessment and adopted solutions which included bridges, extensive slope stabilisation and protection works. There is particular emphasis on understanding the slope hazards and the risk assessment.
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September 10, 2008
Young Geotechicnal Professionals’ Night
Investigation of the Piles Creek Embankment Collapse
Peter Retsos
An embankment at Piles Creek failed during heavy rain in June 2007. Five deaths occurred when a vehicle then drove into the void created by the collapse. The subsequent investigation of the collapse was undertaken by Connell Wagner in a collegial manner with expert representatives from the RTA and Gosford City Council. In this presentation, Peter will discuss the methods used during the field investigations and the advantages and disadvantages of undertaking a collegial investigation. He will also reflect on the benefits and skills gained from examining a failure of this nature.
Jointing and Dyke Structures in Top Ryde, Sydney
Kathryn Pike
The ongoing construction of the Top Ryde Shopping Centre involves excavation to depths varying between 10m and 25m below ground surface. Preliminary investigations identified an igneous dyke in the northern corner of the site and high angle joints. These features have been progressively revealed during the excavation process. Kathryn will present the results of mapping, analysis and interpretation of the geological and structural features encountered. The study of such features will allow engineers to make improved predictions of areas of rock affected by dyke structures and their associated jointing.
Ground Improvement for Rail Embankment Construction on Soft Ground
Ted Tse
A 4.3km railway line is proposed as part of the development of the Coal Export Terminal 3 on Kooragang Island, Newcastle. The proposal involves the construction of embankments up to 10m high, to be formed over soft ground, water ponds, coal washery rejects and slag bunded emplacement cells. Investigation and testing for the site included two stages of field investigation, laboratory tests and a full scale trial embankment. Ted will present the challenges encountered in the design of the rail embankment, including the investigation and selection of various ground improvement options.
Modelling of Infilled Rock Discontinuities
David Oliveira
One of the most challenging tasks when designing structures on or within a rock mass is the modelling of the mechanical behaviour of the rock. This is typically due to the rock mass comprising interlocking discrete blocks and the varying conditions of the rock joint surfaces. Among these contact surfaces, infilled rock joints are likely to be the weakest planes. David will present a review of studies involving the shear behaviour of infilled rock joints and some of the most recent advances in modelling. A new semiempirical yielding criterion for infilled rock discontinuities will be discussed.
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November 12, 2008
Remote Sensing and GIS Based Materials Information Management
Henk Buys
The state’s road pavements are required to perform under increasingly severe conditions with both increasing mass limits and increasing traffic volumes. Hence there is a critical need to locate new economic aggregate sources for future work on highways in the western part of the state such as the Newell and Sturt Highways.
This presentation provides a strategy for the development of materials sources, an overview of the use and integration of various remote sensing methods for identifying potential materials sources, and GIS based data management systems for the management of these sources.