Australian Geomechanics Society South Australia & Northern Territory – 2000 Meetings

• February 7, 2000

  1999 E. H. Davis Memorial Lecture: Embankment Dams - Some Lessons Learnt and New Developments

  Prof. Robin Fell

  The lecture described some personal experience accumulated over 33 years of working on embankment dams as an investigations and design engineer, review consultant and supervisor of research. The issues covered included:

  • Seepage in dams and their foundations.
  • Internal erosion and piping failure, including filter design, and the factors which influence the initiation, and progression of piping leading to breach of the dam.
  • Stability and deformation behaviour, and "aging" of dams.
  • The role of Quantitative Risk Assessment in dam safety management.
• March 20, 2000

  Site Visit - Linwood Quarry

  Gus Harvey

  The site visit included a tour of the Linwood Quarry near Marino.

• April 17, 2000

  Design of Large Underground Excavations

  Dr. Tony Meyers

  In Australia, large underground excavations for Civil Engineering purposes have traditionally been associated with hydroelectric installations. However, these excavations are now becoming more common and will continue to do so. In the mining industry, large underground excavations are common and many of the principles used and rock mechanics issues considered when designing these excavations are becoming relevant to Civil Engineers and Engineering Geologists. In addition, many of these professionals are considering working within, or consulting to, the minerals industry as a career path and a knowledge of the terminology used, and techniques applied in, the industry can be useful. This lecture will introduce the basic principles involved with the construction and empirical design of large underground excavations in rock for the mining industry. Based around case studies, the presentation discussed some of the challenging issues that must be considered such as anisotropy, scale effects, variability and in-situ stress. It also considered the use of probabilistic techniques in the design process.

• May 8, 2000

  40th Rankine Lecture Nonlinear Soil Stiffness in Routine Design

  Prof. John Atkinson

  Over the past 30 years or so the fundamental non-linear stress-strain behaviour of soils and soft rocks has been established by laboratory and in situ tests leading to development of new theoretical models for soil behaviour and complex numerical analyses. But for much day-to-day practice, ground engineers do not need such complex and detailed methods and they commonly employ simple routine calculations. These use either a factor of safety, or load factor, so that movements are limited, or a single stiffness modulus in a simple elastic analysis. The choice of an appropriate load factor or stiffness modulus depends to a great extent on the characteristics of the non-linear stress-strain behaviour of the soil.

  Soil parameters which can be measured simply and reliably are the strength and the strain at failure which can be related to initiation of shear bands or slip planes and the stiffness at very small strain which can be determined from measurement of the velocity of shear waves. These parameters lead to a simple concept of degree of non-linearity which guides choice of load factor or stiffness for routine design.

  The lecture explored how new knowledge of non-linear soil stiffness and development of relatively simple soil tests can lead to logical choices of load factor and stiffness modulus for use in routine analysis of common geotechnical constructions.

• June 19, 2000

  Remediation of Contaminated Sites

  Adam Kilsby, Andrew Piggin, Mike Fanning

  Contaminated Soil - Take it or Leave it (Adam Kilsby)

  The viability of redeveloping 'brown fields' sites within South Australia can be significantly influenced by residual soil contamination associated with past land use. The viability is particularly relevant for residential developments on former commercial/industrial sites, where changing the land use to one more sensitive can introduce additional costs to facilitate planning consent. The economic success of developments that require remediation is largely dependent upon the management of the contamination issues, including the timeliness of obtaining soil data, the method of remediation, and the land value after remediation. This presentation discussed: the advantages of considering environmental and geotechnical issues concurrently; examples of recent residential developments in Adelaide that included remediation of soil contamination; and the pros and cons of leaving contamination on site compared with removing it.

  Halifax Street Decontamination (Andrew Piggin)

  The Halifax Street development project, on an ex-industrial site in the heart of Adelaide, will involve a staged construction of mixed dwellings of two and three storey townhouses over part of the site and a series of three to five storeys high apartment buildings on the remainder of the site. The talk covered the history of the site, which presented some interesting challenges when subsequently deciding how to handle the soil at the site. The soil was eventually removed in an environmentally sensitive manner given the site's close proximity to residents and schools.

  Site Contamination, Assessment and Remediation, an EPA Overview (Mike Fanning)

  The presentation defined Site Contamination and provided an overview of the key current processes for the management of site contamination in South Australia. The presentation was aimed at environmental and geotechnical engineers/consultants to ensure that site contamination is appropriately addressed for all developments in South Australia. The processes for assessment and remediation of site contamination were covered by reference to the National Environment Protection (Assessment of Site Contamination) Measure, the current regulatory context and the proposed Site Contamination Bill.

• July 17, 2000

  Application of Pressure Injection

  John Adamson

  This presentation discussed a number of geotechnical projects in which the Pressure Injection Process has been used. These projects include railway and road stabilisation and contaminated ground remediation. According to the contractor, the range of uses for the process are limited only by the imagination. The presentation also presented some procedures that, although not yet attempted, highlight the potential future direction for the process.

• August 24, 2000

  Case Studies in Geotechnical Engineering (Joint Meeting with the S.A. Footings and Structural Groups)

  Various

  Assessing the Performance of the Footings on the Commercial Road Railway Viaduct at Port Adelaide, Richard Herraman

  The loads on transport infrastructure are continually increasing. How can we determine whether the footings of old bridges will perform satisfactorily under proposed load increases? What is a cost to effectively upgrade the footings? We also know that footing design methods used in the past were often conservative. All this justifies a careful assessment of existing footings when increased loads are proposed.

  Footing Solution for the Burswood Resort Extensions, Perth, Peter Mitchell

  The $75 million extensions to the casino and convention centre at the Burswood Resort in Perth, WA involved construction over reclaimed land on very soft Swan River Valley alluvial soils. The project offered the challenge of requiring precast concrete piling to be driven to depths of the order of 36m without any vibration and with minimal noise. The commercially available 'G-pile' from Australasian Piling Company was found to successfully meet these challenges. Dr Mitchell will outline the results of soil testing and the geotechnical conditions, the pile design, and the pile construction and installation.

  Soil Nailing, Paul Gunson

  Soil nailing was selected as the method to stabilize the steep river bank below the footpath on the river side of Adams Street, Hindmarsh after longitudinal cracks were noticed in a section of footpath above the steepest part of the bank. The method was adopted because it offered a solution, which would have a minimal disruption of the traffic in Adams Street during construction; would have minimal effect on the river flow; could be constructed in a relatively safe environment; and would be economical. Mr Gunson will describe the design process, the construction process, the changes to design as the true site conditions were revealed, and the successful completion of the project.

• September 18, 2000

  Annual Half-Day Seminar - Recent Developments in Piling

  Various

  • Prof. Harry Poulos: Recent Developments in Piling and Ground Movement Around Piles
  • Ray McMillan: 50 Years of Piling
  • Peter Mitchell: Site Investigation and Assessment of Piling Options
  • Paul Moritz: Piling Specifications: Good and Bad
  • Slav Tchepak: Developments in Concrete Injected Piles
  • Nicholas Morgan: Piling for the Pelican Point Project
  • Michael Vadasz: The G-Pile System
  • Prof. Harry Poulos: Design of Piled Rafts
  • Jonathan Cannon: Non-Destructive Pile Testing
• October 16, 2000

  Young Geotechnical Engineers Night and Annual General Meeting

  Neil Schunke, Chris Hughes, Klayton Stivers, Julianne Martin, Nigel Brooks

  Five young geotechnical engineering graduates and students individually gave a 10 minute presentation on a range of interesting projects. Members of the Committee adjudicated that Klay Stivers, URS, Adelaide was the winner was presented with a certificate and a $250 cash prize.

• November 16, 2000

  International Speaker: Application of Limit State Principles to Geotechnical Problems

  Brian Simpson

  Eurocode 7, on Geotechnical Design, is one of a suite of 9 European codes for the design of buildings and civil engineering structures. Work on Eurocode 7 started in the early 1980s, and it was published as a draft for development in 1995. A final version is due for publication in 2001. It is intended that the Eurocodes will be mutually consistent documents, and this has set a major challenge to geotechnical design, since the interface between geotechnical and structural design codes has been confused in many nations, including the UK. The Eurocodes are based on a limit state method, with safety margins generally provided in the form of partial factors. Eurocode 7 sets out the use of a partial factor approach to geotechnical design in a context of sound geotechnical engineering. It attempts to define the process by which parameter values will be selected for calculation, from the usual sparse and scattered data available to engineers. In separate sections, it then details the application of this approach to typical foundation types, retaining structures and slopes.

  The talk described the contents of the code and presented some of the more important, and controversial, features of its methods. These were illustrated by examples of both foundations and retaining structures. Likely changes between the 1995 draft and the issue planned for 2001 were also discussed.

• December 4, 2000

  Visitors Night, Belair Bhavan Tandoori Indian Restaurant

  Mark Elford

  Each year, the last meeting is devoted to a social event where members and others are encouraged to bring along their wives and partners for a fine and inexpensive meal. The evening includes a non-technical presentation.