Australian Geomechanics Society South Australia & Northern Territory – 2003 Meetings

• February 17, 2003

  Annual Field Trip: Port River Expressway

  David Bartlett, Richard Cavagnaro

  Construction of Stage 1 of the Port River Expressway is underway. When complete this project will contribute to South Australia's economic development by providing new road, rail and bridge connections across the Port River, linking our export enterprises and industrial areas with key transport routes and facilities. It will also contribute to the ongoing development of the Port Adelaide area. During this trip we will inspect several sites on the proposed alignment and David Bartlett, Transport SA's Project Manager for Stages 2 & 3 of this project, will address us on these issues. The alignment tranverses low lying country underlain by loose sand and soft clay , with a high groundwater table and subjected to uncontrolled filling. Richard Cavagnaro, who has performed much of the geotechnical and contamination investigation for this project, will address us on ground conditions and the challenges they pose for this project.

• March 11, 2003

  Ground Improvement Techniques

  Trevor Osborne

  Various geotechnical methods have been employed to alter the properties of soils in order to provide enhanced capacity to support "structures", as an aid to excavation or for other purposes such as reducing water flows. These methods include vibro compaction, vibro replacement, dynamic compaction, explosive compaction, soil mixing, grouting, pre loading, sand or wick drains and soil reinforcement. The object of improvement may be to increase strength, to reduce settlement or deflection or to change the soil permeability. In many instances the use of ground improvement may result in considerable cost savings compared to more conventional structural solutions such as piling. This presentation gave a general description of various ground improvement techniques along with selected examples from Trevor Osborne's experience spanning a period in excess of 30 years. Examples presented included:

  • stone columns loaded to over 600 kPa
  • use of vibroflotation as an aid to excavation
  • some recent applications of jet grouting
  • and grouting of mine waste to minimise settlement.
• April 15, 2003

  Collapsing Cones, Slippery Slopes, Hot Ground, Titanic Topples, Dams and Development: Engineering Geological Challenges and Models for the Active New Zealand Environment

  Dr. Warwick Prebble

  New Zealand is a highly varied landmass with many different terrains displaying defective and difficult rock and soil masses crafted by a collection of hazardous geologic processes. This presents a unique challenge to engineering development. This talk offers a personal view of the contribution engineering geology has made to our understanding of this active New Zealand environment drawing on 35 years of experience in field-based research on engineering projects. Examples were presented from a wide range of hazardous terrain as introduced below. Very large clay matrix debris flows from hydrothermally altered and collapsing active andesite volcanoes are a potential geotechnical hazard, but their deposits have provided very useful dam foundations and reservoir containment. Thermally weakened fault scarps release large debris flows every 1200 years in the centre of the Taupo Volcanic Zone. Geothermal fields spontaneously erupt, including those in the suburbs of Rotorua City and others can be overrrun by landslides, promoting further instability. Clay seams give rise to slides in weak tabular rock masses throughout the Auckland region and elsewhere in the North Island and highly sensitive rhyolitic silts are being found as basal ruptures in terrace deposits well outside the volcanic zone in the northern North Island. Toppling of very large masses of greywacke and schist is widespread in the South Island, in dip slopes as well as scarp slopes. Deep-seated bending surfaces in dip slopes has given rise to catastrophic rock and debris avalanches. Overtoppling of this type is not widely recorded but is turning out to be a significant rock mass failure mode, especially in the rapidly uplifting steeplands.

• May 12, 2003

  Slope Stability Forum

  Dr Peter Mitchell, Dr Tony Meyers, Dr Ahmed Soliman, Richard Cavagnaro, Richard Herraman

  When you are confronted with a slope stability problem do you have difficulty in determining degree of slope hazard and failure mechanism? Even when you've got a handle on these, you've still got to work out the best method for reducing slope hazard to a suitable level and design the remediation (including determining soil strength parameters). Not only all this, but you've got to deal well with your client. Feeling daunted ……you are not alone. This meeting featured brief presentations about a variety slope stability problems and touched on these issues.

• June 23, 2003

  Brownfield Britain - Recent Experiences With Contaminated Sites in the UK

  Derek Avalle

  Over the last few years, the UK has seen some very significant changes in environmental legislation. In particular, this has affected the manner in which contaminated land assessment is undertaken and, consequently, the type of remediation approach that gains acceptance. Concepts such as suitability for use and harm now drive the assessment process in the UK, and quantified risk assessment is generally applied. Derek's presentation outlined some facets of the evolution of the contaminated land regulatory regime in the UK. Drawing from a wide range of project experience, he highlighted a selection of examples that illustrate the range of issues that are posed by the reuse of former industrial land, some sites having a history of many centuries, as well as some remediation techniques that are being applied in the UK at present.

• July 14, 2003

  Annual Half-Day Seminar: Salinity

  Various

• August 16, 2003

  Geotechnical Challenges and Solutions in Vancouver, British Columbia, Canada

  Don Richardson

  Vancouver is one of the most beautiful and livable cities in the world and is an important port and centre for commerce and tourism. The geography and geology also make it an exciting and challenging place for geotechnical professionals. The last ice age (as little as 8,000 years ago) covered the region with a thickness of hundreds of metres of glacial ice. The geography and geology of Vancouver includes the legacy of glaciation, together with extensive weak and compressible alluvial sediments from the delta of the Fraser River (a river with a catchment size similar to that of the Murray Darling Basin). The risk of ground movements associated with earthquakes is also an important geotechnical consideration for projects in cities like this on the Pacific coast of North America. Don's presentation included an overview of the geological setting of Vancouver. He also discussed the associated ground engineering risks, challenges and geotechnical solutions using examples from projects including port infrastructure, waterfront development, emergency services, commercial developments and roads. Don worked as a geotechnical engineer in the Vancouver office of Golder Associates between 2000 and 2002. The opportunity was part of the Golder Associates international employee exchange program. Don has over 10 years of experience with Golder Associates.

• September 8, 2003

  Alice Springs to Darwin Railway - The Engineering & Construction Issues

  Tony Dawson

  This presentation included track design, earthworks, hydrology, hydraulic design of culverts, structural design of culverts, minor and major bridges. Note that ease and efficiency of construction and logistics were a strong driver of the design approach.

• October 13, 2003

  Young Geotechnical Engineers Night and Annual General Meeting

  Brendan Scott, Tom Forde, Jason Goldsworthy

  In 2003, three young geotechnical engineering graduates and students individually gave a 10 minute presentation on a range of interesting projects. Members of the Committee adjudicated that the 3 presenters were all worthy winners of the Award and they were each presented with a certificate and a $100 cash prize.

  Brendan Scott, Witton Bluff Stabilisation

  Brendan will share his experience from working on the stabilisation works at Witton Bluff. Brendan has been involved in the design process of the stabilisation works, as well as in the role of Project Manager, Superintendent and Site Engineer during the construction phase. His presentation will cover project background information, design issues and considerations, problems encountered during construction and lessons learnt from the project. Brendan graduated with Honours from the University of Adelaide in 1999; has been an employee of Parsons Brinckerhoff since February 2000, and has worked in the field of Geotechnical Engineering for nearly two years.

  Tom Forde, Groundwater Management Investigation using Geophysical and Hydrogeological Methods at Pasminco Port Pirie Smelter

  URS was involved in a groundwater management investigation for Pasminco Port Pirie Smelter at Port Pirie, South Australia to assess the feasibility of using a central dewatering system to manage the offsite discharge of contaminated groundwater. Works centred on a low-lying area of the smelter site excavated into poured slag referred to as the 'Amphitheatre Pit'. The investigation required the characterisation of groundwater behaviour with respect to flow rates and interaction between natural and slag aquifers and potential tidal influences. Key project activities were a magnetic survey of the area to attempt to locate greater thicknesses of poured slag, and pumping tests to correlate the findings of the survey to available volumes of groundwater. Geotechnical design issues included the magnetic survey and its interpretation, selection of pumping test sites and incorporating these in an overall groundwater management strategy for the site. The outcomes of the investigation provide an interesting example of environmental geotechnics in practice.

  Jason Goldsworthy, Quantifying the Risk of Site Investigation

  Inadequate site investigations can either lead to foundation failures or costly overruns and time delays. However the scope of a site investigation is typically dependent on the budget and time constraints placed on the geotechnical professional. Furthermore, there is currently limited to no information regarding the relative risk of undertaking site investigations of varying scopes. Consequently, a methodology has been developed to quantify the probability of failure or overdesign as well as the financial risk of undertaking site investigations of varying scope. This presentation covered the framework used to assess the influence of site investigations on the design of foundations, in particular, pad footings, as well as some early results obtained from it.

• November 10, 2003

  Visitors Night: The life of a peasant winemaker in the Adelaide Hills or An insight into the insanity required to run a micro-boutique winery in the Adelaide Hills

  John Venus

  Held at: Bistro 49, 49 Mt Barker Road, Stirling. John describes himself as Vineyard Manager / Hand, Winemaker, Cellar Hand, Office Manager, Advertising Executive, Chief Bottler and Labeller, Packer, Despatch Officer, Transport Coordinator and Driver of Arranmore Vineyard. John talked about the philosophy that led him to make wine and the reasons behind the types of wine he produces. The talk concentrated on how he makes his wines and their character.