Australian Geomechanics Society Victoria – 2003 Meetings

• March 19, 2003

  Eureka Tower, A Bored Pile Foundation Story

  Max Ervin

  The Eureka Tower Project is a 300 m high 88 level residential building, being constructed in the Southbank precinct of Melbourne, Australia. The site is underlain by complex geology, including near surface soft clays, a shallow layer of Quaternary Age basalt which covers part of the site, a lower very high strength basalt layer at about 20 m depth and again covering only part of the site, with high strength Silurian Age siltstone as the basement rock at about 30 m depth.

  Unusually extensive site investigations were undertaken for the project due to the complex geology. Piled footings were required, but due to the very high strength of the lower basalt (UCS up to 250 MPa) it was desirable as far as practical to found on this material. A hybrid piling solution was developed, with 750 mm diameter CFA piles founding on the lower basalt over part of the site, and 1.2 m diameter bored piles socketed into the siltstone used elsewhere. Two CFA test piles were constructed, with Statnamic and dynamic load tests then performed. Dynamic testing was then undertaken on a number of the prototype piles.

  The bored piles were designed to accommodate working loads of up to 22 MN. An allowable base resistance of up to 20 MPa was considered acceptable for the very high strength siltstone. However, settlement compatibility with the CFA piles founding at shallower depth on the basalt was necessary. The adopted socket in the siltstone was therefore based on predicted settlement, with the socket length assessed using the program ROCKET.

  The talk will describe this case history.

• April 14, 2003

  Poulos Lecture 2003
  Collapsing Cones, Slippery Slopes, Hot Ground, Titanic Topples, Dams and Development: Engineering Geological Challenges and Models for the Active New Zealand Environment

  Dr Warick 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 are 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.

• April 30, 2003

  Deep Foundations – Queen Vic Site

• May 21, 2003

  Queen Victoria Village Project – Temporary & Permanent Ground Support

  Peter McDonald, Adam Lander, Michael Broise

  The new Queen Victoria Village currently being developed occupies an entire city block, with a deep basement extending to a maximum depth of 22m. The basement area is approximately 100m x 200m. It represents one of Melbourne’s largest basement excavations. The ground conditions comprise variably weathered siltstone of the Melbourne Formation, intersected by weak dykes. The excavation was adjacent to two significant masonry structures.

  Conventional basement support in these conditions consists of tensioned cable anchors through soldier piles installed prior to excavation. For this project consideration was given to an alternative form of excavation support using untensioned rock nails, progressively installed as excavation proceeded. This form of support requires detailed consideration of the mass strength behaviour of jointed rock. Peter McDonald will describe the investigation, design, construction and monitoring aspects involved in using rock nails for some wall sections of the basement. A significant complication during basement works in the south–east portion of the site was the occurrence of a massive weak dyke structure. The influence of this feature on design and construction is discussed.

  Adam Lander will present an overview of Coffey’s involvement with the QV Project as geotechnical advisor to the builder. Topics to be addressed will include permanent support for the excavation and foundation solutions adopted for the considerable structural loads. Of particular interest will be the support measures taken, and the monitoring and the performance of two significant adjacent masonry structures, the Women’s Centre and the State Library of Victoria.

  Michael Broise will present an introduction of the project with reference to the geological setting and description of the major dyke.

• June 18, 2003

  Recovery of the World Trade Centre Basement New York

  George Tamaro, Dr Bill Bamford

  In 1967 the Port Authority of New York and New Jersey undertook the construction of the World Trade Center (WTC) complex, consisting of seven buildings on a 65,000 square metres site in New York City.

  The deep basement (bathtub) portion of the site covers an eight–city–blocks area (330m by 165m), some 60 metres from the east shore of the Hudson River. The Manhattan Schist bedrock was found.

  The Manhattan Schist bedrock was found at depths of 17 to 23 m below the surface, overlain by glacial outwash sand and silt, or soft organic marine clay (river mud). Groundwater levels were within 2 metres of ground surface. The basement was bounded by a 1000m long, 900mm thick diaphragm wall constructed from grade and socketed into bedrock. 1,500 high–strength tendon tieback anchors were installed to provide lateral support of the wall as the excavation proceeded downwards. Tieback anchor capacities varied from 100 to 300 tonnes. Once the permanent basement floors were completed, the tieback anchors were detensioned. On 11 September, 2001, the WTC was destroyed by terrorist attack.

  The below grade recovery effort at the WTC began shortly afterwards. George Tamaro, who worked on the original construction of the diaphragm wall, was engaged to supervise its recovery, the reinstallation of tieback anchors, and the stabilization of the site. He has graciously agreed to his Powerpoint presentation to be delivered on his behalf, by Bill Bamford.

  Following the completion of the WTC recovery effort on September 2002, PBS made a video record of the entire project. The portions dealing with the basement recovery and wall stabilization will be shown.

• July 9, 2003

  Joint Seminar with Structural Engineering Branch
  Inadequate Site Investigation – What are the real costs?

  In civil engineering and building projects, the largest element of technical and financial risk is normally in the ground. Inadequate site investigations commonly lead to a range of undesirable project outcomes including inappropriate engineering design, cost over-runs, construction delays and contractual disputes. Yet, many projects proceed on the basis of inadequate site investigation and with limited input from geotechnical professionals. Clients need to be educated to the risks and cost penalties associated with this practice. These materialise as conservative designs and an inability to plan, manage and execute the project successfully.

  This seminar presents a review of the state of current practice, an overview of documentation currently available to assist those in advising clients and engaging geotechnical investigations, a range of examples and views from across the construction industry on the impacts of ground investigation on project outcomes, and a discussion of strategies for addressing this significant problem.

  • Neil Benson – Adequate Ground Investigation?
  • Ben Collingwood – Site Investigation for Piling Projects – The False Economy of a Cheap Investigation.
  • Peter Tilley – Investigation and preparation of working platforms for safe and efficient piling.
  • Slav Tchepak – Impacts of Site Investigation on Piling Projects – Case Studies.
  • Reg Hobbs – Concept level cost estimate - Is the cost of preliminary geotech worthwhile?
  • Peter Megens – Legal Issues – Insurance
  • Andrew Goad – A Structural Engineers Perspective
• August 20, 2003

  Ports and Harbours

  Venket Naidu – Sheet Pile Wall Applications Around Ports

  Maritime civil engineering covers a wide range of structures and earthworks ranging from bulkheads, suspended deck on piles, various types of reclamation, breakwaters and other coastal protection works, dredging and coastal processes. These structures are subject to dynamic loads from wind, current and waves as well as vessel impacts. A good understanding of the interaction between the soil and the structure in such environments is critical for safe and cost effective design.

  In this presentation the following two types of maritime projects will be briefly discussed together with the critical design issues and how they were addressed:

  • Review the stability of wharf structure and investigate upgrade options for retro-dredging
  • Piled wharf and access jetty in widely varying rock profile

  Ian Pedler – Investigations for channel dredging in Port Phillip Bay

  Port Phillip Bay comprises relatively shallow areas around the edges and entrance to the bay that have required the construction of channels to allow shipping movements to berths in Geelong and Melbourne. Over time the channels silt up and need maintenance dredging to restore the draft clearance for vessels. In 2002, the Victorian Channels Authority commissioned geophysical and geotechnical investigations for the maintenance dredging of the Port Melbourne and South Channels. Coffey Geosciences Pty Ltd carried out the investigations which involved underwater seismic refraction and reflection surveys and geotechnical drilling from a jack up barge under the superintendence of SKM. Mr Ian Pedler, a Principal of Coffey, will describe geophysical studies, the drilling investigation and laboratory testing that were carried out as part of the geotechnical studies. Mr Geoff Atkins (Manager Maritime) of SKM, will describe the conditions encountered during dredging and compare them to the expected behaviour based on the results of the investigation program.

• September 11, 2003

  Earthquake Seismic Design of Earth Structures

  Gary Gibson

  Over the past few years there have been many developments in the estimation of earthquake hazard due to earthquake ground vibration. Among the topics to be discussed will be recent developments in the definition of earthquake source regions (including active faults), improved methods of quantifying the seismicity in these regions, developments in spectral attenuation functions, methods of dealing with sites having soft surface sediments or steep topography, and practical ways of computing ground motion recurrence by including some information about the structure to be designed.

  Dr Gamini Adikari

  Gamini will discuss the use of seismic parameters in embankment dam engineering. He will explain the ANCOLD guidelines as applied to seismic assessment of dams and present a case study on a dam rehabilitation project to illustrate them.

  Dr Edward Kavazanjian, Jr

  The U.S. Federal Highway Administration (FHWA) has recently published the new draft “Guide Specifications for Seismic Design of Highway Bridges”. Dr Kavazanjian will briefly outline the new design requirements, focusing on their advantages over current requirements, and then discuss in more detail the foundation and liquefactions design provisions.

• October 9, 2003

  Soil Improvement/ Grouting

  Trevor R 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 and wick drains and soil reinforcement The objet of "improvement" may be to increase strength, to reduce settlement or to change 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 will give a general description of various ground improvement techniques along with selected samples from Trevor Psborne's experience spanning a period in excess of 30 years. Examples to be presented include:

  • stone columns loaded to over 600 kN/m²;
  • use of vibro flotation as an aid to excavetion; and
  • grouting of mine waste to minimise settlement.
• November 13, 2003

  AGM followed by Chairman's Address and Annual Dinner

  Andrew Campbell–Proposal to Move Education Forward

  Andrew Campbell will discuss the role of the AGS in continuing professional development for geo–professionals and outline proposals for an extension course for 2003.

  Ian Plymer–Annual Dinner After Dinner Presentation: Greenhouse–a load of hot air

• November 16, 2003

  Field Excursion Royal Park

  Andrew Campbell

  The railway cuttings in Royal Park provide type exposures of the Tertiary materials and their contact with the underlying Melbourne Mudstone. The cutting at Manningham St provides exposures of the Green Gully limestone member and Older Volcanics. The cutting near Royal Park station provides a full exposure of the Brighton Group contact with the Melbourne Mudstone. Background information and details on geological and geotechnical properties will be discussed at the AGS technical meeting on 13 November 2003 (refer separate flyer).

  The excursion will be lead by a number of experienced geologists including Bernie Joyce, Rob Wilson and Michael Broise. The two cuttings and drill core will be viewed with opportunities to map the exposures and discuss the engineering implications of the different materials.

• September 17, 2003

  Investigation and Monitoring of a slow moving Landslide at The Dell, Clifton Springs

  Allan Garrard, Tony Miner

  The Dell is a natural coastal amphitheatre located on the northern coast of the Bellarine Peninsula. The closure of the Dell area, is due to the ongoing development of a large-scale landslide at the site. The first telltale signs of the landslide were initially noticed in October 2001, with the observation of a large tension crack on the upper slopes of the natural amphitheatre of the Dell.

  Emergency response protocols and an extensive site management planning were initiated and all site work has observed strict working practices.

  Field investigations have included drilling, permeability testing, and the installation of a number of inclinometers and piezometers.

  Regular movement and pore water pressure monitoring has been conducted over the last year. The ongoing inclinometer readings were crucial in the assessment of the probable mode or modes of failure at the site and the inclinometer results, in particular, allowed the conceptual design of short term remedial works options.

  The comprehensive data has allowed trends to be identified with interesting outcomes.

• October 8, 2003

  Tailings Management

  Doug Sceney – Draft guidelines for management of tailings storage facilities

  The talk will provide an outline of the Draft Guidelines for Management of Tailings Storage Facilities. The guidelines have been developed over the last two years with input from a wide range of stakeholders. They address aspects of tailings management including facility design, construction, operation and closure, and are intended when finalised to provide detailed guidance on Victorian requirements for the activity. The then Department of Primary Industry has released the draft guidelines for public comment until 1 December 2003.

  Keith Seddon – Aspects of the design of tailings management facilities

  Australian Tailings Consultants provide a diverse range of tailings managerial services and are currently responsible for design and construction of several international projects.

  Keith will talk about the various tailings management methods available and the advantages to mining companies of some of the innovative methods.

  Keith will also discuss some of the aspects of tailings testing, the measurement of critical parameters, the prediction of tailings behaviour and effects these have on facility design.

• November 18, 2003

  AGM followed by 2002 Karl Terzaghi Lecture and Annual Dinner

  Victor Milligan – 2002 Karl Terzaghi Lecture - Some Uncertainties in Embankment Dam Engineering

  In the design and construction of embankment dams, our current capability for precise mathematical analysis and modeling of induced stresses and deformations, or of potential seepage patterns, far exceeds our capability to make judgments of comparable accuracy concerning, for example, the site and geology or how the soil properties may be affected by the weather or by the contractor's methods. In addition, there is often a lack of adequate communication between the design and the supervision of construction. These uncertainties or doubts about the actual performance of the dam when constructed are discussed in the presentation and illustrated by case history examples, with particular reference to the uncertain effects of cold weather, to the use of broadly graded soils (tills) as core and to problems in the placement, and segregation of tills and filter materials.

  The original presentation of the lecture, at the A.S.C.E Annual Meeting in Washington D.C. in November 2002, will be shown, via a videotape made at the time. Diagrams and illustrations referred to by the speaker will also be concurrently displayed. Copies of the recently-published 2002 Karl Terzaghi Lecture will also be made available.

  Associate Professor Ian Donald – A Melbourne Icon Re-evaluated

  Commencing with a Melbourne engineering 'icon' the presentation may soon veer into areas where a very different definition of the word applies. However after a colourful and sometimes unbelievable journey a return to a more comfortable and secure home base will hopefully be achieved.