Australian Geomechanics Society Newcastle, New South Wales – 2005 Meetings

• May 23, 2005

  Surface Matching and Surface Change Detection for the Assessment of Landslides, Cliff Erosion and Mine Subsidence

  Dr Robert Paquet, Research Associate, School of Engineering, University of Newcastle

  This seminar presented surface matching techniques. Surface matching has been a topic of research for over 15 years at the University of Newcastle. The primary function of surface matching is the registration of data sets in the same coordinate system. The differences between the data sets may then be examined and assessed. Applications of surface matching include registration of data sets and deformation monitoring (landslide, cliff erosion, mine subsidence), biometrics, computer vision, and reverse engineering. An overview of different matching algorithms (ICP and surface matching) and their use is presented. The algorithm developed by the author is examined in detail, with examples and applications.

• April 20, 2005

  Reliability-based Geotechnical Design

  Prof. Gordon A. Fenton, Dalhousie University, Halifax, Nova Scotia, Canada

  In an effort to harmonize with structural codes, geotechnical design codes around the world are beginning to migrate towards some form of reliability-based design (RBD). Significant steps in this direction can be found in, for example, Eurocode 7 (2003), Australian Standards AS 4678 (2002), AS 5100 (2004), AS 2159 (1995), NCHRP Report 507 (2002) and the Canadian Foundation Engineering Manual (1992). These RBD provisions are most often presented in the form of a Limit States Design, to define critical performance states, combined with load and resistance factors which are calibrated to achieve the target reliabilities associated with the various limit states. The use of load and resistance factors is generally referred to as Load and Resistance Factor Design (LRFD).

  At this time, reliability-based design provisions in geotechnical codes are primarily based on calibration with older codes, and for good reasons - one of which is that calibration is a useful way to incorporate years of practical experience into a code. Another is that soils and their mechanical behaviour are much more difficult to characterize probabilistically than are the other quality-controlled materials commonly used by engineers (e.g. concrete, steel, wood). However, in order to take advantage of the full power of a reliability-based design methodology, the design provisions should incorporate probabilistic methods of describing soil behaviour.

  This talk traces the development of reliability-based design in geotechnical engineering, and how it has been implemented in a variety of design codes around the world. Then, some of the significant stumbling blocks to going beyond calibration from older codes and introducing some of the real advantages of a reliability-basis for design are pointed out. Finally, some of the possible ways in which reliability-based geotechnical design can be improved, and the headway being made towards these improvements, are explored in the context of common geotechnical design problems, such as slope stability, bearing capacity, and settlement.

• May 3, 2005

  AGS Newcastle Chapter Mini-Symposium — Geotechnical challenges for development in the Hunter Region

  Local practitioners

  Presentation details

• August 17, 2005

  Grading entropy variation due to soil crushing

  Dr Imre Emoke, Technical University of Budapest

  The grading entropy of a soil [S] is a kind of statistical entropy consisting of two terms. The base entropy [So] is arisen from the fact that statistical cell width (fractions) in the conventional grading curve is not uniform. The entropy increment [_S] is arisen from the mixing of the various fractions. The goal of the research is to study if any parts of the grading entropy play the role of the “true” entropy in a thermodynamic sense. For this aim the crushing process - an irreversible process having a directional property in terms of the grading curve – was considered. There is a general observation that the final state of the crushing tests can be characterised by the so-called fractal distribution. The soil samples were subjected to successive crushing treatments, the grading curve and the grading entropy were determined after each treatment. According to the results, only the entropy increment [_S] increased monotonically with an increasing number of crushing treatments. The consequence of this result is that the ultimate state is well-defined: the maximum entropy increment [_S] point which is related to such grading curves where the relative frequencies of the fractions are equal. A direct relationship between this final state and the fractal distribution was shown.

  The cone penetrometer is used for logging- and for rheological-testing. The logging test is performed by pushing continuously. The rheological test is performed in such a way that the steady penetration is stopped at any depth, the rod is kept in clamped position and the time variation of some stress variable (e.g. pore water pressure, local side friction, cone resistance, radial total stress) is measured. The duration of the rheological test may vary from 2 minutes to 1000 min. The goal is the development of some new economic rheological type CPT methods (if it is possible, without pore water pressure measurement and with very short test duration).

• September 21, 2005

  Effects of ground and air vibration on structures

  Adrian Moore and Alan Richards, Terrock Pty Ltd Consulting Engineers, Melbourne

  Adrian Moore and Alan Richards are Principals of Terrock Pty Ltd, Consulting Engineers specialising in the control of vibration due to blasting and the use of construction equipment. They discussed the transmission and attenuation of both airblast and ground vibration, significant factors affecting blast vibration, and design and control procedures. They shared their experience of the environmental and structural effect around mining and construction sites throughout Australia, summarise the current statutory requirements for the control of airblast and ground transmitted vibration in Australia, and compare these with standards set elsewhere in the world.

• October 10, 2005

  2005 Rankine Lecture: Long-Term Performance of Contaminant Barrier Systems

  Professor Kerry Rowe, Vice Principal (Research), Queen’s University, Kingston, Ontario

  Barrier systems for waste containment facilities typically include both permeable drainage and low permeability liner components and are constructed using a combination of natural and geosynthetic materials. This lecture describes the latest findings with respect to the long-term performance of these systems based on theoretical developments, laboratory studies and observed field behaviour. Consideration is given to the effectiveness of modern liners in controlling long-term contaminant transport under normal operating conditions. The lecture will then discuss techniques for estimating the service life of these systems. Field data relating to the clogging of leachate collections systems is examined and the latest techniques for predicting performance are highlighted. The impact of clogging on both contaminant migration and the service life of the liner system are discussed. The long term performance of geomembrane liners is then investigated. Finally consideration is given to the long term performance of clay liners, with particular emphasis on the potential for desiccation of the liners due to heat generated in landfills.

• October 20, 2005

  Trees and their interaction with the soil – Design of footing systems for trees?

  Don Cameron, Senior Lecturer in Civil Engineering (Geotechnical), University of South Australia

  In this lecture, Dr. Don Cameron of the University of South Australia presented current and future research into trees, both in the urban landscape and in the rural rail corridor. The water demand of trees and the impacts on soil moisture distribution was presented, as well as the beneficial impacts of soil drying on the engineering properties of clay soils. The second part of the lecture explored potential approaches to the design of footing systems for trees in the urban environment. Don was well placed to discuss this issue as a long-serving member of Standard Australias’s committee BD25 for AS2870 - Residential slabs and Footings, and as the current chairperson of the South Australian Footings Group. Footing designers in South Australia have used the Footings Group method of designing for tree drying effects with success over the last decade or so, although weaknesses in the approach are obvious. BD25 is considering incorporating general guidelines for “tree design”, and the Footings Group approach is therefore appealing, but it remains a matter of debate how transferable to other climates this method is. So the presentation also provided the opportunity for members of the local community to air their concerns.

• October 26, 2005

  Special Student Function: To celebrate the final submissions of the 4th year CIVL 4570 Geotechnical Design Projects

  Local Practitioners and AGS Committee

• November 10, 2005

  38th Rankine Lecture. Soil Characterisation: The importance of structure and anisotropy

  Dr David Hight, Geotechnical Consulting Group, London

  The design process in geotechnical engineering is reviewed to identify the role played by soil characterisation. Taking three soil types, soft clays, stiff clays and sands, the importance in practice of structure, anisotropy and natural variability are explored. Results of a numerical study and a case history are presented to illustrate the shortcomings of current design methods which fail to take into account these aspects when characterising soils.