Australian Geomechanics Society Newcastle, New South Wales – 1997 Meetings

• April, 1997

  Stress-Deformation Behaviour of an Embankment on Boston Blue Clay

  A/Prof Andrew Whittle, Dept Civil & Environmental Engineering, Massachusetts Institute of Technology

  An 11m high embankment was thoroughly instrumented with piezometers, settlement rods and inclinometers to measure the behaviour of the underlying 40m thick deposit of Boston Blue Clay during staged loading and four years of subsequent consolidation. estimates of the engineering properties of the clay were made based on in-situ testing and laboratory test programs. Finite element analysis was undertaken incorporating coupled consolidation with two generalised effective stress soil models (Modified Cam Clay and MIT-E3). Comparisons of predicted versus measured performance during 1963-1973 are presented.

• June, 1997

  Discrete Element Modelling in Soil Mechanics

  Dr. Stephen van Baars, Postdoctoral research Fellow, University of Sydney

  An alternative to the Finite Element Method, the Discrete Element Method is particularly suitable for modelling granular materials and for studying the relationship between `micro' and `macro' behaviour. Discrete Elements allow contacts between elements to be created or broken and can therefore be used to gain insight into the processes of nucleation and growth of a crack. Current research at the University of Sydney will also be discussed, namely a project aiming to improve our understanding of failure mechanisms of underground openings in jointed rocks and to predict failure loads.

• September, 1997

  Three Dimensional Boundary Element Analysis Of Stress At Lkab Mine, Kiruna, Sweden

  Dr John Watson, Department of Mining Engineering, University of New South Wales

  Mining of iron ore at Kiruna by sub-level caving is now at a depth of 500m below the surface, and stress related problems are being encountered. The purpose of the present investigation is to estimate the the stresses around the drawpoints from which fragmented ore is recovered. The rock may reasonably be taken to be isotropic and linearly elastic. The difficult aspects of the analysis are the need to carry out a mine-scale analysis to obtain results at a one metre scale, and the effect of error in determination of the pre-mining stress field.

  Boundary elements of finite and infinite extent with quadratic variation of displacement are used. In a first analysis, the global redistribution of stress around the mine is computed. Results given by this analysis are then taken as input to a more detailed analysis of the part of the mine for which results are required at the one metre scale.

  Preliminary results indicate that it may be possible to reduce the incidence of stress problems by careful attention to the sequencing of ore extraction. More definite conclusions cannot be drawn until uncertainties in the pre-mining stress field are resolved, probably by comparison of failures observed underground with those predicted by boundary element analysis rather than by further measurements of stress in the filed.

• December, 1997

  A General Discussion Of Constitutive Models For Soils

  Professor Gerd Gudehus, University of Karlsruhe, Germany

  Constitutive modelling of soil remains a topic of considerable debate in Geotechnical Engineering. The speaker addressed some of the important issues in developing useful constitutive models.