Volume 60, Number 4, Editorial, News and Introduction

Tailings geomechanics are undergoing a period of significantly increased activity and attention owing to a series of recent catastrophic failures of tailings storage facilities and the regulatory and industry response to these events. This increased attention to tailings geomechanics can be seen in increased participation in forums and conferences internationally.

This themed edition of Australian Geomechanics was planned to provide a forum to capture some of these developments from both industry and academia. The strong embrace of critical state soil mechanics (CSSM) by the tailings industry is clear from the edition, with six of the ten papers explicitly making use of and/or measuring the critical state line (CSL) of tailings in their analyses.

Of the works utilising CSSM, Contreras et al. present techniques to more rationally select parameters for the popular NorSand constitutive model, building on an increased prevalence for such rigorous parameter selection processes in the numerical modelling community. This form of calibration provides the opportunity to increase objectivity in the selection of a numerical model.

Lines and Llano-Serna carry out cone penetration testing and laboratory characterisation to examine the in situ state of mud farmed tailings, demonstrating the effects of deposition processes resulting dilative or contractive conditions. Rodrigues et al. provide a summary of a series of laboratory tests carried out on a gold tailings from Brazil, including in situ compaction data, and hydraulic conductivity and CSL results. Shen and Jefferies numerically assess the dilatometer test to enable improvement of DMT-based correlations with insight from the numerical results, with a particular emphasis on geostatic stress ratio. Llano-Serna et al. provide a summary and examples of the material point method (MPM), a numerical approach finding increased application in helping to understand tailings dam breach characteristics. Chan and Gu outlined the use of numerical modelling to assess triggering mechanisms of an upstream raised tailings storage facility (TSF), while proposing an alternative means to calculate Factor of Safety in such cases.

In other works in this themed edition, Piccolo et al. present a series of case histories on the repurposing of TSFs, important work to highlight given the need to create safely closed facilities. Swarbrick provides an analytical solution for 1D large strain consolidation for use in predicting final density, an important analysis in the calculation of storage capacity of TSFs. Naeini et al. outline the characterisation of a tailings with particular focus on use of the Medusa flat plate dilatometer, including a focus on means to obtain high quality results in intermediate soils such as tailings. Finally, Herza and Fellows-Smith examine issues around Probability of Failure (PoF) and Factor of Safety, proposing a new method to estimate slope PoF.

It is hoped that this themed edition provides a useful snapshot of developments in tailings geotechnical engineering in practice and research. Each paper published in this themed edition of Australian Geomechanics was peer reviewed in accordance with the standard practice of the Australian Geomechanics editorial board. The editors would like to thank the many authors that contributed to this themed edition as well as the reviewers who kindly donated their time and enabled the paper review process to be completely in a timely manner.