Accounting for brittleness in tailings storage facilities

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F22%3A00360485" target="_blank" >RIV/68407700:21110/22:00360485 - isvavai.cz</a>

Result on the web

<a href="https://nla.gov.au/nla.obj-3068565601/view" target="_blank" >https://nla.gov.au/nla.obj-3068565601/view</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Accounting for brittleness in tailings storage facilities

Original language description

Following the failures of Samarco and Feijão dams, brittle failure has become a frequently discussed topic within the geotechnical community. The post-failure review of the Feijão Dam identified that the sudden failure of the dam was caused in part by tailings exhibiting brittle behaviour. Brittle failure has also been identified to be a contributing factor in many previous tailings storage facilities failures. Of concern to the tailings community was the finding that there were no apparent signs of distress prior to the failures, which characterises brittle failure. The industry’s concern regarding the presence of brittle materials within tailings storage facilities, particularly when featuring upstream raises is evident in the requirements of the newly published Global Industry Standard on Tailings Management, which includes a requirement to “Identify and address brittle failure modes with conservative design criteria...”. This is also reflected in ANCOLD Guideline on Tailings Dams, which provides recommendations for conservative design assumptions if materials are found to be susceptible to static liquefaction which is noted to be a brittle subset of contractive materials. The ICMM’s Good Practice Guide for tailings management uses the term brittle on numerous occasions and even refers to “credible brittle failure modes” when discussing the performance-based approach. Despite its frequent use, the term brittle failure has not been defined in any of the listed references and the authors of this paper are not aware of the any clear geotechnical definition for brittle embankment failure in literature. Brittleness, on the other hand, is a well-known geotechnical parameter that describes the degree of reduction of the soil shear resistance after reaching the peak strength. Bishop (1967) described the soil brittleness in the context of progressive failure of clays by means of a brittleness index, which is the ratio of the shear resistance loss to the peak shear strength. In recent years, the brittleness index has become a common soil parameter that is used as an indicator for tailings susceptibility to liquefaction. The brittleness index does not consider the rate at which the soil resistance reduces, and it ignores the stress strain relationship. As a result, the same brittleness index can be calculated for a soil that collapses over a very small strain range and a soil that gradually reduces its shear resistance over extensive strain levels as long as both soils have similar peak and residual shear strengths. This paper discusses the root causes of brittle behaviour of tailings, summarises the current approach for brittleness assessment and recommends considerations and methods to assess and deal with potentially brittle soils within TSFs.

Czech name

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Czech description

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Type

D - Article in proceedings

CEP classification

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OECD FORD branch

20701 - Environmental and geological engineering, geotechnics

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Article name in the collection

ANCOLD 2021 Dams : perceptions of realities or risk: event proceedings, full papers

ISBN

9780648543954

ISSN

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e-ISSN

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Number of pages

398

Pages from-to

1-398

Publisher name

AUSTRALIAN NATIONAL COMMITTEE ON LARGE DAMS (ANCOLD) INC

Place of publication

Sydney

Event location

Perth, Western Australia

Event date

Nov 10, 2021

Type of event by nationality

WRD - Celosvětová akce

UT code for WoS article

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