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Finite Difference Simulation of Brumadinho TSF (By Katy O’Brien, Associate Engineer, ARQ Geotech)

ARQ recently performed advanced numerical modelling, employing critical state soil mechanics constitutive models, in support of a paper authored by John Wates which investigates the failure of the Brumadinho TSF.

The mechanism of failure postulated in the work involves progressive failure triggered by the collapse of an internal void within the TSF, originally created by the loss of slimes through a defective drilled drain.

The modelling procedure relied upon critical state soil mechanics to capture both drained and undrained, contractive and brittle behaviour. The model was set up such that elements experiencing a rapid strain-rate were switched from being controlled by drained to undrained parameters. Once undrained, it was found that strains corresponding with peak undrained strengths are surpassed and zones of tailings strain-soften and fail brittle. The yielding and brittle failure of elements then propagate in a progressive manner, triggered by the loss of confinement in neighbouring zones, until the entire side slope of the TSF fails. The mechanism observed through this modelling approach shares many similarities with the actual event per video footage of the catastrophe.

For more detail, please consult John’s paper in its original format at the link below, and have a look at the video from ARQ’s Finite Difference Model.