Fundão Mine Tailings Dam Failure

This case study on the Fundão Mine tailings dam failure, has been prepared solely by GDS following its review and interpretation of the publicly available technical report. This case study briefly summarises some of the many geotechnical engineering findings reported by the panel. Specifically, it focuses on aspects of the advanced laboratory testing programme conducted during the investigation, which employed an advanced cyclic direct simple shear apparatus designed and manufactured by GDS Instruments.

Introduction

At 3:45 pm on the 5th of November 2015, the 110 m tall Fundão Tailings Dam, located in the south-eastern Brazilian State of Minas Gerais, collapsed in a liquefaction flowslide. The failure released approximately 43 million cubic metres of iron ore tailings into the environment, polluting over 600 km of watercourses (Fonseca do Carmo et al., 2017) and resulting in 19 deaths. The event was considered to be Brazil’s worst environmental disaster, and has to date cost the mine’s owners billions of dollars (Ridley and Lewis, 2019).

The Fundão Tailings Dam Review Panel (the Panel) was assembled following the collapse to investigate and determine why the Fundão Tailings Dam (the Dam) failed in a liquefaction flowslide. The Panel reported on its findings (Morgenstern et al., 2016) on the 25th of August 2016, concluding that conditions necessary for liquefaction to occur within the Dam were present prior to failure (i.e., loose, saturated sand tailings were present), and that lateral extrusion of slimes-rich deposits underneath sand tailings provided the mechanism to trigger the liquefaction flowslide.

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