Zurich researchers find the cause of a dam burst in Brazil
Published: Tuesday, Jan 16th 2024, 15:20
Updated At: Wednesday, Jan 17th 2024, 00:59
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A Zurich-based research team has uncovered the cause of a dam failure in Brazil five years ago that killed at least 270 people. According to the study published in the journal "Communications Earth & Environment" on Tuesday, this will allow timely action to be taken in the event of impending dam failures in future.
The dam of a tailings pond at the iron ore mine in Brumadinho in south-eastern Brazil burst on 25 January 2019. The sludgy residues from the ore processing, known as tailings, stored in the pond flooded neighboring settlements and landscapes in an avalanche of around ten million cubic meters of sludge. Although the dam was monitored by a monitoring system, no one had foreseen the disaster.
Exactly why the dam collapsed was previously unclear, as the Swiss Federal Institute of Technology in Zurich (ETH Zurich) emphasized in a press release on the study. In particular, it remained unclear why the dam collapsed in 2019 of all years, three years after the sedimentation basin was last loaded with new tailings.
Physical process
The ETH researchers have now traced the delayed dam break using models. The result: the breach is linked to a physical process that took effect after the mine was shut down. Specifically, according to the study, sliding surfaces expanded, causing the deposited material to slide and damage the dam.
According to the model, the growth of the sliding surface is caused by so-called creep deformations. These are tiny, slow earth displacements in the fine-grained, brittle tailings. These were caused by the uneven pressure distribution in the overlying deposits.
According to the university, the ETH researchers' model can predict the probability of a dam bursting for existing dams. This means that measures such as the dismantling of reservoirs or the evacuation of affected settlements could be taken in good time in the future.
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