6 October 2010
Interesting images of the Ajkai Timfoldgyar tailings dam accident in Hungary
Posted by Dave Petley
As predicted, a number of interesting images are now available of the site of the breach that caused the Ajkai Timfoldgyar tailings debris flow in Hungary on Monday. Thanks again to Peter Diehl for his tireless work in seeking out and highlighting the best images. The best slide show, surely destined to become an invaluable teaching aid, is available at this link:
http://galeria.index.hu/belfold/2010/10/05/legifelvetelek_az_atszakadt_gatrol/
In terms of the failure that caused this dreadful event, the best images are these two below. Take a little time to appreciate the scale of this – the first image has some machines in the foreground that provide perspective. The first image shows the breach itself:
The really revealing image is this one – the breach is to the right of the image. It suggests that this block had moved off its foundation and that the section close to the reach had moved forward. Note the material that has come through the resultant crack:
The fact that the final failure occurred in a right angled bend in the dam wall is very interesting, as this is a point of stress concentration. If I were the team investigating this failure I’d be very interested to see the calculations of uplift force on the base of the dam.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
bbc has a good post on the disaster:http://www.bbc.co.uk/news/world-europe-11488386
Glad to see the photos I linked too yesterday got to the front page. "If I were the team investigating this failure I'd be very interested to see the calculations of uplift force on the base of the dam."If I were investigating this I'd be surprised if any calculations were done at all for the structure you can see in the photographs. I would not be surprised if this was originally designed as quite a low dam and heightened and steepened since as often happens at site such as these.What is also of note is the presence of sludge on the dam crest in the photo showing the crack to the right of the breach. This would indicate to me that the dam was about to overtop before it failed, and shows that there may not have been any overflow or drawdown capability to prevent overfilling as a result of excessive rainfall.As a dam engineer, I'm constantly surprised that tailings dams are subject to less scrutiny than others given their potential to cause the same loss of life compounded with the potential for environmental catastrophe.
Hi Dave, just one comment, Ajkai Timfoldgyar is not a mine. and it was not a mining accident. Rita from Ajka