On 06/08/2019 11:58, charles wrote:
In article
,
Tim+ wrote:
charles wrote:
In article
, Tim+
wrote:
charles wrote:
In article , The Natural Philosopher
wrote:
On 05/08/2019 22:38, NY wrote:
"The Natural Philosopher" wrote in message
...
On 05/08/2019 12:30, Cynic wrote:
Hopefully "lessons will be learned" and dam designs include means
of drainage for maintenance or emergency. A bloody big tap at the
bottom?
No lessons will be learnt. Virtue signalling is more important than
actually achieving reliable infrastructure.
Hopefully the company that did the annual safety inspection and
pronounced the dam "absolutely fine" is well insured - because all
the work over the past week will have cost a lot.
It probably WAS absolutely fine until the heavy rain
Doubt it. From the photos of the concrete break up, the earth
underneath had been washed away for weeks beforehand.
I dont see how you can possibly infer that. Its *possible* but given
the speed with which fast moving water can erode riverbanks etc, it
seems equally likely that this was an acute event.
If the water had been going over the slipway, then I'd agree with your
suggestion. But it wasn't.
It had been going over the spillway though.
https://www.bbc.co.uk/news/uk-englan...shire-49189955
It only needed the grouting to fail between the slabs for erosion of the
soil beneath to begin.
But, seeing how many sacks were delivered, the erosion under the slabs was
massive.
--
Once the slabs lifted there would be massive erosion very quickly.
That's why you have spillways: if the water overtops anywhere else the
earth embankments fail v v quickly.
From the link I posted earlier:
'Chris Binnie, Visiting Professor, University of Exeter, Water Engineer
specialising in dams and water resources development and Fellow of the
Academy of Engineering, said:
"What would appear to have happened is that the dam was originally built
with a small spillway on the hillside beside the dam. The design
standards for spillways then increased, i.e. it became a requirement for
the dam to be able to pass a larger flood flow. To provide that, a large
central spillway was constructed on the dam surface using slabs laid on
the downstream face of the earth embankment. This has the risk that, if
the slabs crack, then high velocity water can get underneath the slabs
and erode the underlying earthfill and the slabs then settle, and
failure of the slabs takes place. This is what appears to have happened
here."'
--
Robin
reply-to address is (intended to be) valid