3 gorges dam at risk??

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vtsnowedin
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Post by vtsnowedin »

kenneal - lagger wrote:It's even more simple than that. The pressure on the dam is equal to half the square of the height of the water times the density of water and the maximum pressure is exerted at the base.
The pressure is easy to calculate being just the depth of water in feet times its weight of 62.4 pounds per cubic foot which computes to 0.433 PSI per foot of depth. The moment of over turning however and the resistance to sliding are more complicated and require the dimensions of the dam cross section and a coefficient of friction for the foundation material to compute accurately.
That dam in Austin PA, was designed to be thirty feet thick but was only built twenty feet thick so failure was preordained. The first failure killed 78 people but undaunted they rebuilt it and that version failed years later but without loss of life.
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Post by kenneal - lagger »

The more that we post about this the more that is is coming back to me after 50 years or so.

The maximum pressure is the height of water times its density and this acts at the base of the wall. The total pressure is a triangular distribution, maximum at the bottom and minimum at the top, so is the height of water times the weight times the height divided by two. This acts at one third the height of the water and is countered by the weight of the wall plus any weight of water acting downwards on the structure of the dam.

I'm not, however, going into the business of designing dams any time soon as the above is the easy bit and the rest gets more and more complicated as you move on. I'll stick to designing houses and insulation systems.
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vtsnowedin
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Post by vtsnowedin »

kenneal - lagger wrote:The more that we post about this the more that is is coming back to me after 50 years or so.

The maximum pressure is the height of water times its density and this acts at the base of the wall. The total pressure is a triangular distribution, maximum at the bottom and minimum at the top, so is the height of water times the weight times the height divided by two. This acts at one third the height of the water and is countered by the weight of the wall plus any weight of water acting downwards on the structure of the dam.

I'm not, however, going into the business of designing dams any time soon as the above is the easy bit and the rest gets more and more complicated as you move on. I'll stick to designing houses and insulation systems.
Yes to all of your post and I also will not be designing any dams. If you wanted per chance to build a good road recycling most of the material already in the road bed I know how to do a really good job of that, but as to do it right cost more then a little money I have had few takers as most can't see beyond their next budget or election cycle. :cry:
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Lord Beria3
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Post by Lord Beria3 »

https://www.taiwannews.com.tw/en/news/3951673

Came across this story today.

Sounds terrifying.
As torrential rains in China continue to wreak havoc on more than 24 provinces, notable Chinese hydrologist Wang Weiluo (王維洛) has questioned the safety of the massive Three Gorges Dam, warning that it could collapse at any moment.

In southern China, regional rainstorms and mudslides that began on June 1 have uprooted more than 7,300 houses and affected nearly eight million people as of Monday morning (June 21). The immediate economic loss is estimated at 20.6 billion RMB (US$2.9 billion) by local officials.

The nonstop downpours have also raised the Chinese public's concerns over the potential bursting of the world's biggest hydropower project. Despite government assurances that the dam is structurally sound, Wang has taken an opposing view and claimed that the facility is not as stable as many have been led to believe, reported New Talk.

Wang pointed out that the dam's design, construction, and quality inspection were all carried out by the same group of people and that the project was finished too quickly. He said that even Chinese Vice Minister of Water Resources Ye Jianchun (葉建春) confessed at a June 10 press conference that water levels of at least 148 rivers in the country have risen above warning thresholds, which proves that the Three Gorges Dam has a limited effect on flood control.

Rather than commenting on the validity of the images showing the dam's warping a year ago, Wang said a more serious concern is the cracks and substandard concrete discovered during its construction. He said a failure of the dam would have catastrophic consequences for individuals residing in the lower reaches of the Yangtze River and that they should prepare for evacuation as soon as possible, reported CT Want.
Speaking openly in China about this type of thing is very brave in Communist China.

His family could be at risk by speaking out.

So why is the chap doing it? He must have very real concerns about the structural viability of the dam.
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Lord Beria3
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Post by Lord Beria3 »

Peace always has been and always will be an intermittent flash of light in a dark history of warfare, violence, and destruction
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Post by RenewableCandy »

UndercoverElephant wrote:
emordnilap wrote:It's able to withstand a 'worst flood in 100 years'. WTF does that even mean?
I don't think I'd find it very reassuring if I lived in the area myself.
We've had a couple of those here in York in the past decade.
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