China says troops rush to plug dangerous cracks in dam (50 story Zipingpu Dam above Chengdu Plain)

Associated Press via Yahoo ^ | 5/14/08 | AUDRA ANG

[Nexus]

HANWANG, China - Thousands of Chinese soldiers rushed on Wednesday to repair a dam badly cracked by the country's massive earthquake, while rescuers arrived for the first time in the epicenter of the disaster.

China's top economic planning body said that the quake had damaged 391 mostly small dams. It left "extremely dangerous" cracks in the Zipingpu Dam upriver from the earthquake-hit city of Dujiangyan and some 2,000 soldiers were sent to repair the damage, the official Xinhua News Agency said.

Xinhua said Dujiangyan would be "swamped" if major problems emerged at the dam.

He Biao, the director of the Aba Disaster Relief headquarters in northern Sichuan province, said there were also concerns over dams closer to the epicenter.

[grellis]

Is this the same as the "Three Gorges" dam? If not, how far are they from each other?

I'll admit up front: My knowledge of geology and plate tectonics doesn't go beyond high-school level. Having said that, when I first read about Three Gorges several years ago, my first thought was "earthquake." China is a country that is no stranger to large quakes. The weight of the waterpool created by the dam must be staggering. I have to wonder if that weight is enough to stress the plates into movement.

[happinesswithoutpeace]

See the “Reservoir induction” section of the below:

http://www.britannica.com/eb/article-60448/earthquake

[agere_contra]

How, I wonder, does a dam "trigger" an earthquake?

Its the billion tonnes of water behind the dam that causes the problem. That much weight of water is geologically significant in the local area. It can cause local faults to shift.

[happinesswithoutpeace]

http://news.bbc.co.uk/1/hi/sci/tech/1974736.stm

[grellis]

That’s what I have been wondering. I can’t figure anything besides the weight of the water.

[Vigilanteman]

Obviously, it would depend on how serious the cracks are. However, my gut feeling is that repairs would just buy a little time.

Google "Teton Dam failure" and "Idaho" for a case study on a much smaller scale.

Best bet would be to draw down the water behind the dam just as quickly as is safely possible before an assessment can even be made as to just how serious the cracks may be.

[thackney]

got any of that sticky crap goo left over?

[Polyxene]

Amen and Amen! The athletes who were planning on going to the Olympics must be having second, third and fourth thoughts about going to China now. That place is toxic — in more ways than one!

[Domandred]

While looking at Teton Dam again I stumbled on this:

The Catastrophic Dam Failures in China in August 1975 - note the plural

[agere_contra]

Wow. 62 dams in a single event. You weren’t kidding about the plural.

“Chu Jiaozi” indeed.

[okie01]

Its the billion tonnes of water behind the dam that causes the problem.

Okay, that makes sense. Thanks for your responses.

[Gamecock]

***Can someone tell me what a couple of thousand unskilled troops are going to do to a 50 story dam that is cracked?***

They give the appearance of doing something. If all you have is a hammer, all problems look like a nail.

I really don't think they can do anything to repair a 50 story dam.

[expatpat]

That is a little weird. But a billion tonnes of water is very, very heavy.....

[Abathar]

Send in a couple of battalions of Marines to the Hover dam and tell them to fix the big cracks in it, it would be about the same thing.

There will be plenty of witnesses to the event if it decides to fail completely I guess, that’s about it.

[WayneS]

“China says troops rush to plug dangerous cracks in dam...”

Won’t their bodies get blown out of the cracks as the water level continues to rise behind the dam and the pressure grows greater and greater?

[PapaBear3625]

Send in a couple of battalions of Marines to the Hover dam and tell them to fix the big cracks in it, it would be about the same thing.

Do we know that they are unskilled troops, as opposed to the Chinese equivalent of the Corps of Engineers?

[stlnative]

check out this headline...

Dam fear as China quake toll rises
http://www.stuff.co.nz/4546902a12.html

[cmdjing]

I left this comment in a parallel thread that stopped getting replies

The army units sent to “plug” the dam is likely media ignorance/incompetence. I believe that the soldiers sent were likely engineering units sent to clear spillways that may have been blocked by landslides caused by the earthquake. They are already draining out the reservoir.

[Ramius]

I’ve got a really bad feeling about this.

[BigBobber]

It depends where the cracks are and how big they are. Emergency repairs may be as simple as dumping sand bags onto the cracks.

They need to try to reduce seepage through the dam while drawing down the reservoir, which could take weeks or months.

Since this is May, the rivers flowing into the reservoir are likely near peak flows from the spring snow melt. Worst possible time for damage to the dam. Not a good situation.