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redsky's
07-28-2011, 12:21 PM
What would it take to have the Hoover Dam fail. Taking in to consideration any possible method of failure to include how to manualy remove the dam. What would happen down stream of this dam failure. What would be the economic impacts and would the dam be rebuilt?

Una Persson
07-28-2011, 12:33 PM
From the Straight Dope (https://academicpursuits.us/columns/read/2666/how-long-are-dams-like-hoover-dam-engineered-to-last)
According to all published sources I could find and the engineers I spoke to, megastructures such as the Hoover Dam are designed to last indefinitely provided they're properly maintained. The chief construction supervisor of the giant Three Gorges Dam on the Yangtze River in central China--though not yet operational, its recently completed main wall is five times the size of the Hoover's--reportedly said in 1999 that it was "difficult to predict" how long the structure might last, but his team was "endeavouring to assure" that it would hold forever.
This doesn't answer the OP directly, but is supporting information.

tomndebb
07-28-2011, 12:33 PM
While it involves some hypotheticals or conjectures, it is still more of a General Question than a Great Debate, so I am moving this thread to GQ.

Der Trihs
07-28-2011, 12:36 PM
What would happen down stream of this dam failure. What would be the economic impacts and would the dam be rebuilt?I ran across a two page article (http://science.howstuffworks.com/engineering/structural/hoover-dam-broke.htm) describing some of the aftereffects of the dam being destroyed a while back.

redsky's
07-28-2011, 12:57 PM
How would you make the dam fail

jharvey963
07-28-2011, 01:01 PM
For a fictionalized version that seems pretty valid anyway, try the novel Wet Desert (http://amazon.com/Wet-Desert-Novel-Gary-Hansen/dp/097935210X/ref=sr_1_1?ie=UTF8&qid=1311875932&sr=8-1) by Gary Hansen, who works (or worked?) at the Bureau of Reclamation. The fictionalized part is the story of someone trying to destroy it. What happens to the Dams and what can be done to save it, what will destroy it, etc. all seem realistic to my non-hydro-engineer mind.

J.

dolphinboy
07-28-2011, 01:02 PM
It's just a huge concrete structure. That being said, you could certainly set charges inside the Dam that would weaken it to a point where it began to fail, at least in certain areas. Whether this would lead to a complete collapse would depend on how many charges you used, how big they were, and where they were placed.

If the US military had an urgent need to destroy the entire dam I'm sure they would have the munitions and know-how to do it...

Machine Elf
07-28-2011, 01:19 PM
What would it take to have the Hoover Dam fail. Taking in to consideration any possible method of failure to include how to manualy remove the dam. What would happen down stream of this dam failure. What would be the economic impacts and would the dam be rebuilt?

How to destroy a dam? Aerial bombardment with bunker busters (http://en.wikipedia.org/wiki/Bunker_buster) ought to be able to get it to the point where the water rips through eventually. If you have unrestricted access to the dam, there are any number of passages and tunnels throughought the structure that can be packed with arbitrarily large quantities of high explosive.

In WWII, some German dams were destroyed (http://en.wikipedia.org/wiki/Operation_Chastise) by allied forces using bouncing bombs (http://en.wikipedia.org/wiki/Bouncing_bomb) that exploded underwater upstream of the dam for a particularly destructive effect.

What would happen downstream? History offers all kinds of lessons. (http://en.wikipedia.org/wiki/Dam_failure#List_of_major_dam_failures)

Would it be rebuilt? Depends who you talk to, but the region has grown dependent on the electricity, flood control, and irrigation water provided by the dam. I would expect it to be rebuilt.

chacoguy
07-28-2011, 02:14 PM
How would you make the dam fail

Like this. (http://glencanyon.org/publications/hiddenpassage/hp2stev.php)

enipla
07-28-2011, 02:26 PM
Although unlikely for the area, a big earth quake should do it, don't ya think?

janeslogin
07-28-2011, 06:03 PM
They are removing a dam on the Klamath River in Oregon. Press releases say it is the largest such project ever attempted. The press releases don't say how they are doing it. They say it will cost a half billion. Even the National Geographic series on the Klamath River does not say how the removal will be effected but all indications are it will be done.

BTW, I think it is a very interesting question. I have stood on the bridge at Lake Powell and wondered what would happen to the Hoover Dam if the dam at Lake Powell were to go into a catastrophic failure.

GreasyJack
07-28-2011, 06:21 PM
BTW, I think it is a very interesting question. I have stood on the bridge at Lake Powell and wondered what would happen to the Hoover Dam if the dam at Lake Powell were to go into a catastrophic failure.

I think these days it wouldn't be much of an issue because the water level in both of those reservoirs have been chronically low for the last decade. Lake Mead is only slightly larger than Lake Powell, but both are usually well below 50% capacity so at most times Lake Mead could absorb the entire volume of Lake Powell with no problems. Folks from Vegas could use those boat launches that have been hopelessly high and dry for years!

jasg
07-28-2011, 07:32 PM
A related column (https://academicpursuits.us/columns/read/2666/how-long-are-dams-like-hoover-dam-engineered-to-last) from Cecil...

Spectre of Pithecanthropus
07-28-2011, 08:02 PM
I took a tour of the dam around 1993. In those days they took you deep inside along some of the service corridors within the structure; it seemed a bit strange at one point to pass by an office of some kind with a waiting area outside, and a typical government issue bland couch for people to sit on while they waited--and all this far below the lake's surface level and so subject to millions of tons of pressure.

The guide told us that the concrete in the dam was still curing and would do so for about 1500 years. Then it would somehow "uncure" for about 1500 more years, at which point it would be susceptible to failure. Does that sound plausible to any of the engineers or builders around here?

Machine Elf
07-29-2011, 06:57 AM
I took a tour of the dam around 1993. In those days they took you deep inside along some of the service corridors within the structure; it seemed a bit strange at one point to pass by an office of some kind with a waiting area outside, and a typical government issue bland couch for people to sit on while they waited--and all this far below the lake's surface level and so subject to millions of tons of pressure.

FWIW the pressure at the bottom of the dam (on the upstream side) is about 256 pounds per square inch (though to be fair, because there are so many square inches on the face of the dam, the total force ends up being several million tons).

The guide told us that the concrete in the dam was still curing and would do so for about 1500 years. Then it would somehow "uncure" for about 1500 more years, at which point it would be susceptible to failure. Does that sound plausible to any of the engineers or builders around here?

The curing is an exponential decay process. (http://en.wikipedia.org/wiki/Exponential_decay) The less uncured material there is, the slower the curing. Wikipedia claims that core testing has shown that the concrete has continued to gain strength over the 60 years since its construction.

Previous thread here on this subject. (http://boards.academicpursuits.us/sdmb/showthread.php?t=258217)

friedo
07-29-2011, 08:21 AM
Core testing? They actually drill holes in the dam to test the concrete?

UncleRojelio
07-29-2011, 08:59 AM
I was going to give my standard answer on how to destroy any dam (if you aren't in a particular hurry) -- close the pinstocks and flood gates and walk away. Overtopping will eventually scour away the toe of the dam and it will then fail and be carried away. However the above linked article specifically mentions that the deign of the Hoover dam takes this into account.

Hoover is so over-designed that it could withstand a prolonged and extreme overtopping.

Whoda thunk it?

Dewey Finn
07-29-2011, 09:06 AM
How would you make the dam fail
Is anyone else wondering why he's asking?

WOOKINPANUB
07-29-2011, 09:26 AM
Is anyone else wondering why he's asking?

And his name is Redsky. Cooincidence? I think not...

janeslogin
07-30-2011, 02:42 PM
A story today on how a much smaller dam, 200 feet, is to be destroyed in Washington: Dams to Be Removed in Washington to Replenish Salmon - NYTimes.com (http://nytimes.com/2011/07/30/us/30dam.html?pagewanted=2&_r=1&ref=us) “Our Plan A is to use hydraulic hammers,” said Brian Krohmer, the project manager for the contractor overseeing the removal, Barnard Construction. “Plan B is explosives.”

Bryan Ekers
07-30-2011, 11:05 PM
“Plan B is explosives.”


Wuss.

astro
07-31-2011, 02:45 AM
Wouldn't a mid sized nuke ( 3-10 megatons) take out about any dam in existence?

Bijou Drains
07-31-2011, 06:05 AM
They had to put a bunch of pipes with cool water all through the dam to get rid of all the heat from the curing.

Surprised nobody mentioned the movie Force 10 from Navarone, a world war 2 movie where US commandos blow up a dam from within using a pretty small amount of explosives. Never thought that was realistic.

kanicbird
07-31-2011, 07:38 AM
Earthquake fault line movement could do it (is there one there?). It could even be upstream to divert much more water into the river to overwhelm the dam continuously, or dry it out to the point that it worthless. Yes the structure would still be there, but it would now be the Hoover Wall instead.

Perhaps a change in water chemistry cold start weakening the concrete, or some new organism that will dissolve concrete. or a significant meteor strike.


I was going to give my standard answer on how to destroy any dam (if you aren't in a particular hurry) -- close the pinstocks and flood gates and walk away. Overtopping will eventually scour away the toe of the dam and it will then fail and be carried away. However the above linked article specifically mentions that the deign of the Hoover dam takes this into account.



Whoda thunk it?

The Hoover dam is a arch pressing against the canyon sides, so not so dependent on the footing.

Morgenstern
07-31-2011, 08:59 AM
I toured the dam several years ago. Several things impressed me.

1. It's tall, really tall.
2. It's thick at the bottom, really thick.
3. It leaks inside. They have channels to handle the leakage.

The Colorado river runs through California's Imperial Valley linking the dam to the Sea of Cortez.
Much of Imperial Valley it is below sea level. The last time there was a flood in that area, the Salton Sea was created. (interesting tidbit - there's a train at the bottom of the Salton Sea.) If the dam failed, I'd expect the river to rise, the Salton Sea to become the 8th great sea, and Imperial county to offer lots and lots of new ocean front acreage.

Hail Ants
07-31-2011, 01:51 PM
You have to think of it this way: The Hoover Dam is not a wall of concrete. It is a mountain of concrete! It is as thick at the bottom as it is tall. If you had unfettered access to it and a team of engineers you could probably cause it to fail, but it will still take many, many strategically placed high explosive charges. Many of them would have to be inserted into holes bored deep into the structure itself.

If you're thinking brute force terrorist attack, forget it. Not possible, short of detonating a 1 to 3 KT tactical nuke on it. You could fly a hundred airliners into it (ŕ la 9/11) and it would barely scratch it. Be like trying to destroy Gibraltar by shooting empty beer cans at it.

Folacin
07-31-2011, 02:08 PM
The Hoover dam is a arch pressing against the canyon sides, so not so dependent on the footing.

In the Glen Canyon article referenced above (post #9, I think) - they were worried about a tunnel forming under the dam. That would basically form a fire hose, and erode away the dirt and rock at the base.

The dam itself might not collapse - but the water would drain away at an increasing rate as the hole enlarged.

kanicbird
07-31-2011, 02:22 PM
You have to think of it this way: The Hoover Dam is not a wall of concrete. It is a mountain of concrete

It's in between the 2, it is not a gravity dam, meaning it is not held in place by only by it's own weight as a mountain is, and is dependent on it's arch structure which acts as a wall.

Snarky_Kong
07-31-2011, 03:27 PM
When it was built, they didn't have the sorts of analytic tools they have now, so they used a higher factor of safety in designs. As others have noted, it's super over built.

What time frame do you want it destroyed in? Lots and lots of explosive is probably what you'd want.

AskNott
07-31-2011, 05:25 PM
The documentaries on building Hoover Dam seem to replay somewhere on TV every 2 weeks, so some of us know more about it than we really want to know. During the construction, an alternative path for the river was built, and later destroyed. Wouldn't it be simpler to reopen the bypass than to destroy the dam?

Dewey Finn
07-31-2011, 06:07 PM
The OP hasn't returned. My guess is that the Department of Homeland Security picked him up and he's on his way to Guantanamo Bay.

JBDivmstr
07-31-2011, 07:13 PM
The documentaries on building Hoover Dam seem to replay somewhere on TV every 2 weeks, so some of us know more about it than we really want to know. During the construction, an alternative path for the river was built, and later destroyed. Wouldn't it be simpler to reopen the bypass than to destroy the dam?

According to Wikipedia and a book about the construction of the dam, (that I bought while I was there) the bypass tunnels that were used during the construction phase weren't destroyed per se, the tunnels were sealed at the upstream end and again about half way thru with massive concrete plugs. The remaining halves of the tunnels are part of the existing spillway diversion system.

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