Stunning picture showing a portion of the huge amount of water behind, at 300 ft higher: http://www.globalconstructionreview.com/client_media/images/...
Wow, amazing to see that much water and no greenery surrounding it.
A bigger problem than ISIS: The Mosul Dam is failing
151–160 of 179 posts
Re: A bigger problem than ISIS: The Mosul Dam is failing
#152Earlier quoted context omitted.
I've seen those, but always assumed they were driving steel beams into the earth. I'm surprised that concrete can be manhandled that way without being smashed into pieces.
Driving concrete piling has generally been abandoned in USA/Canada/Western Europe due to the propensity of concrete to crack in tension during pile driving operations. Driven pile is typically steel now in most construction you will see unless you live in a place where concrete is extremely cheap compared to steel.
The steel pile-driving process is also extremely loud and creates a lot of vibration, so it's all but extinct inside urban areas.
All the projects I've seen here in recent years, and there are hundreds, use caisson holes, wide, bored holes going straight down, to create the basis of the foundation. Once drilled, they insert steel and fill it with concrete. The equipment resembles a very large-scale post-hole digger.
It seems to be fairly quick and work quite well: http://www.rwhengineering.ca/?page_id=2518
Although the drilling machines are somewhat loud, they're an order of magnitude quieter than the pile driving machines. The amount of banging those machines would generate was absolutely nuts.
Re: A bigger problem than ISIS: The Mosul Dam is failing
#153Earlier quoted context omitted.
Start with Consider Phlebas . It's the easiest to start with, but also not completely representative of what the series ends up being. I highly recommend Banks.
Most definitely. I recommend reading them in the order that they were published, which starts with Consider Phlebas. I also put Player of Games in the top 10 best Sci-fi books I've ever read I just enjoyed the ending of it so much. Banks is an incredible author. https://www.goodreads.com/series/49118-culture
was =(
Re: A bigger problem than ISIS: The Mosul Dam is failing
#154I'm curious to what ratio an abusive regime is affected by general sanctions vs the populace under its authoritarian control. Sad to see so many people living in poverty from a dictator, then sanctions, then an invasion, now ISIS (And a dam apparently). I don't know what the solution is, but that area of the world just cannot find peace.
> I'm curious to what ratio an abusive regime is affected by general sanctions vs the populace under its authoritarian control. Inevitably the sanctions will hurt the general populace more than the people in power. However, that might reduce the popularity of the leader and ultimately help their downfall, perhaps.
Or it might not. It might make the populace more isolated, bitter and paranoid, more likely to stand by the leader against the perceived evil of the rest of the world. Decades of sanctions against Cuba and North Korea just entrenched the respective regimes more tightly.
Re: A bigger problem than ISIS: The Mosul Dam is failing
#155Earlier quoted context omitted.
What happens if Jabouri gets hit by a bus? I love a good craftsman as much as anyone, but when the lives of that many people rely on one person, you're just asking for a disaster.
I'm assuming you'd deal with bus factor as everyone else who has ever relied on human labor has done -- training, more than 1 person who knows how to do a given job, etc. The world's still buzzing even though we've lived through thousands of years of people dying, I think we've had enough time to figure this one out.
> human labor has done -- training, more than 1 person who knows how to do a given job, etc
Except we're not talking about standard human labor. The guy isn't building bricks, he's maintaining a damn through "feel". That's not something that can just be easily trained.
By your logic, explain why we can't buy a new Stradivarius today. Obviously we dealt with the problem of just training someone else to do the same job throughout history by your own admission. It surely isn't lack of demand so I must not be looking in the right places. Where can I buy one?
Re: A bigger problem than ISIS: The Mosul Dam is failing
#156Earlier quoted context omitted.
I'm assuming you'd deal with bus factor as everyone else who has ever relied on human labor has done -- training, more than 1 person who knows how to do a given job, etc. The world's still buzzing even though we've lived through thousands of years of people dying, I think we've had enough time to figure this one out.
It's not like the problem of training disappears with machine learning. What if the person maintaining the ML algorithm is hit by a bus? What if the algorithm needs adapting? etc.
Then someone else picks up the code and continues maintaining it. You can read through documentation and existing code. You can't extract information from a dead guys brain...
Re: A bigger problem than ISIS: The Mosul Dam is failing
#157I rarely like The New Yorker writings, but this is actually a good one. Importantly, because it starts with short description of a whole, and then goes into the detail. Most The New Yorker writers consider it ok to start (and continue) the article with something like: "On a warm sunny autumn day he was sitting in the park, wearing his grey merino-wool polo shirt and khaki pants".
The only thing I'd like to be explained more thoroughly: what actually is this dam? I.e., how does it work? Going to wikipedia I see a whole list of different types of dams, and it is not clear to me, what does this specific construction in the article actually do, and how its failure would cause a tsunami-like wave.
Re: A bigger problem than ISIS: The Mosul Dam is failing
#158Earlier quoted context omitted.
The turbines are Francis type which means they keep spinning until the water flow is stopped. When a generator is disconnected from the power system without first removing the power from the shaft then power in is greater than power out and the result is an acceleration of the generator. Generators are built to be able to withstand a certain maximum rotational speed without flying apart for a certain duration of time…
Thank you very much for the expert information. but that still doesn't make sense to me. The article states they have two control gates and a spillway. (one gate previously defunct but now repaired) So, shouldn't it be possible to block off the turbines and open the control gates instead, so that the total flow stays (roughly) the same? Moreover, if the dam is indeed that easy to destabilize, letting ISIS control the…
I haven't re-read the article, but I recall the control gates were at the bottom of the dam. Traditionally the spillway is at the top of the dam and on one portiona there are gates which are operated hydraulically or by winches that open to allow water to pass underneath and run down a specially shaped (ogee shape) face of the dam. If for some reason the water level behind the dam gets too high there can be a section of spillway with no gates that will allow water to flow around the dam without the dam being overtopped in an uncontrolled fashion.
The mosul dam is 113 m high and the article said they were operating the dam with the water level 30m below the normal full level. Probably the sill of the spillway is only 10 or less below the normal operating level, because if the dam isn't full why would you want to spill.
The control gates at the bottom of the dam could have been primarily for allowing sediment to be sluice out from behind the dam or to allow the reservoir to be drained.
There is no guarantee the two control gates could pass as much flow as the turbines. Who knows how they were sized.
As I tried to explain before, cutting the power lines shouldn't damage any equipment. It effectively happens all the time due to natural causes, be they tree branches falling on power lines, birds, squirrels, etc.
Flow through an orifice (sluice gate, control gate, turbine, etc) varies with the square root of the pressure of water (the head), so a side effect of operating the dam with 30 m less head (30% less!) is that the turbines would be operating outside of their normal range and the control gates would pass less flow than they would at the nominal head.
There was a terrible accident at a dam in russia that was caused by operating the turbine outside of the normal range of pressure, and poor maintenance (loose bolts holding the turbine down...):
https://en.wikipedia.org/wiki/2009_Sayano%E2%80%93Shushenska...
Re: A bigger problem than ISIS: The Mosul Dam is failing
#159The Masonry dam in Washington state near Seattle also has/had this problem. The geotechnical reports and conditions were ignored and the water flowed under and around the dam, popping up in all kinds of places. The dam was never able to be filled and is just called the masonry dam since nobody wanted it named after them. https://en.m.wikipedia.org/wiki/Cedar_River_(Washington)
Masonry dam had quite a different problem which is just that there was too much water and it couldn't keep up, so water spilled over the side about 6000ft away from the dam. The problem with the Mosul dam is that it's built on soluble rock that could be swept away with enough pressure. Yes, too much water is the cause of both failures, but they're quite different.
do you have a better link to information on Masonry dam? My information is second hand from a hydro electric turbine expert. He clearly stated to me that the dam was built in a location that was geotechnically unsuitable so water flooded underground channels due to the pressure of the water behind the dam and popped up all over the place. A nearby lake level raised a bunch. I might have got the wrong link. "masonry dam" is hard to google, as intended.
Re: A bigger problem than ISIS: The Mosul Dam is failing
#160Sadly there is also a dam in Africa, in similar dire position, due to being built on a geologically unsuitable site.
[1] http://www.newyorker.com/tech/elements/one-of-africas-bigges...