Underground Tunnel Suggested As Solution To Bangkok's Flood Problems

[anterian]

As I said cohesive forces and gravity are the prime causes of the action. As to leaks, the outlet must be at the lowest pressure.

The gravitational gradient is virtually the entire driving force, despite the popular articles you quoted. As you noted siphoning wine a small bubble which completely separates the column and therefore all possible cohesive forces will not stop the siphon.

The lowest pressure in a siphon occurs at the highest point, not at the outlet.

I think we are in agreement that gravity is the main driving force and that atmospheric pressure is the once off initiator. Without an air gap cohesive forces do play a role, an extrteme case being the self syphoning long chain polymers. With an air gap there seems to be a critical size above which syphoning ceases. I suspect that adhesive forces between the fluid and the pipe material may be an explanation. I guess it would be easy enough to do an experiment with different fluids and pipe materials. Also pipe bore will be a factor, even with fairly large diameter pipes there is some capillary action, itself the result of adhesive forces.

[whybother]

Syphoning is irrelevant in this case.

As long as the incoming end is higher than the outgoing end, water will flow.

[animatic]

Syphoning is irrelevant in this case.

As long as the incoming end is higher than the outgoing end, water will flow.

Yes, the problem is not making it go, but controlling it's path.

FROC

Forcing Rivers Off Course.

If only they knew how to intentionally do it safely,

or at least pay for it to be done properly.

Edited December 5, 2011 by animatic

[JRinger]

So the evaluation and recommendations by engineers from the Netherlands fell upon deaf ears. It was only two weeks ago that a plan was given. I guess the acedemics at Chulakorn know better.

I'm surprised one of the "experts" hasn't suggested 'lowering the sea level'

who was it that said global warming and the rise in sea level would have little or no effect on Thailand because it's too far away from the polar icecaps ?

Edited December 5, 2011 by JRinger

[septeen]

This 10 km typo has wasted a lot of time! Everyone putting in their tuppence worth. In my opinion, two logical questions to ask: (1) even if it was possible to have a tunnel 10 km deep,- what advantage would that bring over a tunnel of 500 metres deep (or less) ?

(2) The question that would have prevented all this futile discussion;- why didn't the originator of this thread check his/her facts to get accuracy first before placing it on this forum? (or perhaps the motive here is just to fill up the empty hours of all the farangs who have nothing better to do except argue online.)

[IsaanUSA]

#1) Volume

#2) And hilarity ensued!

[monkfish]

Well glad to here a few member's do realise it is possible to make water go up hill.

The example of a syphon is an extreme example but in irrigation terms a 10m difference in height could be sufficient to pump water into the sea. Anything above that probably a bonus!! Don't fob it off if you want to live in BKK cos I think you really doo need a serious solution for the future and BKK is just too build up now to start building extra rivers and canals and shit.

Do apologise for calling anyone uneducated but it really gets on my tit when people call Thais stupid when they themselves have got no frigging idea!

If you wants you can take my spelling mistakes, frame them and stick them on the wall (the rest you know about)

P.s. that's a quote from another user but it's cool.

Edited December 5, 2011 by monkfish

[monkfish]

Here is a nice tunnel build through Rock

http://en.wikipedia....ard_Base_Tunnel

While it's true TBM's Tunnel Boring Machines work well in rock, the soil under Bangkok is mostly compacted silt. And I expect waterlogged silt.

A TBM would have difficulty unless grout was pumped in front and allow to set.

A two deck tunnel (upper one for traffic when not needed for flood control) would be under the water line (BKK is about 6 m above sea level) assuming the tunnel is ~100 m below the surface. So sealing it when not needed for flood control would be problematic, and it would have to be pumped out to reuse it, plus cleaning of all the silt left from the river water.

Personally, I wouldn't drive in it.

Agreed! I am absolutely no irrigation expert but could imagine a lot of problems digging a tunnel under BKK especially ground water.

I know that was a major issue whilst building the London Underground which I guess you have also never used too? but's that OK I think it works just fine now.

Bottom line:

If Swiss engineered such a system should BKK go for it? Or would a Dutch Megga Dyke system be the solution for BKK?

One other problem I can see is Switzerland probably now has some boring equipment available to rent but they would not be able to choose the bore of the drill!

Being second hand equipment it's a fixed size.

Edit: to add link

http://en.wikipedia.org/wiki/File:TBM_S-210_Alptransit_Faido_East.jpg

Edited December 5, 2011 by monkfish

[tw25rw]

I think 10km is a misprint for 10m. It would need to have a series of rather heavy duty pumps to push that much water around. And would also need some place where it was open to the surface to allow for the water to back up if there was a blockage. 2 years seems optimistic as well.

[MengWan]

"and a depth of ten kilometers"

Is that a misprint or is it actually realistic?

They forgot to mention the pumps to dry-up the Gulf of Thaïland and siphon the water to the Pacific Ocean ...

In French, we talk of these kind of projects "pompes à fric" (money-pumps)