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Kids trapped in a cave 25

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3DDave

Aerospace
May 23, 2013
10,685
Not a result of engineering, but one that might benefit from it.

The kids soccer team is trapped in a cave. From the graphic on the news it seems there are several pools that have sealed off the exit path. The children are supposed to be unable to swim, though I don't know that that is a special limitation. More concerning is that using scuba equipment might be too complicated for them; not only are they not familiar with it, the water they will move through is so murky that they would essentially be blind, deaf, and unable to communicate so that even guides would be unable to help them escape.

There is no immediate problem for them; they are now supplied with food and water and medical care. They have been without food for a week and will take a while to recover from that.

However, there is no known time at which the water will recede from the cave. I expect that there is insufficient pumping capacity to offset the rate at which it can be replenished. On the news they estimated weeks to months before the cave might dry enough.

Since they are in the cave, the passage was certainly large enough to get in and so there should still be enough room to get out. In particular full-sized adults have made the journey.

A thought occurs to me that it should be possible to pull corrugated tubes through each of the pools and then pump those out. If the ends are above water, there should be no replenishment beyond minor leaks for the pumps to offset. Using these the children should be able to crawl out, and will have light and audible communications to guide them.

The water is apparently only 16 feet deep at most, so the pressure can't exceed 8 psi. Anchorage will be required to keep it from shortening axially, but that should be a few hundred pounds to be useful.

I would estimate that a 24 inch diameter would be enough. I'm thinking of construction as is used for ventilating manholes, possibly with stronger wire.

If the tube obstructs the path for the adults, then they can wait the few days while the tubes are placed, the children escape, and then the tubes can be retrieved. If they are anchored against the cave roof by buoyant forces, they can be flooded again and then pulled back out.


Does this seem like a feasible way out?
 
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Long tube... they are in about 4 km... and I guess part of the journey, they may need/have climbing equipment... some areas are tight and may not be accessible wearing SCUBA equipment. Still tricky.

Dik
 
A bad situation. The monsoon season usually lasts until October.

The good news is that there is a lot of help. The boys were found by two experienced British cave divers who have done this type thing before. In addition to the Thai seals, including the two doctors who are with the boys, I think the US, Chinese, and Australian military have been involved.
 
Not having studied the details, makes me wonder if they could drill down to them somewhere.
 
Accessing them from above has been talked about, including drilling or using a natural chimney, but that seems to have gone quiet. They are 800-1000 metres underground, and the terrain is rugged mountain rainforest.
 
In the diagram from it looks like the longest stretch is 200m. It looks like the need to get 1500m to get to the main base before the final pool.

Even if the entire trip can't be made that way, limiting the amount of underwater diving would be hugely beneficial.

Balancing the difficulty of placing tubes is the knowledge that many experienced divers won't even go in cave pools and the death rate for cave divers is really high, but I think it's from getting lost. Presently the kids are safe, and maybe they can stay for 3-4 months and not risk any lives beyond dropping off food and water/filters. They say that there are a couple of places too narrow to wear the air tanks.

Aside from the obvious predicament, the kids and coach are hugely lucky. I'm pulling for it to stay that way.
 
I would suggest supplied air through long tubing. With the tight clearances this may be safer than having the boys carry scuba gear. safer too than having to remove scuba gear to navigate a tight section.


Bill
--------------------
"Why not the best?"
Jimmy Carter
 
Probably need to stage the rescue. 100ft then maybe up to a couple of hundred feet between haul-outs. Use hoses to mask regulators so one only has to follow the hose. Helmets to prevent head bashes.

I'm sure a lot of parents want to strangle the idiot coach.

Keith Cress
kcress -
 
a lanyard, and a face mask fitted with a tube might do the trick.

Dik
 
I wondered about externally supplied air; the distance from the main staging area, itself cut off by floodwater, is nearly a mile from where the team is. Even at high pressure and low flow the losses for a hose of reasonable weight and flexibility seem like they could be too high. I never did enough with pneumatics to have flow calcs - anyone else do this?

There is another diagram that looks to be drawn by someone at the site that shows that the current total submersion is only required at four locations for a distance of 30 feet each. That's not too bad and maybe is why they are going for the face-masks right away (aside from the impending monsoon season.)

There aren't many pictures of the whole cave and it doesn't seem to have been previously mapped in detail. Those showing the entrance suggest that parts of it are large enough and the passages must have seemed easily passable until the water rushed in.

Here's my concern with getting the kids scuba ready - they tried to carry a phone in and the waterproof container failed, ruining the phone. That's one phone. The reports are they are experimenting with the masks but haven't tried submersion just yet. They say they want to bring them out as a group. That seems like a humane and bad plan.

They are also worried that the cave will go from partially flooded to fully flooded, though they seem to think that where the team is now will be OK but they may not be able to send supplies; that puts a rush as the monsoon season is to start in the next week.
 
I keep thinking about the old style diving suits, might be safer than masks. Put a kid in one, with an air supply, tie them off to a diver, tow them out. Less concern about the kids' masks coming loose or getting dislodged.
 
This has been discussed on other forums.

Cave diving is risky and has claimed many lives. When you throw the fact in that the kids do not know how to swim it gets complicated. One passage is very constricting and there is no room for tanks on a person, the divers had to take the tanks off and push them ahead. Then throw in panic. A big killer among experienced cave divers.

So the rescue is very complicated. And the location is remote. More rains in the forecast so there is danger of the water rising. And the water has current and is moving.




 
That's my thought dik. An escort with the child and some divers tending the hose.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
Dave; Not a mile of hose, just enough hose to pass each submerged section. Taking them all out at once seems like a guaranteed disaster.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
Here is a more stylized graphic showing the situation in the caves:

Screen_Shot_2018-07-04_at_6.15.19_AM_xozcaw.png


Perilous exit dive only way out for boys

Coming rain may force boys to swim for safety



John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without
 
And of course, there's always the unintended consequences:

Water pumped from Tham Luang flooding nearby farms


John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without
 
thinking of the "personel tube" where miners are lifted out through drilled holes, maybe a "cacoon" to fully enclose,
 
There are full-face snorkeling masks now readily available, i.e., Costco, and definitely available from manufacturers in China. The full-face masks makes it so easy, even for noobs like me. If the snorkel tubes are connected to an air supply, it might work, but 400 meters is a LONG way underwater.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
Interesting view of the cave system. Thanks to John Baker for posting it.

I have been in a couple of caves way back in the past, but they were totally dry. Still got lost! Thanks that we had an experienced guide.

This one with the water is just downright scary. And more rain and flooding on the way!!!

Hope they make it out.
 
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