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Kids trapped in a cave 25

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3DDave

Aerospace
May 23, 2013
10,688
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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Elon Musk has decided to get involved offering some ideas as well as resources and personnel:

Elon Musk is sending engineers to Thailand to help soccer team rescue efforts


John R. Baker, P.E. (ret)
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Irvine, CA
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Further news on the conditions - a diver expressed that there is a net out-flow from the cave, so that divers have a current to fight to reach the team. As the current approaches the speed the divers can swim/pull themselves the time required rapidly approaches infinity.

This also leads to explaining the death of the Thai diver, Saman Kunan, RIP. If he was even a little slower he would be struggling more to make progress and taking longer. If the water is not clear he might not have been able to see the pressure gage or even a watch to better estimate. If he timed it to take so many hours, just a bit longer would be lethal.

Without current the duration of the trip would be easily predicted.

The good news is that it is outflow, so the time the escaping children will need to be under water is greatly reduced. The bad news is the onset of monsoon season and predictions of imminent rain mean they may have to do this without enough practice or worse, enough equipment.

They are pulling a nearly 3 mile long air line to the team, but it gets back to the ability to push enough air at the pressure the hose can take to overcome the flow losses.
 
I wonder if they could set off a smoke bomb(device) in the cave and check the the outside for any visible sign of smoke escaping which could pinpoint other exits not yet found....the downside is that it may contaminate any remaining air in the cave....no easy answers here, just pray that it all will end well...
 
SAIL3: They've pist away a valuable week... does not bode well.

Dik
 
I see two issues with Elon Musk's long nylon tube idea.
Locating a suitable tube quickly.
Installing the tube against the outflow current.
If a suitable tube can be located, the onsite divers can probably find a way to install it.
In regards to drilling an escape passage, I hope that someone checks the ambient air pressure in the cave first. If the air pressure is above atmospheric, you don't want to vent an air pocket and allow the water to completely fill the chamber.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
It appears that an active rescue effort is now underway:

Rescue Operation To Save Boys Trapped In Cave Begins

Rescuers said it would take many hours before the first boy emerged from the cave.



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
 
If they have a crew, and, can work in shifts... why stop at night; there's little difference in the cave. It's kinda dark anyway.

Dik
 
Hi dik;
"If they have a crew, and, can work in shifts... why stop at night;"
There must be a reason.
With the impending rains I am sure that the rescuers feel the pressure more intensely than we do.
I would speculate that only the divers with the most experience in this cave were used on the initial rescue.
It is quite possible that the first rescue shift divers may be paired with other divers on the second day.
I feel that there is an excellent chance that all the boys may be rescued on the second day, but time will tell.
What is needed now is not our speculations but our prayers.
And, all our speculations may become moot after the next two days.
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
Bangkok Post said:
Four more boys safely out as day two mission ends


Bill
--------------------
"Why not the best?"
Jimmy Carter
 
HotRod10 - thanks for the link. There's a lot of work going on - I bet it is very physically exhausting.

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You do know that there is a required rest period for divers between dives. Something about nitrogen in the blood.
 
They have 8 out but the remaining ones are the weakest so they may be more difficult to extract. Supposedly the coach is in worse shape than the kids because he gave them all his water and food before they were found. Hope the rains hold off.

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No more decompression is required than for passengers on commercial flights. Although, fun fact, it has occurred that divers who are just below normal decompression requirements have developed the bends when hopping on commercial flights a bit too soon; they would have been fine if they'd stayed on the ground for another day, but the drop in pressure relative to the dive pressure is too much.

That it takes so many hours to get in and out over such a short distance for people who are likely in top physical condition and desperate to accomplish this task suggests a huge physical effort is required. I expect there aren't many people running back-to-back marathons and those are only a few hours with unrestricted movement and plenty of air.

I think the rescue team has had huge luck in the lack of rain allowing the pumping to get ahead of the inflow.
 
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