Author Topic: Cave Draughts - again  (Read 2521 times)

Offline mrodoc

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Cave Draughts - again
« on: August 31, 2016, 10:28:37 am »
Some while ago somebody posted a link to a paper on this subject. I am increasingly puzzled by the draught coming from our dig. It seems to be constant and cool with the occasional waft and is sufficient to make us feel cold if not actively digging. It is always outward. We are 40 metres down in a fault zone. There are no stream sinks in the area and no other caves of any size for well over a kilometre. What on earth is driving it!

Offline Leclused

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Re: Cave Draughts - again
« Reply #1 on: August 31, 2016, 10:36:40 am »
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Offline Rob

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Re: Cave Draughts - again
« Reply #2 on: August 31, 2016, 10:48:12 am »
Some while ago somebody posted a link to a paper on this subject. I am increasingly puzzled by the draught coming from our dig. It seems to be constant and cool with the occasional waft and is sufficient to make us feel cold if not actively digging. It is always outward. We are 40 metres down in a fault zone. There are no stream sinks in the area and no other caves of any size for well over a kilometre. What on earth is driving it!
That sounds quite similar to the Bull Pit dig in Derbyshire, in that it always drafts out, although it is closer to known caves...

Does anyone have a link to Leclused's papers (or similar) in English?
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Offline mrodoc

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Re: Cave Draughts - again
« Reply #3 on: August 31, 2016, 11:46:25 am »
I suggest using Google translate!

Offline braveduck

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Re: Cave Draughts - again
« Reply #4 on: August 31, 2016, 11:50:09 am »
I believe three digs in the Dales have been dug on faults .Always strong draughts but cave never discovered ! :(

Offline Leclused

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Re: Cave Draughts - again
« Reply #5 on: August 31, 2016, 11:55:51 am »
Some while ago somebody posted a link to a paper on this subject. I am increasingly puzzled by the draught coming from our dig. It seems to be constant and cool with the occasional waft and is sufficient to make us feel cold if not actively digging. It is always outward. We are 40 metres down in a fault zone. There are no stream sinks in the area and no other caves of any size for well over a kilometre. What on earth is driving it!
That sounds quite similar to the Bull Pit dig in Derbyshire, in that it always drafts out, although it is closer to known caves...

Does anyone have a link to Leclused's papers (or similar) in English?

I've only posted the link  :) All credits go to Baudouin LISMONDE.

I don't think there is a translation of this work in English. But there are other papers about this topic

Just google : "cave climate assessment of airflow and ventilation"

and then the following paper pops up on several sites.

https://www.researchgate.net/publication/229533954_Cave_climate_Assessment_of_airflow_and_ventilation

And an other one: http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1091&context=ijs

And this ones seems not to bad either (but not very in detail)
http://www.purdueoutingclub.org/files/caving/docs/Cave_Air_Basics.pdf

« Last Edit: August 31, 2016, 12:14:50 pm by Leclused »
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Offline The Old Ruminator

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Re: Cave Draughts - again
« Reply #6 on: August 31, 2016, 06:42:54 pm »
One of the strongest draughts I have seen locally was out of a tiny cave on The Quantocks.( Aisholt Cave ). A small tube leads 3m into a boulder blocked chamber. At times the ferns outside the cave can be seen moving. Local squatters kept their milk in the tube.

Although leading into a giant chamber Topless Aven Dig in Reservoir Hole never draughted strongly though there are hard to define draught routes in the chamber itself. Certainly at times a draught pulls inwards through the boulder choke at the end of High Country. Skyfall Aven draughted well though it was always difficult to define the origin. Possible a circulatory draught exists.

Vurley has always draughted well. Always outwards and cold I believe . The terminal choke is still draughting cold and outwards. Digging has always followed the draught though this resulted in an irregular route.. Smoke testing is done on a regular basis.

The end of Shatter Cave draughts well and this is at its strongest in the crawl below Plughole Chamber. Further into that area the draughts origin is hard to ascertain.A draught reversal has been encountered here. In the parallel Withyhill Cave a strong draught exists in the dig between Jonathan's Chamber and the big boulder chamber beyond. Again the draught gets lost here though I am not entirely sure it comes from the only dig up there at Priceless Grotto. I dug there originally and can't remember one.

Importantly for diggers does a draught imply caverns beyond or are we smoke wafters chasing our tails ? I think a lot more research in this area is required particularly where digs are involved.

Offline mrodoc

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Re: Cave Draughts - again
« Reply #7 on: August 31, 2016, 06:48:43 pm »
I believe three digs in the Dales have been dug on faults .Always strong draughts but cave never discovered ! :(

That's encouraging   :unsure:

Offline Leclused

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Re: Cave Draughts - again
« Reply #8 on: August 31, 2016, 06:52:28 pm »
Just to spice up the thread a vidroclip taken at the end of the tunnel leading
towards salle Verna on the Psm

https://dl.dropboxusercontent.com/u/1068395/Movies/PSM/Salle%20Verna%20Courant%20d%27Air.wmv

In the summer the draught is enormous. This is the lowest entry of the psm system
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Offline martinb

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Re: Cave Draughts - again
« Reply #9 on: August 31, 2016, 07:18:06 pm »
Over the years, we have dug in a number of places, always (trying) to follow draughts. Currently, we have one dig where there is a very faint cold draught, which is encouraging, but as we dig, we keep loosing the draught. Then, as we get a little despondent, we move a seemingly insignificant rock, and, lo, theres the draught again.

The other dig, which has now been ongoing for nearly 5 years, originally we were digging in the lowest part of the cave following a tiny trickle of water, then again, cool draughts kept popping out from various places, some of which we followed - rather fruitlessly - until we hit the mother lode.

We are now about a further 20+m further down, having found cave in the middle, following another trickle of water. Once again, we get occaisional blasts of cold (not cool) air.

We surmise that there could be a sump somewhere that empties itself like a u-bend and sends a cold draught towards us. We know where the water ends up, and we know that there is another cave on the upstream end, so......

Offline pete h

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Re: Cave Draughts - again
« Reply #10 on: August 31, 2016, 10:28:35 pm »
I believe three digs in the Dales have been dug on faults .Always strong draughts but cave never discovered ! :(

That's encouraging   :unsure:

Spider Hole,  following a draught down through boulders in a fault, cave found.
 Charterhouse Cave chill out choke i believe was formed on a fault, again following a good outward draught,,4 km cave found.

Offline mrodoc

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Re: Cave Draughts - again
« Reply #11 on: September 01, 2016, 07:36:46 am »
Ypu have cheered me up Pete :)

Offline Rob

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Re: Cave Draughts - again
« Reply #12 on: September 01, 2016, 08:47:12 am »
That's an impressive clip from Verna, i wonder if it calms down at all after the doors have been open a while?

Makes our project in Mulu seem almost tame!
https://www.dropbox.com/s/gr0fsdqsadnpb0k/Mulu%20P1100293.mp4?dl=0
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Offline Leclused

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Re: Cave Draughts - again
« Reply #13 on: September 01, 2016, 09:53:11 am »
That's an impressive clip from Verna, i wonder if it calms down at all after the doors have been open a while?

When you can wait until winter ....

D
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Offline Dickie

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Re: Cave Draughts - again
« Reply #14 on: September 04, 2016, 10:36:27 am »
That's an impressive clip from Verna, i wonder if it calms down at all after the doors have been open a while?

Nope - they get a LOT harder to close!!
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