The weather · AditNow Community

simonrl
51% (Neutral)
Administration Topic Starter

18 years ago

No, not a general rant on the weather, but does anybody worry about the weather and the greater likelihood of collapse whilst underground when its really wet? Weight of gronud above, lubricating effect of water etc?

my orders are to sit here and watch the world go by

Captain Scarlet
50.2% (Neutral)
Newbie

18 years ago

#2

Not in the slightest, actually I tend to spend the rainier days U/G. I have never had any effect from rain underground except one place where the water level rises from belly to chest deep after a really prolonged wet period.

STANDBY FOR ACTION!!!!...

simonrl
51% (Neutral)
Administration Topic Starter

18 years ago

#3

I used to get a bit edgy in certain slate mines when it had been really wet, I reckon that it does have an effect on the likelihood of a collapse, but I've given up worrying about it 😉

my orders are to sit here and watch the world go by

Wyn
50.2% (Neutral)
Newbie

18 years ago

#4

You're right about water 'lubricating' made up ground. I've seen examples of poorly compacted tips (not mine or quarry) open up tension cracks, into which water flows creating a shear plane and hey presto tons of earth/fill are suddenly travelling down hill. Hopefully this won't happen to a spoil heap above an adit.

Mind you the weight of water can be benificial in stability. Many years ago my brother was working on lowering the level of Llyn Peris for the Dinorwig hydro scheme. He was moored in a boat offshore, when there was a rumble and a volvo earth tipper was up to it's axles (and they have Big wheels) in water. Apparently the sheer weight of water had stabilised the slate spoil at lake level. I think it damaged the new lower access road and they had to do a lot of remedial work.

simonrl
51% (Neutral)
Administration Topic Starter

18 years ago

#5

IIRC the Cwmorthin adit collapse was after a period of extended and particularly lousy weather. Late October 05 I think - Barney had a more exact date.

Here's Miles peeping out of the freshly collapsed adit:

[img]http://www.aditnow.co.uk/showimage?f=/community/Cwmorthin-Slate-Mine-06-11-2005-Image-002/[/img]

my orders are to sit here and watch the world go by

Barney
50.2% (Neutral)
Newbie

18 years ago

#6

"simonrl" wrote:
IIRC the Cwmorthin adit collapse was after a period of extended and particularly lousy weather. Late October 05 I think - Barney had a more exact date.

Yeah this was discussed on DP. Iirc, oct 13th '05. The thread should still be on there.
The day it collapsed there was water gushing down the mountains like a bath overflowing, and there isnt anything more than a couple of streams normally.

How is wales at the moment?
We have Stratford town centre underwater at the moment, and surrounding villages. We have nearly lost sainsbury's too-Yay! 😮

hymac580c
50.2% (Neutral)
Newbie

18 years ago

#7

I used to get quite woried underground at Rhosydd when weather was very wet as you find water coming it in many places and you can also hear it. When you think about it 1 litre of water weighs approx 1 kg. And peat absorbs water. So say a week of heavy rain on the Moelwyns = how many tons extra weight on top of an old mine? I think best not to think about it when underground on a rainy day.

Bellach dim ond swn y gwynt yn chwibian, lle bu gynt yr engan ar cynion yn tincian.

Wyn
50.2% (Neutral)
Newbie

18 years ago

#8

Of course it doesn't help that the surface above Cwmorthin/Oakley is extensively and deeply fissured. Lots of points of ingress for surface water.

hymac580c
50.2% (Neutral)
Newbie

18 years ago

#9

Indeed, when you think about it the water running down the cracks, washing away more and more shale over the years. I suppose it does weaken the top structure especially when there is not a lot of depth in the structure. What of when there is heavy frost after rain, and the ice expands the cracks and joints out more each time? Do you think a long dry spell does damage to the mines? I would not mind a month or so of it.

Bellach dim ond swn y gwynt yn chwibian, lle bu gynt yr engan ar cynion yn tincian.

LAP
50.2% (Neutral)
Newbie

18 years ago

#10

Little or no affect in most mines, apart from those which are in some way linked to open quarries. For instance, you wouldn't expect an ardinary tunnel to be affected, but a massive chamber might be.. due to the large surface area of the roof, thereby increasing the chances that there is going to some kind of crack in the roof/walls.. allowing seeping into the chamber, which may cause some of the roof slabe to become unstably... and if this for whatever reason freezes, it can of course crack the roof... which isn't usually good.

Kein geneis kanaf - Cain gnais canaf
Byt vndyd mwyhaf - byth onddyth moyav
Lliaws a bwyllaf - Líows o boylav
Ac a bryderaf - ac o boryddarav
Kyfarchaf y veird byt - covarcav yr vairth
Pryt nam dyweid - poryth na'm dowaith
Py gynheil y byt - Pa gonail y byth
Na syrch yn eissywyt - na soroc yn eishoyth
Neur byt bei syrchei - nour byth bai sorochai

Vanoord
54.4% (Neutral)
Newbie

18 years ago

#11

"Barney" wrote:
Yeah this was discussed on DP. Iirc, oct 13th '05. The thread should still be on there.

The day it collapsed there was water gushing down the mountains like a bath overflowing, and there isnt anything more than a couple of streams normally.

I've looked, but I can't find that thread. IIRC I worked out the weight of water and came to the conclusion that it could add the equivalent of about a foot of rock, which isn't a lot when the chambers are in excess of 100' underground.

But... the lubricating effect of water is the problem, particularly in conjunction with it washing away shales etc which will lead to collapse. As Wyn says, the ground in some places is very fissured and I would expect the area above Rhosydd to look worse than usual.

Whether or not we can blame the recent collapses in Croesor on the weather, I don't know - but if more water than usual is dripping down through into the mine and washing away granules in the roof, then I suspect it's very possible. That said, it's the tips that are more likely to be affected, so I guess the real worry has to be Cwmorthin's main adit 😞

Hello again darkness, my old friend...

Wormster
50.2% (Neutral)
Newbie

18 years ago

#12

"Vanoord" wrote:
Whether or not we can blame the recent collapses in Croesor on the weather, I don't know - but if more water than usual is dripping down through into the mine and washing away granules in the roof, then I suspect it's very possible.

S'funny that this should pop up I was talking to one of my brothers about mind degradation just yesterday. I don't think that in the case of Croesor, excess water is responsible for the recent collapses.

Think about it for a moment...........ANY manmade structure that is left unmaintained for any length of time WILL start to collapse, just take a look at Rhoysdd chapel, how long ago did it loose its roof? ask yourself that question next time you walk past. Same with Cwmorthin lake level adit, unmaintained for over what 100 years, that's collapsing. Or the lower levels of Croesor mine, how long did it take them to flood once the pumps had been turned off?

Its happening all the time, and its something that we have to factor in when undertaking any trip.

Better to regret something you have done - than to regret something you have not done.

hymac580c
50.2% (Neutral)
Newbie

18 years ago

#13

The roof of Cwmorthin chapel was removed by a certain person for material to make a roof a house. The timbers on the roof were removed by someone else about 4 years ago using a rope and a tractor on the back wall so I am told.
Talking about water, I always wondered why that in slate quarries of poor quality material such as Moel Fferna and Cambrian etc that the slate material taken from the mine which are on the surface and exposed to the atmosphere have split and cracked badly.And some of it will disintigrate when crushed by hand even. And you find that areas exposed to water like addit enterances and where water runs in has a lot of shale and has split up badly.
Any theories on that?

Bellach dim ond swn y gwynt yn chwibian, lle bu gynt yr engan ar cynion yn tincian.

Manicminer
50.2% (Neutral)
Newbie

18 years ago

#14

Excesive rainfall can lead to minor earthquakes that will dislodge dodgy roofs etc. We had a number of them about 4-5 years ago.

Gold is where you find it

Wyn
50.2% (Neutral)
Newbie

18 years ago

#15

Quote:

Excesive rainfall can lead to minor earthquakes

Don't you mean earthslips?

Manicminer
50.2% (Neutral)
Newbie

18 years ago

#16

I mean actual minor earthquakes that occur a few miles away and the tremors dislodge any loose slabs.

Gold is where you find it

Wyn
50.2% (Neutral)
Newbie

18 years ago

#17

Yes, I know what you mean. I was living above Bethesda in July 1984 when a earthquake hit North Wales at 5.4 on the richter scale. Once I'd got out of house it was intersting to see slates and chimney pots coming down and the garden (dry stone) wall starting to collapse, but the thing that stayed in my memory was the racket caused by loose rubble falling from the terraces in Penrhyn.

JohnnearCfon
50.2% (Neutral)
Newbie

18 years ago

#18

It caused some falls on the terraces at Dinorwic. Making access to some places not as direct as before!

LAP
50.2% (Neutral)
Newbie

18 years ago

#19

"JohnnearCfon" wrote:
It caused some falls on the terraces at Dinorwic. Making access to some places not as direct as before!

You're right... My dad "Allan" posted a comment of such events on ME... I was one of the people with him.

Kein geneis kanaf - Cain gnais canaf
Byt vndyd mwyhaf - byth onddyth moyav
Lliaws a bwyllaf - Líows o boylav
Ac a bryderaf - ac o boryddarav
Kyfarchaf y veird byt - covarcav yr vairth
Pryt nam dyweid - poryth na'm dowaith
Py gynheil y byt - Pa gonail y byth
Na syrch yn eissywyt - na soroc yn eishoyth
Neur byt bei syrchei - nour byth bai sorochai