Bolts and bolting· Page 2 · AditNow Community

simonrl
51% (Neutral)
Administration

13 years ago

I think the rock type might be an issue for some.

I'm far happier with 10mm (or 12mm) bolts in slate for example than I would be 8mm.

I've got friends who have bolted and explored some very large faces in slate (and metal) mines around here. They take their hangers with them but leave the nuts. I think this is 100% reasonable. And if I want to go explore I just need to ask and they'll tell me what I need in terms of hangers.

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

Edd
50.2% (Neutral)
Newbie

13 years ago

#22

And to throw another fun one into the game .... I have just been given the challenge of working out the best way to rebolt a traverse in Sandstone! The plan is long threaded stainless bar and resin 🙂 Unless someone else can throw some light on a better solution :flowers:

'I started reading it with full intention to read it all and then got bored and went and got beer instead!'

sinker
50.2% (Neutral)
Newbie

13 years ago

#23

"edd" wrote:
.....rebolt a traverse in Sandstone! The plan is long threaded stainless bar and resin 🙂 Unless someone else can throw some light on a better solution :flowers:

Yes stainless threaded bar is the way to go. Plenty of resin and as deep as you can get them! Might be a good idea to de-bond approx 25% (or more?) of the bar closest to the surface to get a decent amount of tension in the bar. Anchors installed like this get their strength from the fixed length being deep into the rock, and rely on the "cone" around the free length resisting the fixed end from pulling out. Depends on how they are to be used, if its a straight hang (shear force on the bar) it shouldn't really be a problem though.
I'm sure someone can advise on bar diameters and depths? :flowers:

Yma O Hyd....

JonK
50.2% (Neutral)
Newbie

13 years ago

#24

I reckon we have installed about a 1000 bolts in the last 10 years. We use 10 mm Hilti every time.

I do not recommend cheap DIY type bolts or studding. Poorly generated threads can give rise to major stress raisers. In addition there is too much poor quality material in the market today. I speak from personal experience as the Product Quality Manager for a large engineering company.

Regarding hangers, if you buy them in bulk from EXPE in France the price is less than half what you pay in the UK and I beleive it makes home manufacture not worth the effort.

I agree with Mike that 8 mm is OK for deviations but prefer one size for all and the need for only one drill bit which doesn't need to be changed mid pitch.

Stainless is good when the location is wet but too expensive for normal use and often not required in slate.

davel
50.2% (Neutral)
Newbie Topic Starter

13 years ago

#25

"simonrl" wrote:
I've got friends ...

That's good to hear. 😉 (Sorry, couldn't resist that. :flowers: )

"simonrl" wrote:
... They take their hangers with them but leave the nuts.

Er ... do you mean they leave the bolts? Most of the pitches I can think of have bolts in situ but no nuts or hangers. (Which, as Simon says, is not a problem.)

Dave

Alasdair Neill
50.2% (Neutral)
Newbie

13 years ago

#26

If you use non-standard anchors then that's fine if its a site you "control" in some way to use non-standard anchors, but otherwise really think its a bad idea. For the same reason that there is a standard for, example, electric plugs. There are plenty of sites where different groups are "pushing" who probably are not in contact with each other & probably don't even know who each other are. What do you do if you travel a long way to a site to drop a pitch you believe not to have been descended before with the equipment to put in "standard" (say 8mm spits) only to find someone has been there before and put in 10mm bolts. You don't have 10mm hangers (I personally don't possess any). Do you then still put in your 8mm spits? You probably will, but that's just spreading the problem of bolt rash.
I personally think that even if you going somewhere no one else will want to go, you should make it easy & safe for anyone else if they did follow you. That means amongst other things using the standard equipment, which definitely includes 8mm and not 10mm. Regarding the relative safety, I don't think thats an argument because so much testing has been done, much of it on a professional basis. I also don't think you can divorce mining from caving after all the techniques largely originate from caving & there are plenty of people involved in both.

Alasdair Neill
50.2% (Neutral)
Newbie

13 years ago

#27

Just a further note, spotted in the latest BCA newsletter a piece about a scheme to test fixed ropes left in caves & mines. If anyone wishes to leave a rope in situ it's probably worth checking this out, because the more information abou how such ropes fare in different conditions the better. Will try & foind a link unless someone gets there before me.

simonrl
51% (Neutral)
Administration

13 years ago

#28

"davel" wrote:

"simonrl" wrote:
I've got friends ...

That's good to hear. 😉 (Sorry, couldn't resist that. :flowers: )

Well, OK, people I've met :lol:

"davel" wrote:

"simonrl" wrote:
... They take their hangers with them but leave the nuts.

Er ... do you mean they leave the bolts? Most of the pitches I can think of have bolts in situ but no nuts or hangers.

Nope, meant they leave the bolts (obviously) and often the nuts, so all you need to take is hangers.

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

royfellows
50.2% (Neutral)
Newbie

13 years ago

#29

Aly, its been a few years since I was last underground Tamar way, I believe the last NAMHO in that area, but I seem to remember both DGC and Bedford bolted with heavy rawlbolts or similar, and this is your turf?

My avatar is a poor likeness.

Alasdair Neill
50.2% (Neutral)
Newbie

13 years ago

#30

Yes, thats because the rock there really isn't suitable for anything less (soft slate & acidic). In the long term P-hangers under the BCA scheme are proposed, but there are various hurdles to cross before that happens, in particular at the moment testing has only been done in limestone & solving the issues over supply of anchors.
Rawlbolts have been quite commonly used certainly in the south west & in some S. Wales caves, & I not it sounds totally contrary to my argument about "standardisation" but in at least 2 sizes, M8's in more solid rock but where conditions (eg salt spay) give in situ fittings a short life (these have in some places been in greenstone, particularly around St Just, which is nororiously hard to drill) & larger ones in soft rock. This is not really ideal but perhaps the only longer term solution apart from p-hangers or similar.
As you know a lot of what I have done has been in various N Wales mines, certainly when I first was pushing stuff there 20 years or so ago spits were the only anchors used, in some situations not ideal but I think my argument is about size of anchor not particular typer.

Alasdair Neill
50.2% (Neutral)
Newbie

13 years ago

#31

Just to clarify my views on this,
Where rock is sound I really feel past accepted practice is followed I think there is absolutely no reason for anyone to go away from accepted practice, ie 8mm (& I fully agree that stainless studs are better in many instances than spits).

Where the rock is not suitable for these, as in general this doesn't apply in caves there is no real "standard" practice but for any well used sites p-hangers (preferably under the BCA scheme) are the best option.

If people are still going down these holes in 100 years time, perhaps p-hangers put in now would still be perfectly usable, but I doubt if anything else would.

Some years ago DCUC produced a sort of rigging guide covering all known bolted sites in Devon & Cornwall (primarliy West Penwith & Tamar Valley areas). This is probably way out of date, but perhaps something similar in other areas might be useful.
The intention was just to make sure there was a record of what was done, & to make sure if you were going to a site you knew what was needed.
If this was widely available it might attract those people who just seem to want to do SRT trips as some sort of thrill trip, which I think is highly undesirable; it would be interesting to hear anyone else's thoughts on the subject.

Morlock
50.2% (Neutral)
Newbie

13 years ago

#32

"Alasdair Neill" wrote:
If this was widely available it might attract those people who just seem to want to do SRT trips as some sort of thrill trip, which I think is highly undesirable; it would be interesting to hear anyone else's thoughts on the subject.

My personal thoughts are SRT should only be used for access or rescue.

Sure there will be diverse and differing views. 😉

Tamarmole
50.2% (Neutral)
Newbie

13 years ago

#33

"Alasdair Neill" wrote:
If people are still going down these holes in 100 years time, perhaps p-hangers put in now would still be perfectly usable, but I doubt if anything else would.

.

Not convinced that in situ anchors are appropriate in the Tamar Valley. Given the acid nature of Tamar Valley mine water in situ hangers will be subject to ongoing acid attack.

Tamarmole
50.2% (Neutral)
Newbie

13 years ago

#34

"royfellows" wrote:
Aly, its been a few years since I was last underground Tamar way, I believe the last NAMHO in that area, but I seem to remember both DGC and Bedford bolted with heavy rawlbolts or similar, and this is your turf?

At NAMHO 2007 in the Tamar Valley we standardised on 10mm Rawlbolts and Petzl hangers.

Alasdair Neill
50.2% (Neutral)
Newbie

13 years ago

#35

Quote:

My personal thoughts are SRT should only be used for access or rescue.

Sure there will be diverse and differing views.

I totally agree, but there are those who dont. In the USA there is evidently a whole section of the caving community who seem to be only interested in the SRT, if there's a cave going off at the bottom that's a no go area.

Re anchors in the Tamar Valley, the P-hangers are stainless so should survive, also need to ascertain if the acid has any effect on the resin or the resin bond. It might be worthwhile testing the pH of any water in existing rawlbolt holes at various sites. At Bedford United we have always avoided leaving anything in situ as a possible deterrant to the mineral thiefs, but it obviously hasn't worked, & we've just ended with bits being put in by others with an unknown history.

royfellows
50.2% (Neutral)
Newbie

13 years ago

#36

Many years ago I was around the Tamar and happened on a group of 3 going underground at Bedford United/Wheal Marquis.
I introduced myself to the 'leader' who was from PCG and asked if I could tag along, a request to which he readily agreed.

I was fascinated by the features of the mine and spent time photgraphing in the region of the engine shaft.
All this time the other two were chip, chip, chip.

Time to go, and all the other two had done was chip.
"Dont you want to see the engine shaft" I asked.
"Its only around the corner"

The other two glanced at each other , "Yes, OK we'll take a look"

They walked around to where you could see the shaft, "Oh yes, very good"
And that was that.

I can see the importance of gates in order to keep out the wrong kind of visitor.
:lol:

My avatar is a poor likeness.

stuey
50.2% (Neutral)
Newbie

13 years ago

#37

Odd. I didn't think there were many chippers in the PCG.

Were they from around there, or down here?

They don't sound like the usual PCG lot to me.....are you sure?

royfellows
50.2% (Neutral)
Newbie

13 years ago

#38

"stuey" wrote:
Odd. I didn't think there were many chippers in the PCG.

Were they from around there, or down here?

They don't sound like the usual PCG lot to me.....are you sure?

No the chippers were visitors, the leader was PCG, presumably taking them into the mine by prior arrangement.

My avatar is a poor likeness.

Alasdair Neill
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Newbie

13 years ago

#39

Do you have any idea who the "leader" was?

royfellows
50.2% (Neutral)
Newbie

13 years ago

#40

Hi Aly, dont sake this seriously old friend, its just what I would call an 'observation'.
OK, so lets try out my memory. This is not from a diary,but off the top of my head.

I am not very good on names, but I remember cars, not odd as ran a motor company for years. This is going to be fun.

I was in a red Cavalier, mmm, purchased BCA Measham Easter 1992, 'Major' Bircher was the auctioneer. used it for about 18 months, put it on sale, sold the 'smoker' I was then using so took the red Cav off sale and retaxed it. I think it was the second time around when I met the MCs, so this puts the year about 1994.

I was with a regular lady friend and we had camped at Mt Pleasant at St Anns Chapel, and after clearing up drove straight down to Gunnislake.

Right, the PCG leader.
A young man and very friendly and pleasant, he had a small white Fiat that had seen better days. We had some conversation about the padlock. He lost it at one point and maybe thought I had hid it, but he shortly found it again.

The 2 MC visitors were OK but didn't have much to say(MCs?), they were driving a smart newish black VW. Thinking now really harder, I think maybe a Golf Estate.

I dont want to rub salt in but I took a bin bag in with me and bought out a lot of rubbish.

Now how is that for memory, you all knew there was something odd about me.

My avatar is a poor likeness.