Bolting

[mikem]

Sleeve / Rawl / through / expansion bolts are all pretty much the same thing.

 

[georgenorth]

Apologies that should have been ?shield? anchor rather than sleeve anchor.

Anyhow, Rawlbolts (e.g. https://www.screwfix.com/p/rawlplug-rawlbolts-m10-x-75mm-5-pack/20828) can normally be removed fairly easily. Thru-bolts are essentially un-removable.

 

[Tseralo]

+1 from me on concrete screws. Ive even bolt climbed on them with no issues. We were able to remove them all and abb back out on a natural leaving no trace. Ive no idea how many boxes members of the TSG have placed in the last few years but its a lot.

 

[Fishes]

Another option to concrete screws would be M10 shield  anchors (Rawlbolts). They go in a 16mm hole, so you could re-use the hole for resin anchors if required. I probably wouldn?t fancy leaving them in-situ in a mine for longer than a few months though due to corrosion.

I didn't realise they still made these. I remember drilling holes for them with a star drill which was a really time consuming PITA. Spits were a big step forward for general use.

They might be a sensible choice if you have very corrosive mine water somewhere but I don't think most people would go back to them. An 8mm hole takes a quarter of the time to drill and you can drill 4 times as many holes plus a lot of lightweight drills used for rigging just don't have enough grunt in them.

 

[Chocolate fireguard]

Henry Rockliff did a lot of testing of them in concrete at my training centre in Rotherham some years ago. I was genuinely amazed at how strong they were. I don't remember ever seeing any dynamic load test results. A 9kN dynamic force with an additional 300kg added to the dropped weight would generally be considered as being an appropriate substrate strength. They would only have to have a min 12kN BL to pass the EN795A standard and they are much stronger than that.

I don't understand the bit about the 9kN dynamic force with an additional 300kg added to the dropped weight.
Are you adding the weight of the 300kg to the dynamic force to get the 12kN?

 

[georgenorth]

Another option to concrete screws would be M10 shield  anchors (Rawlbolts). They go in a 16mm hole, so you could re-use the hole for resin anchors if required. I probably wouldn?t fancy leaving them in-situ in a mine for longer than a few months though due to corrosion.

I didn't realise they still made these. I remember drilling holes for them with a star drill which was a really time consuming PITA. Spits were a big step forward for general use.

They might be a sensible choice if you have very corrosive mine water somewhere but I don't think most people would go back to them. An 8mm hole takes a quarter of the time to drill and you can drill 4 times as many holes plus a lot of lightweight drills used for rigging just don't have enough grunt in them.

Yes, the bigger hole diameter is the obvious downside. A modern 18V drill will thump in a hole that size in next to no time though.
To my mind there?s pretty much no justification for using thru-bolts in any situation because they?re so difficult to remove.
Personally, I?d use concrete screws. Caving isn?t work, so fortunately there?s no requirement to do things by the safest method...

 

[Mark Wright]

Henry Rockliff did a lot of testing of them in concrete at my training centre in Rotherham some years ago. I was genuinely amazed at how strong they were. I don't remember ever seeing any dynamic load test results. A 9kN dynamic force with an additional 300kg added to the dropped weight would generally be considered as being an appropriate substrate strength. They would only have to have a min 12kN BL to pass the EN795A standard and they are much stronger than that.

I don't understand the bit about the 9kN dynamic force with an additional 300kg added to the dropped weight.
Are you adding the weight of the 300kg to the dynamic force to get the 12kN?

The 12kN test is a static test for 3 minutes in the direction of intended use.
The dynamic test consists of usually dropping a 100kg weight onto a length of dynamic rope with sewn terminations. The test weight is dropped a sufficient distance to generate 9kN. The additional 300kg is added to the dropped weight. If it holds the load then it would generally pass the test. They generally do the drop test 3 times.

Mark

 

[Chocolate fireguard]

Thank you.

 

[markpot]

Wow! As always the caving community delivers,thanks all so much for the informative replys and kind offers of help. After digesting this thread,doing some reading and some head scratching we are going down the concrete screw route with a view to replacing with chemical anchors if needed. The Op was promted by our want to the best we can from the start. Concrete screws are a new thing for me having placed many bolts in the past of varying variety. Time for some practice. @pete, if you could dm the knowledge on the preferable combos of anchors and resin for derbyshire,we would like to stay in line with that and are happy to fund out of our own pocket.Bob messaged me kindly offering use of the test puller. Once again,thanks all for the input,hopefully it goes 

 

[pwhole]

Do still get the best ones you can afford, after all that discussion - many are total crap - usually the ones you get given at work

 

[Cantclimbtom]

Have been reading the thread with interest until now. Thanks everyone.
While (to Sinker's possible disgust, thanks for posting the explanation!) I personally still would consider concrete bolts, after reading this although I'm very restrictive on when I'd think them suitable. Definite agreement that for anything longer than really really short term they are sketchy.

Just for your amusement value... for an temporary aid ladder I would favour them (6mm or 8mm) over brown rawlplugs (7mm hole) with occasional expansion bolt.

Worth repeating is that you can remove them easily (the same day?) and fill the entrance to holes with some grey resin and/or a broken bit of rock, which you could do when installing permanent anchors with whatever is left in the tube.

worth a mention and maybe winner for short term anchors are drop in anchors for *temporary* placements. Spit if you want. (pun intended). These should be removable with a ball joint separator bashed in behind a hanger (or HSS shoved down hole if really stubborn)  *as long as* they are of the wedge-first variety which are hard to get. Fischer make a kind of screw-in version of this to allow removal, but only 12mm drill hole and upwards
https://youtu.be/wCSUr3BMgM0


Fair disclosure... I've not actually removed a sleeve or drop in as described above whilst underground, but it works in a concrete floor.

 

[pwhole]

I put six Excaliburs into a shaft for temporary belays a few days after this thread popped up and we had a little chat about all this whilst I was installing them - it was good rock and bone-dry locations. We got to a window into a natural chamber with a 6m pitch into it, with two hangers left, and one had to be a backup, as the abseil anchors needed to be beyond the opening. So after a little discussion we abseiled down on one screw. I'm mentioning that more to illustrate the confidence I have in the screws rather than boasting at our death-defying procedures. I'm defintely putting in a second one next trip though! And a traverse across the wall below the roof to get to a possible passage on the far side.