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Don't place bolts near cracks

Posted: Mon Feb 10, 2014 3:19 pm
by Justin
FYI :cyclops:

Don't place bolts near or next to cracks (even small ones).

Re: Don't place bolts near cracks

Posted: Mon Feb 10, 2014 5:46 pm
by pierre.joubert
Or use electroplated mild steel bolts for that matter

Re: Don't place bolts near cracks

Posted: Mon Feb 10, 2014 11:08 pm
by NatureBoi
5” (127mm) from old bolt
6” (153mm) from fracture
200mm away from an edge
Rap anchors/ Lower-off's: 200-300mm apart,

Re: Don't place bolts near cracks

Posted: Mon Feb 10, 2014 11:11 pm
by Justin
Thanks Cormac.
Was just going to comment that the crack could have been caused whilst drilling or whilst hammering the bolt into place.

Pierre: Why do you think a softer/different bolt would make a difference?

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 8:39 am
by emile
I think he was continuing on the "Don't......"

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 9:27 am
by pierre.joubert
I mean
Also, don't use electroplated mild steel bolts for that matter

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 9:43 am
by BAbycoat
Xenomorph wrote:5” (127mm) from old bolt
6” (153mm) from fracture
200mm away from an edge
Rap anchors/ Lower-off's: 200-300mm apart,
Are these specs for expansion bolts only, or glue-ins too?

I have a nearby (non-RSA) route with lower-offs of dubious quality slap-bang in the middle of the only decent placements. Struggling to figure out how to re-bolt with good glue-ins without going too close to edges, fractures or existing expansion bolts.

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 10:05 am
by Justin
emile wrote:I think he was continuing on the "Don't......"
Got it.

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 12:41 pm
by Chris F
Justin wrote:Was just going to comment that the crack could have been caused whilst drilling or whilst hammering
Smaller ones maybe but the main crack (running diagonally on the left) looks like it was there for a while. How old is the bolt?

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 12:51 pm
by Justin
For sure, the main crack running down left has been there for a long time.
The bolt was placed in 2002.

Re: Don't place bolts near cracks

Posted: Tue Feb 11, 2014 1:26 pm
by Andy Davies
Rule of thumb based on the Fischer handbook is bolt >1.5x anchor depth away from edges and cracks. When rebolting routes we are often constrained with old bolts, so usually try and keep it >1.0x anchor depth away from old bolts.