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Chockstone Forum - Accidents & Injuries

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The 9-Feb-2009 At 11:00:47 AM AndyRicho

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Neil, i don't think we should be making comparison's in the safety of carrots to that of the bolts used on the Croatian route, but thanks for your diagram as it will make what i'm about to write a little easier to understand.
As most would of seen on you tube by now these bolts came out very easily. While Simon and Mike were doing this footage i made my way down to the base of the cliff and removed a large number of bolts. What i found with ALL of them was they had little or no expansion, even after being tugged out with my hammer. I took some measurements off a bolt that had NO movement on 1 sleeve and the other had moved 1.8mm. The sleeve that hadn't moved measured 8.7mm at it's outer side and 8.3mm at the side that slides up the cone. These sleeves will compress slightly when the bolt is tapped into the correct sized hole in solid rock and have good contact with the rock when tightening to create good holding power. However the sleeve that had moved still measured 8.7mm at it's outer and 8.4mm at the side that slides up the cone. Almost NO expansion has happened at all. At this point clearly the force needed to hold the sleeve for expansion was less than that to crumble the rock in front of it and the bolts come straight out.
Sorry if my explination is a bit hard to understand but basically this style of expansion bolt just does NOT work in soft rock