This post is still incomplete until I get access to more of our destructive testing data. The numbers here are off the top of my head.
We spent the last day of the course doing what cavers do best: breaking shit.
Quarry day had a few different stations:
- Pick-offs at fixed anchors and by cutting the patient’s tether
- Different diameters of rope for SRT (10.5mm down to 6mm)
- Bolting (ranging from hand-drilling spits to doing it the new-fangled way)
- Different kinds of hardware (spits, glue-ins, wedge bolts, screws, Petzl Pulses)
- Tensioned high-lines
- How to rescue someone in a J-hang
- Destructive testing
- Aid climbing theory and considerations
At one of the pickoff stations, we cut our patient’s top ascender tether (long cowstail) with our wrench tether. Jonathan attempted this technique on me, but since he had injured his shoulder trying to brute-force lift Derek Bristol with one arm during a pickoff a few days before, he did so with an improvised bow saw. Jokes aside, his method was surprisingly effective. Unfortunately, it was the only effective part of his attempt, and my hips suffered dearly.
Once I get access to the data, I plan on writing more about the specifics of the destructive testing we did. We spent our lunch break doing drop tests with a dynamometer onto a variety of things (fall factor 1 onto a croll on 6mm probably being the scariest).
The last part of the day was spent doing pull-tests on a wide range of different anchors. It absolutely blew my mind to see an 8mm multi-monti screw in horrible rock still not fail until 18kN. I knew screws were good, but damn! They outperformed almost every other anchor we pull-tested. We played and played until we eventually broke the testing apparatus (Sorry, Zsolti!).
At that point we broke out the big guns, and pulled a dyneema drill-thru anchor with an industrial-sized come-along. At some point (the kN fail me), the rock failed, but the dyneema showed no signs of strain. I thought the French were crazy to use so many drill-thru’s (and they still are, for other reasons), but that test changed my mind.
Thanks again to Ági and Sam for use of their photos, shamelessly harvested off Facebook and from our shared photo album.