Muir Madness

Post by **marathonmedic** » Wed Feb 23, 2005 10:07 pm

TradMike wrote:The one bolt failure I witnessed at roadside was due to the rock crumbling below the bolt. For the most part it was a horizontally placed bolt in soft stone. The bolt literally sliced through the stone below it. My point is that a longer epoxy bolt would work a little better in that instance.

I'm kind of wondering if that bolt should have been placed if the rock responded like that. Sure hindsight is great, but it sounds like the bolters know hard from soft as they drill.

Rick rocks! Do you have any preliminary numbers about the quantity of force that is breaking these bolts out of the rock? I wonder if it would be possible to test any of the "rotten" bolts out there.

And as long as I'm at it, nobody has been able to give me a straight answer about force on draws during a fall. If I take the standard 20' long whipper, how much force is actually placed on the top draw (i.e. bolt)? And as a sidebar to that, is the friction of the rope through the draw significant to the total force reduction? (thinking of the new roller biners)

Thanks a ton!

Post by **Wes** » Wed Feb 23, 2005 10:43 pm

marathonmedic wrote:
And as long as I'm at it, nobody has been able to give me a straight answer about force on draws during a fall. If I take the standard 20' long whipper, how much force is actually placed on the top draw (i.e. bolt)? And as a sidebar to that, is the friction of the rope through the draw significant to the total force reduction? (thinking of the new roller biners)

Thanks a ton!

It depends on how much rope is out, among other things.

Wes

Post by **Toad** » Wed Feb 23, 2005 11:33 pm

Post by **weber** » Thu Feb 24, 2005 3:59 pm

marathonmedic wrote: Rick ... Do you have any preliminary numbers about the quantity of force that is breaking these bolts out of the rock? I wonder if it would be possible to test any of the "rotten" bolts out there.

At this time, the only numbers I have are from the Swinburne and Australia tests. None for RRG rock. In a few weeks, we should have some data to post here.

The test instrument was just completed. We have yet to take it to Muir. It is essentially a large hydraulic cylinder attached to hardware and a tripod that can be placed over and attached to a bolt, hanger, etc. Then, a hand pump is used to create up to several thousand pounds of force. A pressure gauge is calibrated so that PSI is converted into pounds force.

The testing I've done in the basement is not realistic, nor were forces measured. Just satisfying some curiosities about this sandstone and adhesives. Small sandstone rocks cannot withstand the hydraulic puller. This stuff is really friable with no surrounding rock to support it. The only meaningful tests will be those done on actual rock walls.

Here's a photo of "Arnold" without the tripod and pump:

(The Coke can is in the photo to show scale)

As to your question about testing existing "rotten" bolts in the Red. Yes. But, this is destructive testing. The bolt tested would be history.

Rick

Post by **weber** » Thu Feb 24, 2005 4:02 pm

Oops. Let's try again on the photo.

Post by **pigsteak** » Thu Feb 24, 2005 4:57 pm

is arnold heavy? looks like a bear to carry...

Post by **Alan Evil** » Thu Feb 24, 2005 5:47 pm

How do you power it? And what do you tie it off to? I wanna watch. I'll bring my own safety glasses.

Post by **weber** » Thu Feb 24, 2005 5:58 pm

pigsteak wrote:is arnold heavy? looks like a bear to carry...

Yep -- about 45 pounds with tripod and hand pump.

I was able to keep the weight down by using a surplus cylinder from a B-58 bomber. (Probably cost us taxpayers 10 grand, but I got it for under a hundred bucks.) Unlike standard industrial cylinders made of steel, this one has a case made of aircraft quality aluminum. Much lighter.

We have other bits and pieces that can be used with this setup, including a frame that can be bolted to a wall to hold the cylinder while it pulls on a hanger in a direction perpendicular to the bolt axis.

The cylinder is potentially so powerful (3.5" dia.) , that the hand pump can create forces exceeding the strengths of some of the tester's components like the clevises. So, Arnold can self destruct if not watched carefully. We anticipate failure forces in the 0 - 5000 pound range. The clevises are rated from 9k to 14k pounds (ultimate failure.)

As you can guess, the tripod setup has to be suspended from above so when it pops a bolt and frees itself from the wall, it won't crash down onto the ground.

The hydraulic hose is 12 feet long to get the pumper away from the "action."

Rick

Post by **weber** » Thu Feb 24, 2005 6:02 pm

Alan Evil wrote:How do you power it? And what do you tie it off to? I wanna watch. I'll bring my own safety glasses.

Hand operated hydraulic pump. It pulls with its tripod feet braced against a rock wall directly over a bolt to test pull out. And, it is attached to a frame bolted to a wall beside a bolt to test for "downward" pull.

We will let anyone who is interested in watching know when we will be doing some tests.

Rick

Post by **rhunt** » Thu Feb 24, 2005 6:38 pm

Sunshine wrote:I have asked it before. Have many bolt failures have there been in the Red? I am not talking about loose bolts or bad rock. I am talking about bolts breaking.

I know of one..first bolt on pocket pussy at torrent broke when my friend fell on it. this was year ago before Mark and Kathy..from what I know the bolt just broke right at the hanger. My friend landed on his back with is shoulders hanging over that ledge...he was lucky.