Driven Stakes as Rappel Anchors

I am searching for any published results recording the holding strength of stakes driven into the earth as rappel anchors, preferably substantial metal anchors.

Why on earth would I want such data?

I am a retired NPS archaeologist, last assigned to Channel islands National park.  There are extensive sea cliffs and canyon walls carved from unconsolidated Pleistocene sediments which contain fossil remains, typically pygmy mammoth, that re best recovered by rappelling from the flat, grassy surface above .  I have done this numeroustimes, using three stakes in a triangular configuration

i use mil surplus stakes, allegedly used to jold down Marston matting in helipads, about a meter long with a U shaped cross section about 5 cm x 7 cm.  These are typically driven about 45-50 cm deep into good compact soil at a slight incline.  I have set up this anchor configuration numerous times (50 =/-) and I have never observed any sign of incipient failure.

I would like to learn of any controlled tests that might have been performedon arig of this type.  i have read informally of such tests being run at Golden Gate Recreation Area (San Francisco), but inquiries there have come up empty.

BTW, I would never do this for any purpose other than to collect material otherwise unobtainable.  The sea cliffs are choss piles squared and a helmet is absolutely mandatory, even after clearing off the larger pieces.  Over time, we have acquired some very significant specimens on rappel which would otherwise rapidly disintegrate.

Comments, leads, references, and comments are appreciated.  Thank you very much in advance

Scroll down here:

http://bolt-products.com/Glue-inBoltDesign.htm

Jim Titt has this sort of info on his web site.

http://www.bolt-products.com/Glue-inBoltDesign.htm

Don, in the "leads" category:

• Canyoneers and alpinists often construct roughly this style of anchor and call it a "deadman." Here's a basic rundown: dyeclan.com/outdoors101/can…;
• Alpinists also have "snow pickets," which are used to construct a variety of anchors in snow, several of which could be categorized as "deadman" anchors. MSR makes the industry standard picket and might have some answers to your questions if you get in touch: https://www.msrgear.com/snow-tools/snow-anchors/90-cm-snow-picket/10950.html 
• We also use "flukes" sometimes, though they have fallen out of favor: https://www.msrgear.com/snow-tools/snow-anchors/snow-fluke/snow-fluke.html

Your local or national canyoneering club is likely the right contact for this question. Here in the climbing world, we want every anchor to be able to hold a pickup truck dropped from a mile up; by contrast, those rowdybois who run canyons would rappel from dental floss wrapped around a loose thimble without batting an eyelash.

For multiple stake systems you should check military manuals, they build them for heavy vehicle recovery anchors. We only ever use single (,or rarely double) so I never tested anything else.
A friend of mine uses a DMM Talon which is designed for rescue purposes and there are test results available somewhere.
My brother and I use two 18" lengths of 2" alloy angle one behind the other (the proper way to do it, forget Vees).

There is this but it only applied for anchor placed in snow (with a recap spreadsheet at the end) https://www.youtube.com/watch?v=yYtYZgeUpek

I'd drop a YGD on you, but you sound like you know what you're doing!

I don't have an answer to your question but sounds like great fun.  I've bagged Silver Peak on Catalina a few times.  The wilds of the Channel Islands are a treasure.  

I learned to climb and rig for climbing and rappelling in the 1970's.  The question you have to ask youself with each knot or anchor is, "do I trust my life to this?"

My crew used a similar anchor setup for rappelling while working in Mesa Verde National Park over a decade ago. I have to admit that it scared the crap out of my fellow climber friends, but the anchors always seemed super bomber.

I wonder if commercial high angle scaling/rescue companies or their suppliers would have the data you’re looking for. 

Skinner Butte in Eugene used to have a couple of stakes driven in the soil behind the basalt columns for top rope anchors. There were used for years. Don't know if they are still there (30+ years).

its a common anchor method in Iceland for ICESAR. they basically pound rebar into the ground for anchors...

granted, they are dealing with different soil gradients than here, but the method isnt entirely unheard of...

Some possible leads:
https://www.cmcpro.com/equipment/hurley-picket-anchor-system
https://hogantentstakes.com/rescue-pickets/

Really good resourse Tammy.   youtube.com/watch?v=-RrtcBN…  (video as linked above in previous post)

The 1-1-1 is very common sense.  If you are in a system where a picket is showing failure, you immediately back it up in that way out of desperation.  I figured this one out while anchoring the ends of a monkey bridge (rope bridge) for Boy Scouts.  

It's valuable to know this because if you didn't, and you were used to normal belay station climbing anchors were you equalize 3 anchors spread out, the system would not hold the load that the 1-1-1 system  could hold.

Don, are you still in the Ventura area? In Ojai there is foothill crag. There are some large stakes or “big bolts” leading up to the cave halfway up the crag. Are they kinda what your talking about? Those things are mega bomber, I’d dare say you could hang a truck off of those

Tammy Gueterman wrote: Tandem pickets are used in rope rescue usually 3 in a line "1-1-1" each tied back. Originally, circus tent stakes were used, but now there are now purpose built stakes and plates that replace the tieback webbing. Sort of like anchoring to trees and shrubbery, you'll never have a engineer out there telling you how much a particular system is rated but typically they are good for several thousand pounds. I haven't found good published data and I'm not sure if it exists since the strength depends on the soil. In this test in rocky desert soil they pulled 6000 lbs and the pickets didn't budge. They also did a test on the plate version with similar results. I also prefer this rigging method to pretension all of the pickets and the interleaved webbing makes it redundant against failure of the first picket.

I looked at one of those videos and began to wonder how they got the stakes back out.
Is there an easy method, or just a lot of hammering back and forth to widen the hole?

In my experience, removing the stakes is quite straightforward.  Tap a few times sideways, then tap the opposite way and you can then just pull the stake right out.  Soil type undoubtedly makes a difference

To respond to Jeff Luton's post:  I haven't been to Foothill crag recently, but those would be placed in (relatively) solid rock, kind of mega pitons.  i am talking about stakes in soil, and then loaded laterally.  The references given earlier seem to indicate rather decent holding power around 1000 pounds per stake, no matter how aligned.  This is indeed helpful and reasonably reassuring.

I've done a good bit of research on this topic. I'll try to give you an unbiased opinion but full disclosure I designed an anchor plate and picket anchor system you've already seen on this thread. The most robust data comes from the Industrial Fabrics Association International and the University of Illinois "Pullout Capacity of Tent Stakes" They made a pretty good pocket guide here http://tent.ifai.com/wp-content/uploads/sites/16/2016/06/trd_2014_stakingpocketguide.pdf

The vast majority of the time your holding power is much more dependent on your soil than the apparatus you use but you can certainly maximize the capacity but paying attention to stake configuration, diameter, spacing, insertion angle and insertion depth.

Personally, I've pulled picket systems to failure hundreds if not thousands of times and I use the term "failure" as any time there is more than 2" movement in a system from where it started. I'm sure a slow rappel won't give you problems in just about any ground and in several different picket set-ups but I would be concerned about a shock load from a fall. Happy to answer any additional questions. - - - James HeavyRescueSolutions@gmail.com