Rebar use as "Soil Nails" 1

[corrosionman]

Hello, My domestic garage ( 35 years old) is built into a sloping ground and the rear wall now showing a few cracks due to external ground pressure. I'm thinking of strengthening the wall by drilling through the wall and then driving in a number of "soil nails" made from sizeable rebar, driven in to about 20 ft length. I would finally weld on short threaded pieces that will accept the retaining nuts and a retaining plates. A very thick rubber pad will be placed under the retainer plates and the amount of " Squeeze" will show the force being applied by each nail.The rebars will be hammered in by a concrete breaker which is itself pushed by a telehandler 3 ton ram.The leading end of the rebar will be pointed. The local ground is a very hard clay and
The uncertainties in my mind are :-
If the nails are pushed and hammered till no more movement can I assume that each will then permamently resist being pulled out again provided the withdrawal force is only half of the driving force.
After the nails are driven in, will the ground ( Clay) eventually settle around the rebar and grip it more tightly or would it be better to use straight round bar rather than rebar.
I would greatly appreciate any comments, ideas and criticism.

Corrosionman

 

[kieran1]

What makes you think the cracks are due to external ground pressure, if the wall has performed its function for 35 years?

Even if the cracks are a result of ground pressures, would it not be easier and more reliable to provide remedial works on the outside face of the wall?

Kieran

 

[PilebuckEngineer]

I've done a lot of soil nails in the field and you usually need to drill, then stuff the rod, then grout and some times post-grout to get the strength you need. If you have a design load you just put a center hole ram on them and you can verify strength, creep, movement, etc. I wouldn't use rebar with a welded rod. Most high strength rods will get brittle if welded too. I would just use a threaded rod the whole way. Like a dwidag bar or williams coil rod.

 

[csd72]

Pullout capacities of these types of things are generally a small fraction of the insertion force.