Coring Through Concrete and Rubble

[CapeBreton]

Has anyone ever been involved in a project requiring drilling through reinforced concrete, passing through rubble and drilling through concrete again? The goal is to
install rock anchors of a length of 35 feet.

 

[ishvaaag]

Drilling equipment for anchors must be able to do that. If the rubble is too loose they will be using casing, that, on the other hand, is usually left in say 18 ft embedded in the ground to provide some length for free extension of part of the cable or bar anchors, at least for installation time.

 

[BigH]

use an air-track - mining drill.

 

[dirtydude]

It can be done, but the reinforcing in the concrete will be the most difficult part. If there are as-builts of the existing concrete and the reinforcing can be avoided, then that would be best.

 

[cvg]

a tri-cone rock bit should have no problem with this. talk to a driller.

 

[born2drill]

A few questions:

1. Is the top reinforced concrete layer exposed?
2. How loose is the rubble layer? Will it need to be cased?
3. Is the 2nd reinforced concrete layer sitting directly on top of competent rock?
4. What is your anchor design load and the anticipated hole diameter needed?

If you need to case through the rubble, forget using an airtrack. For drilling through reinforced concrete, I would not pick a tricone roller bit as my weapon of choice.

If the top reinforced concrete layer is exposed, I'd recommend coring through that to the rubble. You'll most likely have to case your hole through the rubble. Also, casing is installed to prevent hole collapse. It may even be temporary. Free length should be provided by sheathing the anchor tendon above the rock socket.