Can hollow stem augers drill through rubbles of concrete? 2

[fyaure]

Can hollow stem augers be used to grout shafts in subsidence areas? Is yes, is there any specific minimum rig size?
Also are these able to drill through all kinds of rubbles including concrete?

 

[rchanke]

We need more information to answer the first two questions (ground conditions, drill depth and orientation, grouting technique etc). What is it exactly you are trying to do?

To answer your third question, hollow stem augers do not like rock, concrete or rubble. I've drilled through silt-sand-clay stone using continuous flight augers with a large rig with lots of down crowd but not anything extremely tough,,, and not with hollow stem augers, which inherently have a greater diameter than conventional CFA therefore require more volume of the drilling obstructions (rocks/concrete) to be removed by the auger flights.

If you are looking at using the hollow stem to enable putting a grout pipe or some other product down hole then look at using one of the many duplex type systems available. Rotary percussion with either top or bottom hammer to get through the given drill obstructions to advance your casing to the desired depth. Once at depth, one can trip out the inner drill string leaving you with a cased hole.

Which ever system you choose, I'm sure your driller will ever so politely let you know on the quality of your decision.

 

[BigH]

rchanke - nice post
I agree - hollow stems are not the way to go - mucho damage to the augers. Percussion drill is likely the best - didn't say if there were possible caving problems in uncased hole - might not even need casing depending on concrete rubble infill if any.

 

[PEinc]

Agree with rchanke about the rotary percussion drill. Rubble could trap a regular percussion bit if rubble pieces fall into the drill hole. The rotary percussion drill can drill and case the hole at the same time.

 

[fyaure]

Thanks rchanke for your valuable advise. Since I don't know what's inside the mineshaft, I will try with hollow stem auger(previous experience on site shows the rubble might be soft enough). In that case, I would like to know if the same auger stem could be used to pressure grout the mineshaft (which could be about 70 feet deep) with upstage grouting technique (starting from the bottom and pulling out as the shaft gets filled).
However, in case hard rock is encountered, percussion drilling may be needed. Is it possible to put the percussion drill rod and bit through the auger stem? - and then installing casing underneath. How about placing the packers in the stem?
I know this is going to be a very wierd combination but some drillers may be able to tell me if it is possible.
I am looking for a cheap method and save work too.

 

[GeoPaveTraffic]

Pressure grouting through the hollow stem is possible, assuming that the soil/rubble on the outside of the stem is solid against the auger. Otherwise the groute will travel up the outside of the auger when you apply pressure.