Hollow Bars Drilling Depth

[crcivil]

For the instalation of self-drilling hollow bars with an outside diameter of 51 mm. and inner one of 33 mm. I need to figure out the capacity of the equipment to be employed. The bars are to be installed vertically in a mass of clean sand, gravels, cobbles and boulders along a river bed. Diameter of drill bit is 115 mm. to go into a total depth of 25 m., drilling and grouting simultaneously.

So far, I have found out that a EMC 350 Track Drill with a VL671 drifter mounted on it might do the job but I haven't been able to get techicanl data concerning such a drifter, so I'm not very sure.

I wonder if some of you have some experience in this construction technique and can tell me if the drilling equipment I'm thinking of employing is suitable for the particular job. Also, I would like to ask you what kind of compressor (CFM, psi) will in your opinion best fit this task.

Thank you, and best regards.

 

[BigH]

While I can't give an answer on the question at hand, it seems that this will be quite difficult given the nature of the river bed - i.e, cobbles and boulders especially.

I am aware, from the 1985 ISSMFE Conference in San Francisco where a piling contractor was to put piles down through material like this, he ended up "blasting" the piling location to break up the boulders and cobbles into sizes he could drive through.

 

[PEinc]

crcivil, first, you should not post the same question in more than one forum. Generally, members read related forums. Therefore, we have seen your question more than once.

25 meters is a long way for an air/percussion drill. The longer the drill steel you are hitting, the less energy goes to the drill bit. If you are drilling very hard cobbles and boulders, the drill bit may not hit as hard or drill as efficiently as you need.

Also, the 115 mm drill bit may be on the large size considering the drill steel length and the hardness of the boulders and cobbles. You might need to use a smaller drill bit.

If I were you, I would talk to the drill manufacturer or supplier to ask about their VL671 drifter with respect to the hole depth, bit diameter, and ground materials to be drilled. Some drifters are more powerful than others and I don't have any drifter information handy.

http://www.PeirceEngineering.com

 

[crcivil]

Thank you for the advice, it is well appreciated.