Means and Methods for Driven H-Piles 1

[projectEST]

HELP!! Im very unfamiliar with the driving of H-Piles, but I must submit a means and methods procedure to the owner for driving H-Piles.

There will be 162 piles @ 30' that will drive 25' through soil and 5' through rock.

The rock we will hit is serpentine rock which contains traces of asbestos (oh no!)

The procedure must consist of driving techniques, rock augering...

Anyone have any info for me it will be greatly appreciated.

Joe
Project Engineer

 

[GeoPaveTraffic]

Why do you want to "drive" the piles 5 feet into rock?

 

[projectEST]

Excuse me, let me re-phrase that..

We will auger down 30'. Drive down a temporary casing. Pour a concrete socket for the section of beam that will be in rock drive H-Pile in place. Voila!

Piles that go into rock will be "drilled" not "driven"... but I'm sure you already knew that.

Joe
Project Engineer

 

[dik]

Have you checked with safety authorities for working in asbestos? Could bring on a new pile of requirements and regulations... OK as long as the material is undisturbed and not brought to the surface.

Dik

 

[GeoPaveTraffic]

Ok, but same question. Why do you need 5 feet of embedment into rock?

By drilling first and by penetrating the rock you are opening a very large can of worms. I would try very hard to design a foundation system that would not require the removal of material. Of course that is one of the beatuties of driven H-Piles. By drilling first, this benifit of piles is being lost.

 

[projectEST]

We are driving 162 piles of different lengths and different elevation. Some will be driven 15' and wont hit rock. Some will be driven 35' and wont hit rock. Others will be driven 5' and drilled 20' into rock. The elevations, embedment, concrete sockets, lenghts... are all different. I didnt want to specify this due to the fact that I was looking for a simple template regarding means and methods for driving H-Piles.

We are a geotechnical contractor, as you can tell im quite new to this. The engineer is well recognized and designed these plans accordingly.

I need to submit a means and methods procedure and I wanted to see what one for this type of work looked like prior to submitting.

Joe
Project Engineer

 

[PEinc]

Contact the following organizations for information.

For driven piles, try
Pile Driving Contractors Association :

http://www.piledrivers.org/

For drilled casings and shafts, try
Association of Drilled Shaft Contractors:

http://www.adsc-iafd.com

 

[BigH]

Well said PEinc! Always check with reputable pile drivers - they are a great help. I never thought this was so hard!!? It seems that there is no "set" to be achieved - some piles will be end-bearing, some are friction only, etc. given his all over the place. What is he driving into? If in sand, the piles may never set up and you will have to rely on geotechnical calcs to get the capacity. Basically, you get a drop hammer (or diesel), get the pile in place with the leads and pound away. Seems pretty basic to me. H-piles have been driven to and partially into rock for eons of time. You can put on a rock tip on the pile so the bottom flanges don't flay. Don't see why you want to predrill - install H-pile and then concrete - might as well just go with a bored caisson (drilled shaft, drilled pier, drilled-in pile, etc - terms differ but samo samo).

 

[PEinc]

Agree. Also, let's not over-estimate how far piles can be "driven into rock." Frequently, the piles can't be driven into rock. Decomposed or weathered rock, yes but not hard rock, even with points.

 

[GeoPaveTraffic]

BigH and PEinc, both good points. BigH, you specifically said what I was trying to get the initial poster to realize. From his description, they are installing drilled shafts and using a H-Pile as the reinforcing.

 

[Ingy]

I've driven a lot of H-pile and usually you vibrate them in. 25' through soil is no big deal. If they are end bearing then you'll have to vibrate them to a distance of +/- 5' from tip then use an impact hammer to get the required blow counts.
Don't forget to use a template to keep alignment.

Drilling in serpentine isn't as scary as you may think. We do it all the time here in California. Some serpentine has small amounts of friable asbestos. If it is less than 1% (I think) it just goes to the landfill for a fee. If it has a greater amount then you have to treat it like any other asbestos and keep it contained (picture the auger spinning the spoils out in a sack which is then sealed for disposal). 5' into serpentine shouldn't generate too much dirt to worry about.

Why the casing? Are you expecting groundwater or running soils. If the hole will stand you can drill, set, and pour the same day without the casing. Something to consider.

 

[csd72]

Sounds like the asbestos is the critical issue here, find out what means and methods work for the asbestos and then make this work strength wise.

You could do the best engineering job in the world, but if it gets rejected due to asbestos then it might as well be the worst.

 

[Qshake]

It is not uncommon to pre-bore pile especially when it is expected to drive pile through newly compacted material. Also, since the pile are minimal (15') it is not uncommon to use the pre-bore to also bore out a 5' deep hole to set the pile and fill with lean concrete. The remainder of the excavation is filled with loose sand.

This of course prevents down-drag on the piling and the piling aren't actually driven in place but rather set into place. Usually this is OK if you have rock or refusal close to the surface. Since you're setting the pile there is no way to get the bearing.

INGY - I've never seen vibrated h-pile before, mainly due to the fact that most clients require a way of testing the pile. Hence in our area, most h-pile are driven. Only sheet pile for cofferdams are vibrated.

I guess you could use a load test but apparently that doesn't bode well with contractors and so most just drive them.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[oldestguy]

Don't forget to use hardened steel points on piles to go into rock. If you don't belive, me, just withdraw a few of them a look at the tips, if you can recognize them.