Pile driving criteria

[Awre]

I need to get more insight into a typical pile driving criteria in this scenario:

A performed analysis concluded a pile tip elevation requirment for an H-pile which will be driven into many clay layers range from meduim to stiff clay layer (layers' avg SPT is 8, 20, and 35)

The questions:
1- Is a vibratory hammer can be used for the H-pile driving?
2- If yes, what is the type of the vibratory hammer that can be used or specified? (rpm, power/force,..etc)
3- How the pile driving criteria is specified "refusal criteria, etc.)"
4- In case the vibratory hammer will not be applicable(?), what are the typical hammer energy, blows per inch for refusal, are specified for impact hammers
5- How can I ensure that the driving stresses on the pile will not be exceeded with any of the above two types of driving.

Thanks

 

[JedClampett]

This thread has been sitting there, so I thought I'd state the obvious. If you don't have a Geotechnical Engineer on the project, experienced in pile design, you need to get one. There's a lot of guidance required in driving piles and you don't want to make a mistake on it. If the pile installers come out with the wrong equipment due to your specification, they're going to want a large change order to make it right.
I am in the final construction phases of a small (512 pile) project, and I don't know what I would of done without our Geotechnical Engineer (I'm structural). The GC tried to change our design based on the design being incorrect (it wasn't) and I couldn't of defended it as well as the Geotech.

 

[Riggly]

adfo,
I agree with Jed - please get a local geotech to help you out. Pile foundations are too costly to mess with. If you only need this info for personal knowledge fine, but I would not advise you to design and establish driving conditions on your own. I have never used vibratory hammer to drive piles, except sheet piles - used automatic hammer, and desiel hammer.

There is a lot that goes into establishing the driving criteria, and this is normally verified by field testing using a PDA(pile driving analyzer). The PDA also monitors the stress in the piles.

* clay with SPT over 30bpf - i would classify as hard - not stiff.

 

[seny]

for open profile H-piles - engineering news formula & diesel hummer. pile capacity must be confirmed by field load test on number of piles according your local code w/ necessary factor of safety to determine allowable load. an after all - just ask your geotech to do his part of job.

 

[Zambo]

You can use a vibro to drive sheet piles, tubular piles or H piles. The effectiveness depends on the soil conditions.

Questions 2-5 depend on the pile design and the soil conditions. General replies wouldn't be helpful.

 

[vulcanhammer]

I agree with the sentiment that you need a geotech experienced in pile design for a project like this.

Having said that, I'd like to address a few of the issues you raised.

On sizing vibratory hammers, I spend a lot of time on the subject at

http://www.vulcanhammer.info/vibro/Vibrator.pdf

I also have a lot of other information on vibratory hammers at

http://www.vulcanhammer.info/vibro/

If you're looking for a specific bearing capacity, a vibro isn't the answer. There's still no accepted correlation between the performance of a vibratory hammer and the ultimate axial capacity of a pile (as opposed to an impact hammer.)

With impact hammer, you're probably looking at a wave equation analysis, and that's where the experienced geotech is a must. PDA during driving will also call for someone who knows what they're doing.

http://www.pz27.net