Vibro hammer piling into silt sand
Vibro hammer piling into silt sand
(OP)
I am currently involved in a project where we will be using an ICE Model 223 vibro pile driver. We are installing interlocking U-section steel piles into silt/sand material with SPT between 35-50. The hammer is old and the company has no records of it being used in the past, what we are trying to find out is whether this hammer is capable of driving into these soil types. I have attached the hammer spec. Any advice would be greatly appreciated.





RE: Vibro hammer piling into silt sand
The real question is not only CAN the hammer do this, but how efficiently can it be done. Having driven piling as a Contractor in the long-ago past, I can assure you that it is very possible to install piling with a hammer that is "too small", but what Contractor can afford to stand-by all day (literally) to drive one sheet?
Sorry that I cannot give you a better answer, perhaps someone else can - just want offer this suggestion so that you get the information you need to make an informed decision.
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RE: Vibro hammer piling into silt sand
http://www.vulcanhammer.info/vibro/Vibrator.pdf
I should emphasise that these are just that: rules of thumb. Selecting a vibratory hammer is very much an experience based business.
The document you referenced is damaged, but ICE's site has the specs at
http://www.iceusa.com/223-335e.htm
What's very interesting about this hammer is that it is a "high-frequency" hammer. I outline our (Vulcan's) experience at
http://www.vulcanhammer.info/vibro/
We saw these hammers used in cohesive soils very frequently, but the big drawback to a high frequency hammer is that the amplitude isn't as great for the same dynamic force from a lower frequency hammer. That amplitude is important for elevated toe resistance, even with low displacement piles such as sheeting. In that situation a lower frequency/higher amplitude hammer will use the whole pile as a rapid impact hammer; the longer the "stroke" (amplitude) the more the system can overcome toe resistance.
Another important factor is the water content of the soil. A saturated soil will facilitate vibratory driving at any frequency, particularly with cohesive soils.
RE: Vibro hammer piling into silt sand
Rate of installation was good but at some locations we could not drive the full length. All piles were either fully or partially installed using the vibro. We then brought in a pneumatic hammer to complete the driving where the vibro had been unable (or just too slow) to drive the full length.
RE: Vibro hammer piling into silt sand
Do not forget that the vibrations caused by the vibrohammer will compact the soil furthermore if it is a clean sand ( which is likely to be given the N values )
RE: Vibro hammer piling into silt sand
RE: Vibro hammer piling into silt sand
If you are only driving you may want to ask ICE to supply you with a bias weight for the hammer. This is a saddle weight that fits over the suppressor housing and helps the hammer drive a little better. Since it is on the suspension, it acts like a crowd force on the gearbox. In my experience, these weights cost very little to rent or purchase. If you are renting the hammer from them you may get it thrown in for free.
Good luck. Let us know how it goes.
RE: Vibro hammer piling into silt sand
RE: Vibro hammer piling into silt sand
Are you a contractor or a consulting engineer? If an engineer, talk to a local pile driver for recommendations or specify a minimum section modulus and let the contractor pick the sheet size he thinks is drivable. If you are a contractor, you should already have a feel for the needed size. If you are a contractor and will need to buy the sheets, pick a heavier sheet that can be extracted and then be re-used on most other projects. If you intend to rent sheets, your choice will probably be limited to heavier sheet sizes. Suppliers usually do not rent light weight sheet piling.
RE: Vibro hammer piling into silt sand