piling using the vibro method

[llo]

A platform designed to be carried on piles in shallow water with each pile having a designed capacity a 40tons. Due to construction difficulty a piling hammer would not be suitable for the construction. However a vibro method would suffice, my problem is since the hammer efficiency is greater than the vibration method . Would the penetration depth be the same in both cases?. How do I establish a refusal/ acceptance criteria??

 

[Focht3]

Hmmm,

Impact driving isn't always more efficient than using a vibratory hammer, at least when it comes to the final product - an installed pile.

Where is your site? What brands and sizes of drivers are available to you? What type and size pile are you installing? What are the subsurface conditions?

We need a lot more information in order to assist you...



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[llo]

my site is in nigeria (swampy land)

for now i (client )don't Have the specifications of the equipment, I just know that a group called Trevi foundations would carry out the site construction. Initial designed piled sizes are 407mm and 273mm in diameter( 40 tons each) to a depth of 30m below water bed to a max pile length of 35m with 2/3m penetration in to a suitable soil strata . A proposal to change this to 355 and 508mm in diameter. The 508mm are to replace the raked piles. Theoretically all have being reviewed and agreed. My question is that would the vrbrohammer achieve this depth. What are the guide lines achieving this refusal / acceptance criteria .

 

[Focht3]

I assume that a proper geotechnical study has been completed, and that you have a strength profile that was used to design the pile foundations. If this assumption is correct, then the acceptance criteria is quite simple: the piles must be installed to the specified depth. Period.

If you don't have a proper geotechnical study, get one. Before you start installing the platform - not after it begins to fail...



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[DRC1]

To go that deep with a Vibro with fairly large diameter piles will require a large Vibro. You can do a static capcity analysis to determine bearing depth. Difficult to accurate bearing capacity from vibro. Can restrike with impact hammer and PDA to get capacity. Are you sure you need to go so deep with such big piles for 40 tons? Also, 1.) Driving such large piles with either a vibro or an impact will require a lot of energy which will effect nearby strucures and excvations and needs to be considered. 2.)Be careful how you drive piles as soil may tighten or loosen as you drive these piles
3.) You don't specify the batter for the batter piles but some template system may be required to keep the piles from walking.
Again, I would look at the size and depth of you piles if you are only trying to get a 40 ton working load.