Hammer size for driving sheet piles 1

[aeoliantexan]

Our contractor has a problem driving steel sheet piles, and I would like advice on hammer sizing. He is driving pairs of PZC-13 sheets(22 psf) 22 feet long into very stiff to hard fat clay below the water table. He is using a Dawson HPH 1800 hydraulic hammer rated at 7235 to 13750 foot-pounds per blow. He is running the hammer at minimum energy, getting resistance over 30 blows per inch at 17 feet of penetration, and curling the tops of the sheets.

I suspect that a bigger hammer will get the job done. His supplier says that a bigger hammer will simply curl the sheets quicker. What size hammer would commonly be used for this section? A Delmag D-12-30 is available.

 

[PEinc]

Does the contractor have the correct driving head to fit the sheet section he is using? Without the proper driving head, the top of a sheet is not securely contained and can be curled over or torn up. Because PZC sheets are a relatively new product, the contractor may not have the correct driving head (or no driving head at all).

http://www.PeirceEngineering.com

 

[Zambo]

PEinc has a good point - well worth checking out. How are the piles being driven in pairs, are they tack welded together? Why doesn't he try driving single piles? I am a bit surprised that 22 feet long piles are causing such a problem but I'm not familiar with that section and tend to think that with everything unchanged maybe a bigger hammer would just cause more damage earlier.

 

[PEinc]

A PZC 13 sheet is 27.88" wide. A double is 55.76" = 4.65'. This is very wide compared to the width of the impact pile hammer. That means that, without a proper driving head, a lot of energy is being applied to the piling in a small area. This can damage the sheeting. Zambo is correct that you may have better luck driving single 27.88" wide sheets rather than driving doubles. However, you still need the correct driving head.

http://www.PeirceEngineering.com

 

[aeoliantexan]

Thank you for the suggestions. The hammer has a driving head narrow enough to drive single piles. That may well be part of the problem.

 

[PEinc]

From Nebrasks DOT's specs:
j. Piles shall not be driven without the use of a closely fitting cap or driving head. This cap or driving head shall be of such design as to distribute the blow of the hammer throughout the cross section of the pile.

http://www.PeirceEngineering.com

 

[lawayosh]

You want the driving head to spread the impact over as much of the sheet (pile) head as possible. Will overall dimensions of the hammer allow driving singles without interference with adjacent sheets?

Yosh