Guidance required on Sheet Pile De-Clutching forces

[Grahammachin]

I have posted this in the geotechnical earth retention engineering section but thought I would post here to hoping I could get a response.

I was wondering if anyone could give some guidance on the following:

1. The forces required to declutch a PU32 pile, as a result of the moment applied to the pile?

2. How to calculate the forces in the clutch as a result of the moment?

3. How to calculate the shear capacity of a clutch on a PU32 pile (horizontal shear not vertical)?

The piles have been driven without the clutches being welded up (don't ask...), how much will this affect the load capacity of the piles.

They have been driven to bed rock in clay soils.

 

[Zambo]

I don't know the answers to your questions, but I wonder why you want to weld the clutches. Are you talking about fully welding the clutches or some tack welds?

Were the piles driven individually or in pairs?

What kind of panel driving sequence were you using - by this I mean were you setting up the piles in a frame above ground and then driving or was each pile set up individually.

Have you excavated yet? Any sign of leaks or movement?

 

[Grahammachin]

As I understand it, the piles were driven individually not in welded pairs (I have been told this is standard practice in the UK though I can't for the life of me understand why).

As for the sequencing and piling method I have not been told. The piles and piling were spec'd by our geotechnical engineers and they have asked me to look into the de-clutching issue.

I don't know if they have started excavating yet (I would of thought they would of by now as they are asking for the reinforcing drawings for internal structure). No one has said there is any leaking or movement.

 

[Zambo]

Are the sheet piles for temporary works or permanent works i.e will the sheet piles be extracted and re-used on another project?

Is the welding shown on the geotechnical engineer's drawings?

Just out of interest how old is the geotechnical engineer?

 

[PEinc]

By de-clutching, I assume you mean separation of the sheet pile interlock. Correct?

Why are you worrying about this problem? Is it happening or is it a potential problem that someone is obsessing about? I've designed hundreds of sheet pile projects and have built many. I've never seen hot rolled interlocks separate except when the sheets were being driven into underground obstructions.

 

[Grahammachin]

Just had some clarification on the problem.

We have 900kNm moment in the pile and they are worried about the in-pan and the outpan sliping in relation to each over vertically as a reuslt of the moment.

Does anyone have any guidance on how to calculate the shear force that I would need to resist

 

[PEinc]

I've never seen that considered in a sheet pile wall design.

 

[Grahammachin]

Yeah thats what I thought but the geotech guy mentioned it to the client and now they are getting jumpy.

It all started when they realised that the groundwater pressure was so much higher than they had designed for so had to redesign.

This is all temporary checks as the cofferdam is going to have a concrete pumping chamber cast into it.

 

[PEinc]

Ask the geotech what he's talking about and ask him for a reference that addresses the "problem."

 

[GBTDS]

Actually for the best support on this question contact the nearest office of Arcelor - they have a complete engineering department and have fully tested their own sheet piles and know what stresses will fail the interlocks.