Marking out for piling and piling cap height?

[Delinquent]

I've got the piling team starting Monday - all is pretty much ready for them but just wondering what is the "professional" method of marking out where the piles go? I've put the line markers in place and strung everything up, At the moment I've just stuck a tent peg in the centre point of where each pile needs to go as that's all I had to hand!

Now... once the piles start going in, what is the normal procedure in terms of setting a height for them to finish them at, and then "capping" (Capping is a term I've only heard from the piling company - no idea what it means ) I've worked out where the top of the piles needs to come using my Datum point, but how do I illustrate this to them and account for the caps or do I just leave them to it?!

Cheers!

ETA - just been doing more research on pile capping and it appears to be something to do with spreading the load over several piles - as I'm just having a ring beam going on top of the piles, do I even need to worry about this?!

 

[Shytalkz]

There should be a drawing from the SE showing pile setting out positions. The indivdual positions are usually set out with a pin (piece of rebar); the piles should be positioned within ±75mm of that position.

Presuming that the piles are driven steel-cased concrete, the casings are driven to a pre-determined set of x blows/inch. The top casing is left where it stops and the pile concreted. After the concrete has gone off, the pile top is cut down to a level relative to the site datum and which ensures that the pile penetrates min 450 either into the beam (for single piles) or a pile cap (for two or more in groups).

Who cuts the piles down depends on the contractual arragements: if the piling company are also doing the ground beams, then they will do it; if you're doing the beams, generally it will fall to you to do. There are circular cutting tools that can clamp to the pile to give a clean cut at the required head level.

 

[Bowness72]

450mm pile projection into beam sounds a lot. Is that just for the type of pile you assumed or am I missing something ? I am by no means a piling expert but normally assume 75mm concrete projection with appropriate reinforcement projecting further.

 

[Shytalkz]

Typo alert! Meant 50mm with min 450mm of pile rebar above that level. My mind was obviously elsewhere...

 

[noseall]

Typo alert! Meant 50mm with min 450mm of pile rebar above that level. My mind was obviously elsewhere...

tut, tut, tut!

you need to get a grip Shy.

 

[Shytalkz]

tut, tut, tut!

you need to get a grip Shy.

I probably was....

 

[Delinquent]

Just bringing this back up to say thanks to Shytalks for the info - just looking back over my threads for something else and realised I'd forgotten to do so - How rude of me!!

 

[Shytalkz]

No problem, glad to be of help