I am carrying out piling, 350mm x12m and 450mm x12m spun pile, having installed length of 50m to 60m
My problem is maintaining the straightness of the pile to within 75mm in all direction
The diameter of the end plate against the length of the pile eg for 350mm and 450mm pile ratio of length to diameter is 34.28 and 26.66
Notable here is that if the surface of the end plate of a pile deviated from true 90 degree against the shaft of the pile by 1mm , this pile will be tilted 34.28mm or 26.66mm when a flat plate to plate welding is done between the end. in this respect, installing a 60 m installed length of pile will theorically have a deviation of 171.4mm and 133.3mm deviation.
Unfortunately, I have found that each pile have such deviation of approximately average of 3mm, aggrevating the problem to 857mm or 666.5mm.
Off course this is the maximum theoritical state and sue to compensating factor, it will always be less.
I am in Malaysia and found that 3 such factories producing spun piles have piles of this tolerance (averaging 3mm
I shall be happy to understand what is the tolerance of the piles manufacturers of others countries and what is being done in spun pile installation to keep the piles straight.
I'm in the pile manufacturing industry so this is not new to me.
As far as I know, the tolerances in the joint plates will soon have to follow the Malaysian Standards tolerances. I was in the committee for MS 1314 part 1 to 6 in an on and off fashion and if I can remember, it was actually the manufacturers that proposed for a 5mm permissable tolerance!
In real life, if the end squareness has deviated by a small fraction (<5mm), then the pile (which is not perfectly rigid) will deform to close this gap under load. Unofficially in practice, small thin steel plates are inserted before welding to compensate where the gap is large.
If deviation is observed to be consistent = check pile mould. If deviation is observed to be inconsistent = varying prestress transfer from tendon to pile (rare but has happened before). If pile banana shape = same as above.
Please note that the pile end shape often depends on its mould. Cepco and ICP's moulds are designed very rigid to resist deformation but can deform with time and use.
I hope I have been of help. I apologise for my unpracticed english.
if you want do the joining,lets the pile protude as long as you can.so you can see the shaft of pile below.just make straight to the joint pile by use theodolite.tilted the theodolite follows the tilt pile under ground.you can see the line of pile.do not follow the pile head.