Pile Spacing

Most of the Spec called for "Piles in group, if required, should have a minimum center-to-center spacing of 2.5 times the pile diameter, but in NO event less than 3 feet on centers." I understand that 2.5XDia is for group effect but can someone outthere plese expain to me where the 3 feet came from? Thanks a lot!!

 

[KAM_imported]

Optimal spacing is usually 2.5 to 3.5D, where D= pile diameter. Some codes also specify a minimum spacing of 24 to 30 inches (regardless of pile diameter) so this may be where your "3 feet" came from. Ideally, the piles should be spaced such that the load-carrying capacity of the group is not less than the sum of the bearing capacity of the individual piles.

 

Thanks! KAM

 

[kay]

this is too late in the day maybe, but pile spacing is supposed to take cognisasance of pressure zone influences especially for friction type piles.

while min. spacing is recommended, often 3.14D ie pie *D an optimal spacing is necessary to achieve an economic pile cap.

Spacing requirement is not very critical for end bearing piles.
Also, for friction piles, there is a pile group efficiency component for the pile group action, depending on geometry of installation etc.(Feld's rule)


kay