pre-cast piles spacing

huangyhg

pre-cast piles spacing
i'm currently doing a design for the foundation of a six storey building using pre-cast concrete square piles 0.45m x 0.45m x 18.2m long. i have searched through several references and found out that the required spacing ranges from 2 to 3 times the diagonal dimension of the pile.
i would like to know what is the maximum allowable spacing for the piles?
thanks and best regards.
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the maximum spacing depends on your loads, how you will support the loads between the major column/wall loads (are you connecting pile caps with grade beams or will the foundation include a pile-supported mat), the compression capacity of the pile, and the tension capacity of the pile, if needed for overturning or uplift.
as an addendum to my colleague ron, i have used pile spacings in the order of 10 or more with the piles being connected by a grade beam.  why so far apart?  i had 25 ft of soft clay, 10 ft of compact sand and >100 ft of soft clay.  i was founding the piles in the sand and i wanted the spacing large enough so that there would be no overlap of stresses that could be transmitted as a "group" to the clay below.  it worked; haven't heard "boo" from anyone for 13 years.