Auger Cast Pile Spacing 6D/3D

[Boiler106]

IBC 1810.4.8 specifies that auger cast piles shall not be spaced less than 6 x Dia from an element less than 12 hrs old.

My question is whether or not its practical and constructible to do 3 x Dia spacing for 16 inch dia auger cast piles, while adhering to the 12 hour rule.

Piles are end bearing.

Thoughts?

 

[JAE]

3 x pile diameter is what I've had recommended to me from geotechnical engineers for many projects...of course assuming 12 hours or more cure time for them.

For drilled piers (end bearing) we've even been allowed 1.5 x diameter with a 50% reduction in capacity.

I'm sure this depends on the type of bearing strata you are dealing with, though. Need to consult with your geotechnical engineer.



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[jgailla]

Boiler,
What I've seen is that the drill rig(s) skip across the project from one location of closely spaced piles to another so that it is more than 12 hours between pile drilling. IBC is prescriptive in this matter. I haven't been on any projects where there haven't been enough locations of closely spaced piles to hold up the drillers.