Minimum Pile Spacing and Group Effect
Minimum Pile Spacing and Group Effect
(OP)
Generally, Pile Spacing is limited to a minimum of 3 X Diameter.
Question: I have a case where the Pile Spacing is less than 3 X Dia. (approx. 2-1/2 X Dia.), and the Group capacity exceeds the sum of the individual pile capacities, therefore, the individual pile capacity is used as the limit for each pile load.
In such a situation, is a reduction of the individual pile capacity required due to the spacing?
Question: I have a case where the Pile Spacing is less than 3 X Dia. (approx. 2-1/2 X Dia.), and the Group capacity exceeds the sum of the individual pile capacities, therefore, the individual pile capacity is used as the limit for each pile load.
In such a situation, is a reduction of the individual pile capacity required due to the spacing?





RE: Minimum Pile Spacing and Group Effect
You will probably note that even for large pile spacing, say 10 pile diameters, the formula still shows group efficiency lower than 100%... that's one indication of the limitations of these calculations. Use them with that in mind.
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RE: Minimum Pile Spacing and Group Effect
I simply calculated the Pile Group Capacity based on friction along the perimeter of the pile group block.
It seems the Converse-Labarre equation is more conservative (33% less Group Efficiency).
However, what I was trying to determine, is this:
The Pile Group Capacity exceeds the sum of the individual pile capacities.
Therefore, Individual Capacity governs and the capacity of the group = Sum of Individual Piles.
In this case, is any reduction factor (even if Group Efficiency > 1.0) required simply
because of the pile spacing?
If so, that would imply there is an upper bound pile capacity somewhere between the individual capacity and the (group capacity divided by no. of piles) as a function of pile spacing.
RE: Minimum Pile Spacing and Group Effect
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