group action in piles

[ketanco]

I was solving a question for PE preparation about piles. it calculates the perimeter of each pile and the the perimeter of a two pile group and since the preimeter of group is bigger, it says no group action reduction is needed.

so does it mean the group action means a reduction with respect to sum of individual capacities, and only if the perimeter of group is bigger than sum of individual perimeters there is no reduction? so in other words, at best, you can get the sum of each pile with group action and it can not be more than the sum of individual piles?

 

[oldestguy]

The perimeter analogy is meaningless. For example, fill the space inside the group with more piles, so that they sit against each other. Then the stupid method is very evident. What you should be looking at is the zone of soil supporting each pile. If those zones overlap, then you need to look at the group as one unit.

In going for PE exam as you apparently are now trying, I wonder if maybe you should have had a good course in soil mechanics first. Questions like this make it appear you never took such a course.