Page 18 - Unit2.docx

neutral axis of the pile group, then the force on a single pile will be as follows :

……………………………………………3.4

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where:

P = vertical component of the load on any pile from the resultant load Q
v

n = number of vertical piles in the group (see fig3.4)

Q = total vertical load on pile group

If the same group of piles are subjected to an eccentric load Q which is causing rotation
around axis z (see fig 3.2); then for the pile i at distance r xi from axis z:

……………………………………………
3.5

θ is a small angle ∴ tanθ ≈ θ see figure3.4.)

P = force (load on a single pile i
i

U = displacement caused by the eccentric force (load) Q
i

r = distance between pile and neutral axis of pile group;
xi

r positive measured the same direction as e and negative when in the opposite direction.
xi

e = distance between point of intersection of resultant of vertical and horizontal loading
with underside of pile (see figure 3.8)

The sum of all the forces acting on the piles should be zero ⇔

……………………………………………3.
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