Page 26 - Unit2.docx

Figure 3-7

NB : The horizontal force, H, imposes a torsional force on the vertical piles.

Sum of forces on a single pile = Q + H + M

as a result of Q: P vi = Q/n

as a result of H: P vi = - H/(n tanα )
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as a result of H: P ri = + H/(m sinα )

as a result of moment M:

r i measured perpendicular to the N.A of both the vertical and raking piles

Example 3.3

Figure 3.7 shows a pile group of vertical and raking piles subjected to vertical load Q =
3000 kN and lateral load H = 250 kN. Determine the forces acting on each pile. The
raking piles lie at an angle of 4:2.

Solution:

First we determine the location of the neutral axis, N.A, of both the vertical piles and the
raking piles. From figure 3.7 we see that the number of vertical piles = 8 and the number
of raking piles = 4

2. N.A for the vertical piles is determined as follows:

Here we assume ¢ through piles a2, a2, a3, a4 as a reference point and start measuring in
the positive direction of the X axis, where it is denoted on figure 3.20 as X-X