Page 63 - Unit2.docx

S = pile centre to centre distance (spacing)

Example 7-2

A retaining wall imposing a weight of 220kN/m including self-weight of the pile cap
is to be constructed on pile foundation in clay. Timber piles of 250mm in diameter
and each 24m long with bearing capacity of 90kN/st has been proposed. Asses
© It's Engg. Life
suitable pile spacing and pile arrangement.

Solution:

2. recommended minimum pile spacing:

S = 3.5⋅ (d) + 0.02 ⋅ L = 3.5 ⋅ (0.25) + 0.02 ⋅ 24 = 2.26 m ♥

2. try arranging the piles into
two rows:

vertical load = 220kN/M

single pile load capacity =
90kN/st

∴ = 2.33m

spacing in the two rows ⇒

minimum distance to the edge of the pile = 0.2m ⇒ B = 2⋅ 0.2 + 0.25 + 2.20 = 2.55m

♥
here because of the descending nature of the pile diameter a lesser value can be taken , say 2.20m