Pile Design and Construction Practice, Fifth edition

and the tower is subject to a maximum horizontal wind force of 1 500 kN with a centre of
pressure 35 m above ground level. The base of the tower is 12 m in diameter. Design the
foundations and estimate the settlements under the dead load and wind loading.
Because of the presence of the soft clay layer, piled foundations are required and the
heavy vertical load favours the use of large bored and cast in-situ piles. A suitable arrange-
ment of piles to withstand the eccentric loading caused by the wind force is 22 piles in the
staggered pattern shown in Figure 6.46.

368 Piles to resist uplift and lateral loading

Base of equivalent

block foundation for

N–S wind direction

W

S

Base of equivalent

block foundation

for E–W wind direction

Very soft

clay

35.00

1500 kN

30 000

kN

Base of tower

6.00

7.70

Base of tower

E

3.00 3.00 3.00

3.00 3.00 3.00 3.00

N

Resultant

Very stiff clay

(Cu 5 190 kN/m^2

Ed= 80 MN/m^2

mv= 0.05 m^2 /kN)

e 5 2.43

e 5 1.75

Figure 6.46