Pile Design and Construction Practice, Fifth edition

Pile groups under compressive loading 297

From Figure 5.44,

Iz

Layer For L/B 1 For L/B 10

1 0.20 0.24

2 0.36 0.30

3a 0.46

3b 0.40

0.39

Layer For L/B 1 Ed For L/B 10

15 2.5 12.5 MN/m^25 3.5 17.5 MN/m^2

216 2.5 40 MN/m^216 3.5 56 MN/m^2

320 2.5 50 MN/m^220 3.5 70 MN/m^2

For axisymmetric loading (L/B1) from equation 5.35:
Uncorrected settlement is given by:

Layer 1 278 0.20^6 ^1000

12.5 1000

27 mm

Soft clay

Sand

Ground level

Pile group

0

B/2 5 11.2 m

Base of equivalent raft

35.4 3 27.4 m

0 0.1 0.2 0.3 0.4 0.5 0.6

Rock

0

0510

Cone resistance, MN/m^2

15 20 25

5

10

15

Depth, metres

20

25

28

30

35

40

45

46

Layer 1 (av. 5 MN/m^2 )

Layer 2 (av. 16 MN/m^2 )

Layer 3 (av. 20 MN/m^2 )

22

33.2

Figure 5.44