Pile Design and Construction Practice, Fifth edition

Measurements made in the centrifuge model of pile head deflections, bending moments,
and deduced horizontal soil pressures on the surfaces of the central pile of the three-pile row
furthest from the embankment are shown in Figure 9.18. They show a marked difference in
the magnitude of deflection and pressure between the short-term (end of construction) and
long-term (125 weeks after end of construction) loading periods. The pressure on the pile
surface within the soft clay was negative at the end of construction as a result of the large
deflections causing the pile to pull away from the soil. With time the clay closed-up against the

Miscellaneous piling problems 459

Figure 9.18Lateral pressure distribution on full height bridge abutment supported by two rows
of piles driven through soft clay into dense sand (a) deflection (b) bending moments
(after Springman et al.(9.25)). Crown copyright 1995. Reproduced by permission of HM
Stationery Office.

(b)

(a)

5.0

0

10.0

15.0

• 10 – 55
  Bending moment (MN/m)

Depth below soft clay surface (m)

01015

20.0

5.0

• 100 0
  Pressure

Pressure

Abutment wall

Fill

8.0 m

6.0 m

5.0 m

1.0 m dia RC piles

13.0 m

GL

Soft

clay

Dense

sand

Long term

Short term

Key

Drainage

layer

10.0

15.0

• 50 0 100
  Deflection (mm)

Deflection

Deduced pressure (kN/m^2 )

Depth (m)

50 150 200

200100 300 400 500

20.0