Pile Design and Construction Practice, Fifth edition

42 Types of pile

The pile was then cleaned out and plugged with concrete but failed under a test load of
6300 kN.
It was evident from the driving records that the plain piles showed little evidence of
developing base resistance by plugging and would have had to be driven much deeper
to obtain the required bearing capacity. In order to save the cost and time of welding-on
additional lengths of pile it was decided to provide end enlargements in the form of six
0.4510.3037.0 m long T-sections welded to the outer periphery in the pattern
shown in Figure 2.19b. The marked increase in driving resistance of the trial pile
is shown in Figure 2.20. The final resistance was approaching refusal at 194
blows/200 mm at 19 m below sea bed. The winged pile did not fail under the test load
of 6300 kN.
A disadvantage of the H-pile is a tendency to bend about its weak axis during driving. The
curvature may be sharp enough to cause failure of the pile in bending. Bjerrum(2.9)recom-
mended that any H-pile having a radius of curvature of less than 366 m after driving should

Driving resistance (blows/200 mm)

1 067 mm OD × 32 mm wall thickness

(50 mm at shoe) open-end steel

tube

1 067 mm OD as TP3 but with

6 no. 0.451 × 0.303 × 7.0 m long

T-sections welded to outer

periphery at toe

TP3 –

TP4 –

500 100 150 200

Sea bed

Loose very silty

fine sand

(N 5 2 to 11)

6.5

22.6

160 blows/200 mm

Second re-drive

Depth below sea bed (m)

First re-drive

TP4

TP3

25

20

15

10

5

39 blows/200 mm

Piles driven by Menck MRB 1000 single – acting hammer (10 tonne ram, 1.25 m drop)

194 blows/200 mm

Dense slightly silty

fine sand with

gravel and cobbles

(N 5 50)

N denotes standard

penetration resistance

in blows/300 mm

Figure 2.20Comparison of driving resistance of open-end plain and winged tubular steel piles at
Britoil Tanker Terminal, Cromarty Firth.