Geotechnical Data and Pile Design - Offshore Structures: Design, Construction and Maintenance - page 250

1.2

1

0.8

0.6

0.4

0.2

0

0 0.02 0.04 0.06

z / D

0.08 0.1 0.12

FIGURE 4.6 Pile-tip load displacement (Q-z) curve.

TABLE 4.12 Relation between the Axial Deflection to Pile Diameter Ratio

and Percentage of End-Bearing Capacity

z/D Pile Axial Deflection for Different Pile Diameters,

mm

Q/Q p

24″ 36″ 48″

0.002 1.2 1.8 2.4 0.25

0.013 7.9 11.9 15.8 0.50

0.042 25.6 38.4 51.2 0.75

0.073 44.5 66.8 89 0.90

0.100 61 91.4 121.9 1.00

z = axial tip deflection (in mm), D = pile diameter (in mm), Q = mobilized end-bearing capacity (in lb
or KN) and Q p = total end bearing (in lb or KN).

Axial Pile Capacity
A number of studies were performed that were aimed at collecting and compar-
ing axial capacities from relevant pile load tests to those predicted by traditional
offshore pile design procedures. Studies like these can be very useful in temper-
ing one s judgment in the design process. It is clear, for example, that there is

considerable scatter in the various plots of measured versus predicted capacities.

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