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Pile Design and Construction Practice, Fifth edition

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(a) (b) (c)<br />

No load<br />

on pile<br />

Residual value of negative<br />

skin friction<br />

Peak value of negative<br />

skin friction<br />

Negative skin<br />

friction reducing<br />

<strong>Pile</strong> moves down<br />

relative to fill<br />

causing fill to<br />

act in support<br />

of pile<br />

Depth of penetration (m)<br />

0<br />

10<br />

20<br />

30<br />

40<br />

50<br />

60<br />

0 0.1 0.2 0.3<br />

<strong>Pile</strong> compresses elastically<br />

relative to fill <strong>and</strong><br />

negative skin friction<br />

is eliminated<br />

Residual<br />

value<br />

Peak value<br />

Reduces<br />

to zero<br />

Compressible<br />

bearing stratum<br />

Yielding of pile due<br />

to dragdown load<br />

Skin friction factor, b<br />

W<br />

0.4 0.5 0.6<br />

Figure 4.39 Negative skin friction factors for piles driven into soft to firm clays (after Meyerhof (4.37) ).<br />

Original surface of fill<br />

W<br />

Fill settling<br />

under<br />

own<br />

weight<br />

H<br />

Yielding of pile<br />

under combined<br />

dragdown load<br />

<strong>and</strong> applied load W<br />

Residual<br />

Peak<br />

0.IH<br />

Length of shaft over<br />

which calculated<br />

yielding of pile toe<br />

exceeds settlement<br />

of fill<br />

Figure 4.40 Distribution of negative skin friction on piles terminated in compressible stratum (a) No<br />

load on pile head (b) Compressive load on pile head (c) <strong>Design</strong> curve for loaded pile.

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