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Pile Design and Construction Practice, Fifth edition

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470 Miscellaneous piling problems<br />

<strong>Pile</strong> cap<br />

Pier<br />

Riverflow (tidal)<br />

(a) (b)<br />

Sheet piles<br />

High water<br />

Low water<br />

River bed<br />

Impervious<br />

stratum forming<br />

cut-off for sheet piles<br />

Precast concrete box<br />

Rubber seal<br />

to opening<br />

1800 mm OD tubular<br />

steel piles supporting<br />

fender beam<br />

Trough-section<br />

RC fender beam<br />

1500 mm OD<br />

tubular steel<br />

piles<br />

<strong>Pile</strong> cap supporting<br />

bridge pier<br />

Figure 9.27 Fender beam <strong>and</strong> piles protecting the river piers of the Sungei Perak Bridge, Malaysia<br />

(after Stanley (9.36) ).<br />

Figure 9.28 <strong>Construction</strong> of submerged pile caps (a) In cofferdam (b) In open-topped box.<br />

conditions where a sufficient period of time is available for the concrete to set before the<br />

bottom of the box is submerged. Arrangements should be made to flood the box to equalize<br />

pressures above <strong>and</strong> below the seal until the concrete has hardened (Figure 9.28b).<br />

Where piers are located in deep water <strong>and</strong> there is a risk of ship collision it is desirable to<br />

construct the pile cap at bed level in order to eliminate any unsupported length of piling.<br />

This arrangement is also desirable if lateral forces from earthquakes are transmitted from<br />

the bridge superstructure <strong>and</strong> piers on to the piles. The pier <strong>and</strong> pile cap can be constructed<br />

Pier<br />

Concrete infill<br />

High water<br />

Collar<br />

Low water<br />

River bed

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