Pile Design and Construction Practice, Fifth edition

A notable example of precast concrete piling for bridge works is the over-water sections of
the 25 km causeway between Saudi Arabia and Bahrain Island.(9.32)The bridge sections of the
causeway form a total length of 12.5 km and were constructed in water depths ranging from
5 to 12 m. A single 3.50 m OD0.35 m wall thickness precast concrete cylinder supports
the 50 m span box girder carrying the two-lane carriageway of the dual carriageway bridge
(Figure 9.22). The cylinders were cast vertically in short sections at the shore-based casting
yard. The sections were then formed into complete piles by longitudinal prestressing and
transported to the bridge locations by a 1000 tonne crane barge. The crane lifted the piles into
the guides of the twin drilling rigs mounted on a jack-up platform (Figure 9.23). Reverse-
circulation drilling using a Wirth rotary table was used to take the piles down to the required
penetration below sea bed where the base was plugged with concrete.
The foundations for the cable-stayed Sutong Bridge(9.33)over the lower Yangtze River had
to deal with water depths of 30 m with maximum flow rates of 3 m/s and layers of silty sands
and silty clays extending up to 270 m below river level to bedrock. Drilled shafts 131No
2.8/2.5 m diameter, with ultimate capacity of 92 MN, support the two main pylon piers
constructed on a 13 m deep pile cap. Construction of the shafts was carried out from a steel
platform fixed over the pier 3 m above high water, and the 2.8 m casings driven by vibratory
hammers at the north pier and diesel hammer at the south pier to depths of around 60 m. Eight
rotary drills, using a variety of soft formation drill tools 2.5 m diameter, were used on each

464 Miscellaneous piling problems

Figure 9.22Cylinder pile foundations for the Saudi Arabia–Bahrain Causeway (after Beestra et al.(9.32)
Courtesy of Ballast Nedam).

• 7.605

0.000

Variable

Variable

Variable

Weak rock

Sand layers

13.10

Boxgirder

Elastomeric bearing

Pierhead

Precast concrete impact

plug

Scour protection

13.12

Grout

Bottom plug

(concrete cast under water)

min 7.03.0

0.35 2.80 0.35