108 Piling equipment and methods
drives respectively; maximum depth with mechanical drive is 102 m at 2500 mm diameter
using maximum torque of 226 kNm. Soilmec truck-mounted rigs produce 100 kNm torque
for drilling to 43 m at 1800 mm diameter.
Bauer has developed a powerful bucket auger unit (the ‘Flydrill System’) which integrates
the hydraulic power packs and the rotary drive on one platform for mounting on top of a
partially driven tubular pile. The rotary drive produces a torque of 462 kNm at 320 bar and
two hydraulic crowd cylinders provide a pulldown of 40 tonne. The clamping device can
exert a total force of 90 tonne to resist the torque and apply the pulldown. The system oper-
ates a triple telescope kelly with 3 and 4.4 m diameter buckets and was used for cleaning out
and reaming below 4.75 m diameter tubular monopile foundations to allow driving to be
completed to a depth of 61 m at the offshore wind farm in the Irish Sea off Barrow in
Furness (Figure 3.27).
The range and capabilities of crawler-mounted hydraulic rotary piling rigs have increased
significantly in recent years. The rigs in Table 3.6 are usually capable of installing CFA and
rotary displacement piles as well as standard bored piles, but the height of the mast and
stroke available may limit the depth achievable, hence the major manufacturers produce
special long stroke rigs for CFApiles up to 34 m deep. For bored piles many rigs can accom-
modate casing oscillators and most have rams or winches to provide additional crowd and
extraction forces, requiring robust masts and extendable tracks for stability. The major
manufacturers produce double rotary heads (usually capable of rotating in opposite direc-
tions) as attachments for the more powerful piling rigs which enable casing up to 1000 mm
diameter to be installed with the lower drive while augering with the top drive. The
dual-rotary system from Foremost Industries of Canada operating on their DR 40 crawler
Figure 3.26Watson 2100 truck-mounted auger drill.