Liebherr LRB 125 XL - Manual (Page 2)

2
Vibrated cast-in-place pile
Description
Vibrated cast-in-place piles are installed in the shielding
of an outer casing. The casing, which is closed at its
bottom end with a base plate, is vibrated down to
the required depth using a high frequency vibrator.
The base plate is disposable and can be fitted with a
sealing to prevent groundwater ingress. Once the final
depth has been reached, a reinforcement cage can
be inserted into the casing. Subsequently concrete
is poured in from the top and the casing is extracted
with the help of the high frequency vibrator. Due
to the vibration, the fresh concrete is compacted.
Furthermore, the concrete interlocks with the
surrounding soil and the finished pile offers high skin
friction and thus high load-bearing capacity.
Applications
Depending on the soil conditions it may be useful to
install a geotextile hose into which the reinforcement
is inserted. On the one hand, this prevents the liquid
concrete from penetrating soft soil types. On the other
hand, pile necking due to caving in of soil is avoided.
When installing vibrated cast-in-place piles – as when
vibrating other pile types – it is possible to apply jetting
as an installation aid. In this case jet pipes are welded
onto the casing to be vibrated. During the vibration
process water, air or a combination of both are pumped
through these pipes in order to reduce the skin friction
during installation of the casing.
The vibrated cast-in-place pile process is used for the
installation of foundation piles, sealing piles and pile
walls (tangential and intermittent).
A special variation is the production of sand piles and
gravel piles.
Soil types
The vibrated cast-in-place pile process is suitable for
non-cohesive soils (sand, sand/gravel mixtures) – even
densely layered. In cohesive soils (silt, clay) it can be
applied up to stiff consistency.
Advantages
• High performance as the casing is rapidly inserted in one
piece.
• Since the base plate is sealed the concrete can be poured
into the dry casing from the top.
• High load-bearing capacities of the finished piles.
• The dimensions of the piles can be controlled through the
use of geotextile hoses.
• As the soil is displaced at the pile base the load-bearing
capacity of the surrounding soil is increased.
• Thanks to the use of high frequency vibrators with variable
static moment no vibrations are emitted that could cause
damage to adjacent buildings.
• Low noise level.