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6.5 Pile inclinations
Raking piles can be used to increase the stability of the
pile foundation as desired. However, stresses on the
raking piles from possible deformations of soil layers must
be taken into account.
The maximum deviation in pile positions from the vertical,
or limit inclination, depends on used piling equipment and
the structure of soil layers at the foundation. When RR piles
are installed with equipment used also in precast concrete
piling, or RD piles are installed with heavy piling equipment,
both forward or backward tilting piles of this type may
usually be installed to a maximum inclination of 3.5:1. With
large diameter piles, especially (the mast) tilted forward, the
maximum allowed inclination must be determined on the
basis of the stability of the basic equipment, considering used
pile length and bearing capacity of the subsoil separately in
each case. When installing piles with light or medium-heavy
equipment, small diameter RR and RD piles can be installed
at a highly inclined angle, even horizontally, if the structure
and stability of the installation equipment allow it. High
inclinations usually require using short pile sections.
It is worthwhile looking into the properties of the
installation equipment at the design stage, if the aim is to
install piles at exceptional inclinations.
6.6. Allowed positional and angular deviations
Piles should be installed exactly in the planned position and
at the planned angle. However, a pile must not be forced into
its theoretical position during installation or thereafter.
The measurement accuracy of pile position before and after
installation is 0.01 m, unless otherwise specified in the designs.
Unless otherwise required by structural requirements,
detailed instructions on structures by the authorities, soil
conditions, used piling equipment or a very deep cutting
level, the following allowed positional deviations are used:
Small diameter RR, CSG-RR and RD piles
(RR75– RR/RD320):
•
individual vertical or raking pile, pile slab or bearing
plate structure:
e
≤
e
max
= 0.10 m
•
individual pile in a small pile group (4 to 8 piles):
e
≤
e
max
= 0.15 m, individual pile in a larger pile group: e
≤
e
max
= 0.2 m, however, for the centre of gravity of the
entire group
e
≤
e
max
= 0,05 m
•
in pile foundations used in building construction
e
≤
e
max
= 0.15 m, in particularly exacting conditions,
such as areas of pre-penetratable fills, relief drilling,
etc.,
e
≤
e
max
= 0.20 m
•
for an individual pile in a pile row,
e
≤
e
max
= 0.15 m,
however, for the centre of gravity of the entire row
e
≤
e
max
= 0.05 m in the direction perpendicular to the
row (a pile row is defined as piles under an elongated
pile footing when there is only a single pile in the cross
direction of footing)
•
for individual vertical or raking piles
i
≤
i
max
= 0.04
(0.04 m/m) in a group of parallel piles
i
≤
i
max
= 0.02
(0.02 m/m)
•
the horizontal direction (horizontal projection) of inclined
piles may differ at most 10° from the design direction.
At underpinning sites it is often necessary to use clearly
deviating values.
Large diameter RR and RD piles
(RR/RD400 to RR/RD1200):
•
vertical and raking piles: horizontal position measured
from the working level:
e
≤
e
max
= 0.10 m RR/RD400–RR/RD1000
e
≤
e
max
= 0.12 m RR/RD1200
•
vertical and raking piles at an angle of
n
≥
15 (
Q ≥
86°):
angular deviation
i
≤
i
max
= 0.02 (0.02 m/m)
•
raking piles at an angle of 4
≤
n
< 15 (76°
≤ Q
< 86°):
angular deviation
i
≤
i
max
= 0.04 (0.04 m/m)
RD piles, especially when using the concentric drilling
method, easily achieve tolerances stricter than the above
ones. Stricter tolerances are recommended for RD piles if
stricter building tolerances are called for by the structure
and loads, and the soil and installation conditions allow
them. The attainment of stricter tolerances requires
special care in both the in-place measurement and
installation work.
From the viewpoint of the installation work, however,
it is not advisable without justification to apply stricter
tolerances to RD piles than those presented below:
•
vertical and raking piles: horizontal position measured
from the working level:
e
≤
e
max
= 0.025 m
•
vertical or raking piles at an angle of
n
≥
15 (
Q ≥
86°)
angular deviation:
i
≤
i
max
= 0.015 (0.015 m/m)
•
raking piles at an angle of 4
≤
n
< 15 (76°
≤ Q
< 86°)
angular deviation:
i
≤
i
max
= 0.025 (0.025 m/m)