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Soil Nailing
Soil nailing is a
stabilization method of reinforcing existing soil by
installing threaded steel bars into slopes or cuts as
construction proceeds from top down. Grouted bars
are installed to create a stable mass of soil, first step in building a
solid wall.
The nailing process
creates a single block of earth able
to hold-back its overburden. Soil nailing
is an economical means of creating shoring systems and
retaining walls. Often, nailing is less disruptive
than other means of constructing retaining systems.
Soil nailing not only works in tension,
but also bending and shearing forces. Generally, this
process increases bonding strength of media
through its ability to carry tensile loads. A constructed
face is usually required over shoring bars, typically made of
a shotcrete cover,
which is reinforced using woven mesh over steel plates. Permanent walls
are usually built with a cast-in-place face over
the wall surface.
Soil Nailing Advantages:
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Used to follow irregular curves.
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Equipment is portable for
tight
spaces.
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The technique is flexible,
easily
modified.
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Creates less noise and traffic
obstructions.
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Less impact on nearby properties.
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Requires
minimum
shoring space.
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Installation Sequence
The shoring requires drilling through
the active zone into
ground's passive zone.
1. A five foot cut is made to begin initial level of
the nailing operation.
2. Holes are drilled into cut bank on about five foot centers.
3. Threaded bars are placed in shoring holes.
4. Threaded bars are grouted in place from bottom up.
5. Wire screen attached to rebar reinforcement installed over
cut
face.
6. First coating of shotcrete applied to cover protruding
threaded bar.
7. Plates, washers, nuts positioned on shoring bars then
locked down.
8. Second coat of shotcrete applied over soil and plates.
9. Repeat steps 1 through 8 for every lift of retaining wall
construction.
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