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p 54
Chapter 2
Helical Foundation Systems
CHAPTER 2
HELICAL FOUNDATION SYSTEMS
2.12.3.2 Retro-Fit Helical Piers
Excavation:
• Hand or machine-excavate to expose the
bottom of the footing. Individual holes should
be approximately 3 feet square while a
continuous trench excavation should extend
at least 3 feet away from the structure.
• Depth of excavation should locally extend 13
inches below bottom of footing and 9 inches
back under bottom of footing where brackets
will be placed
(Figure 2.12.3.2.a)
.
Follow OSHA Trench Safety Procedures.
Failure to follow trench safety procedures
could result in death or serious injury.
Preparation of Footing:
• Notch spread footings 16 to 22 inches wide
(depending upon width of retrofit bracket)
and approximately flush with the face of the
foundation wall
(Figure 2.12.3.2.b)
. Thick
column footings or trench footings often
do not require notching of the concrete,
but should still be prepared so the face of
the footing has full contact with the back,
vertical plate of the bracket.
• Clean and prepare bottom of footing to allow
full contact and seating of the bracket.
Installation of Helical Pier:
• Attach lead section to drive head and
product adaptor.
• Place lead section’s first blade under the footing
and the shaft of the lead 1½ inches away from
bottom edge of footing
(Figure 2.12.3.2.c)
. This
will allow alignment of the lead to the required
angle of inclination of 3.0 ± 1.0 degrees from
vertical. As additional plates on the lead
section advance down the face of the footing
and pass the bottom of the footing, forward
crowd will be required to realign the shaft to the
appropriate inclination. In the case of a vertical
pile installation, a pilot hole is required to set
all plates of the lead below the bottom of the
footing before advancement of the pile. The
pile shaft is still set 1½ inches from the face of
the footing.
Figure 2.12.3.2.b
Footing preparation
Figure 2.12.3.2.c
Alignment of lead
Figure 2.12.3.2.a
Excavation at bracket