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p 57
Chapter 2
Helical Foundation Systems
CHAPTER 2
HELICAL FOUNDATION SYSTEMS
2.12.3.3 Helical Tiebacks
Helical tiebacks can be installed using either
machine-mounted or hand-held drive heads. Basic
installation procedures consist of the following:
• Attach lead section to product adaptor and
install hitch pin or bolt.
• Elevate lead section along with drive head
assembly and place tip of tieback at marked
location.
• Establish angle of inclination and align lead
section per design specifications.
• Provide minimal crowd to seat lead shaft tip.
• Install lead section while maintaining
installation angle.
• Connect extension section to the lead and
tighten bolted connection at coupler.
• Continue adding extensions until embedment
length and minimal torque requirements are
met.
Refer to the Model Specifications for
Helical Anchor Foundations in Appendix 2F
for termination criteria when the minimum
overall length or minimum torsional
resistance is not met.
• Remove installation equipment and install
threaded transition assembly on end of
extension. Tighten coupling bolt.
• Install threaded rod into transition so threads
are fully engaged.
• Place wall plate, bracket or waler system over
threaded rod. Place nut on threaded rod and
tighten to bearing plate.
• Tighten nut to a predetermined torque to
correlate to an axial tensile force. For larger
projects, a calibrated hydraulic cylinder may
be used to pre-tension the tieback to the
design working load or to run a load test.
• Remove equipment and cut threaded rod.