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APPENDIX 2F
MODEL SPECIFICATIONS
Chapter 2
Helical Foundation Systems
3.1.12 Helix (Helical) Plate: Generally round steel plate formed into a helical spiral and welded
to the central steel shaft. When rotated in the ground, the helix shape provides thrust
along the soil nail’s longitudinal axis thus aiding in soil nail installation. The plate transfers
axial load to the soil through bearing.
3.1.13 Helix Pitch: The distance measured along the axis of the shaft between the leading and
trailing edges of the helix plate.
3.1.14 Lead Section: The first helical soil nail shaft component installed into the soil. It consists
of multiple helical plates welded to a central steel shaft.
3.1.15 Limit State: A condition beyond which a helical soil nail component or interface
becomes unfit for service and is judged to no longer be useful for its intended function
(serviceability limit state) or to be unsafe (ultimate limit state (strength)).
3.1.16 Load and Resistance Factor Design: A structural and geotechnical design methodology
that states that the Factored Resistance (Design Strength) must be greater than or equal
to the summation of the applied factored loads.
3.1.17 Load Factor: A factor that accounts for the probability of deviation of the actual load
from the predicted nominal load due to variability of material properties, workmanship,
type of failure and uncertainty in the prediction of the load (Load and Resistance Factor
Design).
3.1.18 Load Test: A process to test the ultimate soil nail capacity and relation of applied load
to soil nail head movement by application of a known load on the helical soil nail head
and monitoring movement over a specific time period.
3.1.19 Loads: Forces that result from the weight of all building materials, occupants and their
possessions, environmental effects, differential movement, and restrained dimensional
changes. Permanent loads are those loads in which variations over time are rare or of
small magnitude. All other loads are variable loads (see also Nominal Load).
3.1.20 Mechanical Strength: The maximum load or the load at a specified limit state that can
be resisted by the structural elements of a helical soil nail.
3.1.21 Net Deflection: The total deflection at the helical soil nail head minus the theoretical
elastic deformation of the soil nail shaft during a load test.
3.1.22 Nominal Loads: The magnitude of the loads specified, which include dead, live, soil,
wind, snow, rain, flood and earthquakes (also referred to as service loads or working
loads).
3.1.23 Nominal Resistance: The soil nail capacity at a specified ultimate limit state (Load and
Resistance Factor Design). See Ultimate Soil Nail Capacity.
3.1.24 Nominal Strength: A term used in structural design which is defined as the structure or
member capacity at a specified strength limit state. See Ultimate Soil Nail Capacity.
3.1.25 Resistance Factor: A factor that accounts for the probability of deviation of the actual
resistance (strength) from the predicted nominal resistance (strength) due to variability
of material properties, workmanship, type of failure and uncertainties in the analysis
(Load and Resistance Factor Design).