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Chapter 2
Helical Foundation Systems
CHAPTER 2
HELICAL FOUNDATION SYSTEMS
2.10 Load Tests
Load tests are routinely completed on helical
piles to establish ultimate and allowable pile
capacities, determine pile head movement
under load, verify design assumptions and
capacities, and establish site-specific torque
correlation factors (K
t
). ICC-ES AC358 states
that full-scale load tests on helical piles shall
be conducted in general accordance with the
following standards:
• ASTM D1143, Standard Test Methods for Deep
Foundations Under Static Axial Compressive
Load
(Figures 2.10.a1 and 2.10.a2)
• ASTM D3689, Standard Test Methods for
Deep Foundations Under Static Axial Tensile
Load
(Figures 2.10.b1 and 2.10.b2)
• ASTM D3966, Standard Test Methods for
Deep Foundations Under Lateral Load
AC358 further states that the Quick Test method
of ASTM D1143 shall be used for compression
tests. Additional discussion and guidance
regarding the test procedures are provided in
AC358 and within the respective standards.
For axial compression and tension tests, AC358
defines the ultimate pile capacity as the load
achieved when plunging of the helix plate occurs
or when the net deflection exceeds 10 percent
of the average helix diameter, whichever occurs
first. Net deflection is defined as the total pile
head deflection minus the elastic shortening or
lengthening of the shaft.
Figure 2.10.a1
Compression load test
Figure 2.10.b1
Tension load test
Figure 2.10.b2
Tension load test within basement
Figure 2.10.a2
Close up of test pile, hydraulic cylinder,
dial gauges and hemispherical bearing plate
