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Helical Pile Design Verification - Pipe Section Pile

RS2875.165 (2.875 in Pipe Section) with 8''-10''-12'' Helixes

A. Project description

This example presents a detailed example for calculating the ultimate axial capacity of a helical pile according to Vesic 1974 and Meyerhoff/Hansen method. Table 1 below presents assumed soil properties, Table 2 summarizes the soil stratigraphy, while Table 3 describes assumed helical pile properties.

Table 1: Soil properties

Table 2: Stratigraphy (Boreholes)

Table 3: Helical pile properties

Soil Properties and Model in HelixPile

Pile Section Properties and Helix Configuration

B. Ultimate bearing capacity calculations – Cylinder failure method

B1. Manual calculations

For the cylinder lateral pressures factor, we will use the Mitch – Clemence method:

K = 0.09e(0.08fr) = 0.09

Table 4:  Ultimate shear stress line force calculations.

Figure: Ultimate shear stress line force on cylinder body.

Cylinder strength: Fcylinder = A1 + A2 = 14375 + 9420 = 23795 lbs = 23.8 kips

Vesic method

Tip: Fult = 0.86 kips (compression)

Plate 1: Fult = 5.85 kips (compression)

Plate 3: Fult = 13.89 kips (tension)

So, the utimate cylinder compression capacity is Fult, comp =  23.8 + 0.86 + 5.85= 30.51 kips

The utimate cylinder tension capacity is Fult, tension =  23.8 + 13.89 = 37.69 kips

Meyerhoff/Hansen

Tip: Fult = 0.81 kips

Plate 1: Fult = 5.58 kips

Plate 3: Fult = 13.32 kips

So, the utimate cylinder compression capacity is Fult, comp =  23.8 + 0.81 + 5.58 = 30.19 kips

The utimate cylinder tension capacity is Fult, tension =  23.8 + 13.32 = 37.12 kips

B2. Calculations with HelixPile

The following images present the calculated compression and tension cylinder capacities with the Vesic and Meyerhoff/Hansen methods respectively. The analysis has been performed with HelixPile software.

Figure: Cylinder Capacities in HelixPile - Vesic Method

Figure: Cylinder Capacities in HelixPile - Meyerhoff/Hansen Method

Table 5:  Comparison between manual calculations and HelixPile results.

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