STEP 2: Design Results

July 10, 2026

Helical Pile Design Results

Showing 2 design calculation(s) for this boring log.
Design #2
2026-04-09T21:18:45.082748+00:00
ERROR
Design Parameters
Design Load:
20.0 kips
Safety Factor:
2.0
Required Ultimate:
20.00 × 2.0 = 40 kips
Shaft System:
None
Recommended Configuration

Design: Option 1: SS175 Triple Helix 10"-12"-14"

Shaft System: SS175

Ultimate Capacity: 98.34 kips

Allowable Capacity: 49.17 kips

Status: PASS

Capacity Ratio: 2.46

Rationale: This configuration ensures engagement with the strongest soil layers, achieving the required ultimate capacity with redundancy.

Individual Helix Capacities
Helix # Diameter (in) Depth (ft) Area (sq ft) Soil Type Cohesion (ksf) Friction Angle (°) Nq Factor Soil Capacity (kips) Mech. Limit (kips) Ultimate (kips) Controlling
1 10 12.0 0.531 Lean Clay 3.75 0.0 1.50 19.03 100.00 19.03 Soil
2 12 15.5 0.771 Sandy Lean Clay 4.50 0.0 1.50 33.32 100.00 33.32 Soil
3 14 19.0 1.049 Sandy Lean Clay 4.50 0.0 1.50 45.99 80.00 45.99 Soil
Total Ultimate Capacity: 98.34 kips

Calculation Method: Individual Bearing Method (A.B. Chance Design Manual)

All Design Alternatives (3)
# Design Name Shaft System Configuration Ultimate (kips) Allowable (kips) Status Ratio Failure Analysis
1 Option 1: SS175 Triple Helix 10"-12"-14" SS175 10"- 12"- 14" 98.34 49.17 PASS 2.46 -
2 Option 2: SS150 Double Helix 12"-14" SS150 12"- 14" 79.15 39.57 PASS 1.98 -
3 Option 3: SS175 Single Helix 14" SS175 14" 45.62 22.81 PASS 1.14 -
Design #1
2026-01-03T17:24:26.201002+00:00
ERROR
Design Parameters
Design Load:
20.0 kips
Safety Factor:
2.0
Required Ultimate:
20.00 × 2.0 = 40 kips
Shaft System:
None
Recommended Configuration

Design: Option 1: SS175 Triple Helix 10"-12"-14"

Shaft System: SS175

Ultimate Capacity: 102.82 kips

Allowable Capacity: 51.41 kips

Status: PASS

Capacity Ratio: 2.57

Rationale: Meets 40-kip ultimate capacity requirement. Helices engage both silty sand and clay layers. Design controlled by SS175 mechanical limit.

Individual Helix Capacities
Helix # Diameter (in) Depth (ft) Area (sq ft) Soil Type Cohesion (ksf) Friction Angle (°) Nq Factor Soil Capacity (kips) Mech. Limit (kips) Ultimate (kips) Controlling
1 10 15.0 0.531 Sandy Lean Clay 4.50 0.0 1.50 22.90 100.00 22.90 Soil
2 12 18.5 0.771 Sandy Lean Clay 4.50 0.0 1.50 33.74 100.00 33.74 Soil
3 14 22.0 1.049 Sandy Lean Clay 4.50 0.0 1.50 46.18 80.00 46.18 Soil
Total Ultimate Capacity: 102.82 kips

Calculation Method: Individual Bearing Method (A.B. Chance Design Manual)

All Design Alternatives (3)
# Design Name Shaft System Configuration Ultimate (kips) Allowable (kips) Status Ratio Failure Analysis
1 Option 1: SS175 Triple Helix 10"-12"-14" SS175 10"- 12"- 14" 102.82 51.41 PASS 2.57 -
2 Option 2: SS150 Double Helix 12"-14" SS150 12"- 14" 79.15 39.57 PASS 1.98 -
3 Option 3: SS175 Single Helix 14" SS175 14" 46.18 23.09 PASS 1.15 -
Run New Design
Back to Soil Data
Soil Profile Summary
Layer Depth Range (ft) Soil Type SPT N-Value Unit Weight (pcf)
1 0.0 - 5.0 Lean Clay 10 120
2 5.0 - 10.0 Silty Sand 10 110
3 10.0 - 15.0 Lean Clay 10 120
4 15.0 - 20.0 Sandy Lean Clay 10 120
View Full Soil Data