ToolFusion
πŸ“‹ Case Study

Great Lakes Winter Site Foundation Uplift Due to Snow-Wind Synergy

Helical pile uplift during January 2023 blizzard event: 14% of rows experienced >3Β° rotation

πŸ—οΈ Project Overview

120MW tracker farm in Michigan with 85 psf ground snow load and frequent 70 mph gusts

🎯 Challenge

Helical pile uplift during January 2023 blizzard event: 14% of rows experienced >3Β° rotation

πŸ”§ Design Approach

Replaced standard helixes with dual-helix anchors; implemented ASCE 7-22 Load Combo 4 (1.0D + 0.75W + 1.5S) as design basis; added soil-concrete grout collar

πŸ“ Design Diagram

Great Lakes Winter Site Foundation UpliftSoil surfaceDual-Helix AnchorUpper Helix (d=24")Lower Helix (d=36")Pile ShaftConcrete-Soil Grout Collar (L=48", d=22")+4.3 kips bond uplift resistanceF_up = 18.2 kips/row(ASCE 7-22 LC4)Soil-grout interfaceHelical pile (replaced)Standard helix (old)Design: Dual-helix + grout collar | Uplift reduction: 23.6% vs. baselineRotation mitigation: <1Β° (vs. 3Β°+ observed)

AI-generated project design illustration

πŸ“ Key Calculations

Combined Uplift Force

F_up = A Γ— (p_wind + p_snow Γ— sinΞΈ)
Result: 18.2 kips/row
Exceeded original anchor capacity by 27%

Grout Bond Contribution

Ο„_bond Γ— Ο€ Γ— d Γ— L
Result: +4.3 kips
Restored safety margin to 1.4Γ—

πŸ“Š Results

Zero uplift events in subsequent 2 winters; 100% retention mb-3 flex items-center gap-2">πŸ’‘ Lessons Learned
  • β€’Snow load directionality matters β€” lateral snow pressure adds to wind-induced overturning
  • β€’Grout collar depth must exceed frost line by β‰₯24 inches in USDA Zone 5

βœ… Key Takeaways

  • 1Snow load directionality matters β€” lateral snow pressure adds to wind-induced overturning
  • 2Grout collar depth must exceed frost line by β‰₯24 inches in USDA Zone 5