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Case Study: Combo Helical Piles & Helical Pulldown Micropiles


Underpinning & New Construction Helical Piles


Helical Pile Installation Contractor: Certified Foundations, Inc. – Lakeland, FL
General Contractor: NuJak Development, Inc. – Lakeland, FL
Geotechnical Engineer: Madrid Engineering – Bartow, FL

Helical Specifications:  (22) SS5 Sq. Bar Leads with 10”-12”-14” Helicies Followed by 2.875” Round Shaft Extensions; (15) SS200 2.0” RCS with 8”-10”-12”- 14” Helicies; 5” to 7” Grout Column; Capacities Ranged from 10-80 KIPS Allowable


Combo Helical Piles & Helical Pulldown Micropiles


 Before excavation could begin for a new five story building, an adjacent two story building needed to be underpinned to prevent any foundation failure from the excavation for the new building.


Needed to support the current 2 story building, provide soil supports for the excavation of the existing foundation with chemical grouts. The bottom of the new foundation was to be 8’ below the existing foundation. Install a pile supported foundation to support a 227 kip 5 story tilt panel wall with the existing foundation piles passing through it. Isolate the piles to not allow transfer or settlement to affect either of the pile designs for the existing or new foundation system.


(20) Chance helical piles were installed as deep foundations for the new five story building. The assortment of piles included:

(10) SS200 Helical Pulldown Micropiles – 80 kip allowable compression loads – with 5”-7” grout columns

(5) SS200 Helical Pulldown Micropiles – 35 kip allowable compression loads – with 5”-7” grout columns

(5) SS5 Leads followed by 2.875” Round Shaft Combo Piles – 20 kip allowable tension loads