Helical Piles Installed for Culver's Restaurant in Orland Park, IL

Challenge

Construction details for the new Culver’s restaurant included an 8-inch-thickpoured concrete foundation wall, steel framing and anchored masonryveneer. Based upon the geotechnical investigation, project engineersrecommended helical piles be used to support the structure. Four testborings extended to depths of 25 feet and encountered stiff silty clay at thebottoms of each of the borings. In fact, all four test borings identifiedconsistent soil types, strengths, layer thicknesses and strata depths.Existing fill soil was encountered from the surface to a depth of 11 feet,over soft peat from 11 to 15 feet, over loose organic silt from 15 to 19 feet.Therefore, the helical piles were designed to extend beyond the 19-footdepth for bearing in stiff silty clay.

Solution

Due to scheduling issues and forecasted cold weather conditions, pouringconcrete at the site needed to be completed within 13 days from the start ofconstruction. Helical piles became an even more logical solution sincefoundation concrete can be poured immediately after installation of thepiles. Forty-seven (47) Foundation Supportworks Model 288 Helical Pileswere specified on the project with allowable capacities of 5, 10, 15, 20 and25 kips. Three different helical lead configurations were installed to torquevalues that correlated to the respective capacities, or higher, including afactor of safety of two. Isolated obstructions were encountered within thefill at depths between 10 and 12 feet, but the piles were able to advancethrough or around this material. Large boulders were also encounteredwithin the first few feet at several locations, requiring removal in order tocomplete the pile installation. Despite the challenges, the installation of the47 helical piles was completed in less than three days and the projectremained on schedule.

Project Summary

Architect: Warren Johnson Architects, Inc

Structural Engineer: Virgilio & Associates

Geotechnical Engineer: Construction Testing Services

Certified Installer: Foundation Supportworks of WI

Products Installed: (47) Foundation Supportworks Model 288Helical Piles