WOH blow counts to 40′ called for a deep foundation. An 8 5/8″ pipe pile could handle the load for the multi-story apartment building and deal with potential buckling and lateral concerns, but was cost prohibitive. Danbro suggested an uncased Grouted Helical Micropile, which could achieve the load with added skin friction from the uneven grout column, at a lower cost, and still overcome design issues and site concerns.
Project Summary:
- Helical Pile Type: IDEAL 3 1/2″ pipe pile with a 10″ uncased grout column
- # of Helical Piles: 1 test pile
- Installation Depth: 45′-50′
- Ultimate Pile Capacity: 80 Kips
- Equipment Used: Hitachi U w/ 20,000 Ft. Lb Drivehead
- Challenge/Unique Aspect: The IDEAL Group provided a special order 3.5″ pipe pile with 10″ displacement plates welded to the lead section and extensions. This accommodation contributed to increased productivity and would greatly contribute to the economics for the foundation on this project. The pile was tested to 80 kips (required capacity), 100, and 120 kips without any significant deflection. The capacity derived from the grout column comes at a significantly lower “cost per kip” than associated with the 8 5/8″ pipe pile originally considered.
