Performance-Based Design for Helical Piles

Abstract

Performance of a deep foundation under applied loading dictates the design. In all circumstances, performance is considered poor if significant settlement or deflection occurs. Although the physics around helical pile performance may be quite simple, it is often the most overlooked factor by practicing engineers using the current helical pile design methods. This paper shows the importance of understanding critical-state soils mechanics when designing helical piles and includes a case study, where a helical pile was installed in dense sand for which high energy torque was required for installation. Load tests from that test show affiliated dilation, and, ultimately, the helical piles poor-performance when evaluated under uplift loading. Finite element modeling is included that further validate these findings.