Dynamic Load Testing of Helical Piles-PPT Presentation

PPT Presentation

Pdf Summary

The seminar, presented by Benjamin White, P.E., of GRL Engineers, reviewed dynamic load testing of helical piles, tiebacks, and anchors as a possible alternative to static load testing.<br /><br />Static testing can assess creep and time-dependent settlement, and embedded instrumentation can show load distribution and pile behavior. It can be conducted in compression, tension, or lateral loading. However, it may be expensive and time-consuming, and may not always reveal how resistance is distributed along a pile.<br /><br />Dynamic pile testing originated with the Pile Driving Analyzer, developed in the 1960s to estimate driven-pile capacity with each hammer blow. The method was later applied to drilled foundations, and GRL began researching its use for helical piles in 2010. Dynamic testing is now sometimes proposed instead of static testing, though acceptance remains mixed.<br /><br />The presentation described three testing systems: the APPLE 7, rated up to 75 tons; the APPLE 7–2G, rated up to 150 tons; and the APPLE 6, rated up to 300 tons. These systems use drop weights and can be handled by common site equipment; the APPLE 6 uses a hydraulic clamp to avoid transmitting shock to the crane.<br /><br />Example results showed that increasing drop height generally increased measured impact force, pile set, transferred energy, and compressive force. The reported tests included piles installed to depths of about 45–46 feet, with varying installation pressures and drop heights. Maximum measured compressive forces reached 226 kips in the summarized results.<br /><br />Overall, the seminar presented dynamic testing as a potentially useful way to evaluate helical pile performance and capacity, while noting that it is not universally accepted as a replacement for static testing.

Keywords

dynamic load testing

helical piles

tiebacks

anchors

static load testing

pile capacity

pile driving analyzer

compressive force

drop weight testing

GRL Engineers