Comparison between high strain dynamic and static load tests of helical piles in cohesive soils

Abstract

Helical piles provides an attractive alternative to conventional pile types such as driven steel open-pipes and concrete piles by improving their axial compressive and tensile resistances. Static load testing is often used to validate helical pile design and as a proof test for production piles. In the current study, the suitability of High Strain Dynamic Testing (HSDT) was investigated. Both helical piles and driven steel open-pipes were installed and high strain dynamic pile load tests were performed on both types. Dynamic pile testing was used to assess static load-bearing capacities of both driven and helical piles. Dynamic data were also used for the determination of Smith soil parameters such as soil quake and damping parameters using CAPWAP signal matching program. Full scale static pile load testing was also performed for both driven pipes and helical piles. The results of static load tests were used to examine the axial capacities obtained using dynamic testing for torque driven helical piles. Examination of the full scale static load test data and CAPWAP analyses suggested that HSDT could provide a suitable tool to assess static helical pile capacities.