Evaluating the Capacity of Helical Piles in Clay Tills Using Pile Load Tests

ABSTRACT: This thesis analyzes seven static load tests conducted on helical piles installed in clay till at a site in Northern Manitoba, Canada. Four methods, the Davisson Offset Limit, the Hansen Ultimate Load, the Chin-Kondner Extrapolation, and the Decourt Extrapolation are used to determine the ultimate capacity using the pile load test results. The ultimate capacities obtained were then used to determine the empirical parameter Kt for helical piles in clay tills, this parameter relates the pile capacity of helical piles to the installation torque of the pile. The Davisson Offset Limit and the Hansen Ultimate Load provided consistent and conservative ultimate capacities based on the pile load test results and showed lesser variability in results compared with the Chin-Kondner Extrapolation and Decourt Extrapolation methods. The ultimate loads based from the Hansen and Davisson methods were used to calculate a Kt value. It was determined that a Kt value ranging from 9 m-1 to 11 m-1 is appropriate for evaluating the capacity of a helical pile in clay tills using the installation torque of the pile.