Finite element analysis of helical piles subjected to axial impact loading

Two-dimensional (axi-symmetrical) dynamic finite element analyses were performed to simulate the static load tests (SLT) and High Strain Dynamic Load Tests (HSDT) conducted on helical piles to gain better understanding of their behaviour during the tests. The finite element models were verified using the results of two case histories involving SLT and HSDT on large diameter helical piles. The finite element models simulated the helical piles installed in both sand and clay soils and were used to characterize soil-pile interaction during the tests and to establish the derived static load-settlement curves for both types of soil. The verified numerical models were employed to perform a comprehensive parametric study to investigate the influence of various material and geometric aspects of the soil-pile-hammer system on the dynamic response of helical piles during axial impact loads. The results from the parametric study were used to formulate guidelines for the design of effective HSDT on helical piles as well as on driven piles.