Machine induced dynamic field responses of group pile with different pile arrangements

Abstract

The main objective of the current investigation is to study the dynamic behaviour of a 3-pile group with different loading direction under coupled (horizontal and rocking) excitations. To accomplish this objective, machine-induced field excitation tests are conducted on small-scale hollow steel piles. The 3-pile group is driven into the ground in a triangular arrangement with 3d spacing. Two different soil-pile setups, i.e., Pile Group-I and Pile Group-II, are created based on dynamic force directions. In the case of Pile Group-I, the forces are applied to the direction of the median of the triangle, and for Pile Group-II, the forces are applied to other directional loads. From the test results, it is found that the resonant peaks of horizontal and rocking amplitudes for Pile Group-I are lower than Pile Group-II. In the case of resonant frequencies, the values of Pile Group-I are observed to be the same or a little bit higher as compared to Pile Group-II. It is found that the dynamic soil-pile-soil interaction effect is more prominent for Pile Group-II than for Pile Group-I. For numerical investigation, the continuum approach method is utilised with the inclusion of a dynamic group interaction factor to predict the dynamic coupled responses in terms of frequency and amplitude for these two soil-pile setups. To understand the behaviour of pile groups, boundary zone parameters and variations of impedance parameters (stiffness and damping) with operating frequencies are also measured using this theoretical approach.