Dynamic Field Response of Small-Scale Hollow Steel Piles under Machine Induced Vibrations

  • Shiva Shankar Choudhary


The objective of the present study is to understand the dynamic behaviour of frequency-amplitude responses of pile foundations for different eccentric moments under vertical excitation. To accomplish this objective, forced vibration tests have been performed in the field on hollow steel piles (pile length = 3 m, diameter of pile = 0.114 m) under 12 kN static load. Field tests are performed on a small-scale single pile and a 2 2 pile group subjected to rotating machine induced vertical excitation to obtain the vertical frequency-amplitude responses of the pile foundations for different eccentric moments. It is found from the dynamic test results that the frequency-amplitude responses indicate a single resonant peak within the range of the dynamic testing for both single and group pile. It is also found that the dynamic response curves show nonlinear behaviour of pile foundations as the resonant frequencies are decreased with the increase in eccentric moments and the increase in resonant amplitudes are not proportional to the increase of eccentric moments. The basic characteristics of frequency-amplitude responses are found similar for both single and 2 2 pile group. However in the case of pile group, the values of resonant frequency are found higher and resonant amplitude values are found lower as compared to the single pile because of the higher dynamic stiffness of the pile group than the single pile.