2016 年 2 巻 38 号 p. 1389-1392
In the present study, the nonlinear coupled response of a 6-pile group with different arrangement of piles (length = 3.0 m and spacing = 3d, where d = diameter of pile = 0.114 m) are investigated under varying levels of horizontal harmonic excitation with a static load of 14 kN. Forced coupled vibration tests have been performed on the pile groups with 3 × 2 and 2 × 3 arrangements to obtain the time-acceleration responses for different frequencies of machine and finally from that the frequency-amplitude responses are determined for horizontal and rocking motions separately. The resonant amplitudes of the 3 × 2 pile group are found much higher (approximately 10 % for horizontal and 65 % for rocking mode) than the amplitudes of the 2 × 3 pile group. It is also found that the resonant frequencies of the 3 × 2 pile group are lower than the 2 × 3 pile group for all eccentric moments. The continuum approach with the formulation of group interaction matrix is used to determine the theoretical nonlinear dynamic response of the pile groups after incorporating boundary zone parameters and soil-pile separation lengths. The measured frequency-amplitude responses for both modes of vibrating displacements are compared with the results obtained from theoretical study. The resonant amplitudes (both horizontal and rocking) and resonant frequencies obtained from the analytical approach follow the same trends as observed in the case of dynamic test results. From the results it can be concluded that the effect of dynamic pile-soil-pile interaction is more prominent in the 3 × 2 pile group than the 2 × 3 pile group.
