Abstract: In order to ascertain the difference of dynamic time-history response between large-diameter, deep-long single pile and pile group foundation under strong earthquake, a large shaking table test was carried out based on the physical project of Haiwen Bridge. The various rules and differences of pile top acceleration, pile top relative displacement, and pile bending moment between the single pile and pile group foundation under four types of seismic waves were studied. The results show that the time-history response of pile top acceleration is double-sided due to the pile group effect. The peak acceleration of pile group is larger than that of single pile, but the peak time lags behind that of single pile by 0.29–1.06 s. The pile top maximum relative displacement of the group pile is significantly smaller than that of the single pile, and there is an obvious lag in the time. Excited by the Kobe wave, the lag time is as long as 3.82 s. The maximum bending moment of the pile group is 7.54%–9.22% less than that of the single pile. Because the single pile is greatly affected by seismic waves, its amplitude of bending moment time-history response is obviously larger than that of the pile group. In the seismic design of pile foundation, the lag characteristic of dynamic time-history response of the pile group foundation can be fully used to design and select the optimal pile type reasonably.

Key words: piles foundation, strong earthquake area, shaking table test, time-history response difference