摘   要：为了更准确找出在静力条件下桩身轴力的递变规律，以四桩模型下单桩所受荷载为标准，分别对单桩模型、双桩模型、三桩模型的上部结构进行设计，使它们在静力条件下单桩受力同四桩模型条件下的单桩受力相同，然后在不同地震波形及其相对应的不同加速度峰值条件下对这四类桩型进行数值模拟。研究结果表明，随着地震加速度峰值的不断增大，各桩型的轴力值也在逐渐增大，距桩顶5倍桩径处轴力增加明显；在同一地震峰值作用条件下，各桩型桩身轴力增量都在不断减小；地震波与正弦波作用下的桩身轴力分布规律基本相同，正弦波下的各桩型桩身轴力值比地震波下的轴力值偏大。

Abstract: In order to find the alternation rule of pile axial force precisely, regarding the single pile load in four-pile model under static conditions as the standard, upper structures of the one-pile model, two-pile model, three-pile model are designed to make sure that the load of each pile of these models is the same as the load of single pile in four-pile model, and the numerical simulations for the four pile type are carried out under different seismic waveforms and different peak acceleration. The results show that axial force of each pile type increases gradually with the increasing of peak acceleration, and the pile axial force increases apparently at 5 times pile diameter to the top. At the same seismic peak value conditions, pile axial forces of all the four pile types decrease. In addition, the distribution rule of the axial force along the pile body under seismic function shows that the distributions of pile axial forces under seismic wave and sine wave are basically the same, but the pile axial force of the each pile body under sine wave is bigger.