桩周土及桩间距对桩基地震反应的影响

用整体动力有限元方法分析桩周土及桩间距对桩基地震反应的影响。在土体侧向的边界节点处用弹簧并联阻尼器来进行模拟；在土体平面应变单元和桩体梁单元连接处，用补充约束方程的方法进行节点耦合，使2种不同类型单元满足连续条件。结合典型工程实例选择桩、土、结构及荷载参数，重点研究了上层软土厚度的变化、软土地质参数的变化及桩间距的变化对桩基地震反应分析的影响。当上层软土的厚度达到一定值时，在土层软硬分界处桩身的内力将达到最大值。当上层土体更为软弱时，在土层软硬分界处桩身的内力会有较大的增加。桩间距适当减小时桩身的峰值内力会减小。

Influence of Seismic Response on Piles due to Pile-surrounding Soil and Spacing Between Adjacent Piles

The influence of seismic response on piles due to pile-surrounding soil and spacing between adjacent piles was studied with the method of whole dynamic finite element under the seismic condition.The elastic spring-damper was used to simulate soil side boundary.Input restraint joint was used to settle continuous conditions of the different type of connective unit.Subsequently,with the proposed method,selecting pile-soil-structure and the load parameter,emphasizing that the changes of the upper layer soft soil thickness,the soft soil geological parameter and pile spacing was impacted on the pile foundation earthquake response analysis.When the thickness of the upper soft soil layer reach a certainty value,the internal force of the pile body at soil-hard demarcation section would reach the maximum value.When the upper layer soil was even softer,the internal force of the pile body at soil-hard demarcation section would be increased further.The internal force peak value of pile body would be decreased with reducing spacing of the pile.These conclusions could conduce to the engineering practice.