大直径超长钻孔灌注桩承载特性试验研究

摘要

Research purposes; To analyze the behaviors of axial load transmission, the distribution of lateral friction resistance and the performance of resistance at pile end under different load action, to master the load transfer characteristics and bearing mechanism of large - diameter and overlength bored pile , and to provide reference and guidance for improving the design method of large - diameter and overlength bored pile.Research conclusions: The axis force of large - diameter and lengthy bored pile reduces from the upper portion of pile to the bottom portion, the rate of reduction indicates the magnitude of lateral friction resistance of pile. The function of lateral friction resistance at the upper portion of pile takes precedence of the bottom portion. Moreover, the majority of the load is born by lateral friction resistance of pile for the large - diameter and lengthy bored pile, and the magnitude of resistance at pile end is usually very small. Therefore, most of the large - diameter and lengthy bored piles are friction piles or end - bearing friction piles.%研究目的:分析大直径超长钻孔灌注桩在不同荷载条件下的桩身轴力分布规律、桩侧摩阻力分布及发挥特性、桩端阻力发挥特性,掌握大直径超长钻孔灌注桩竖向受力机理及承载特性,为完善大直径超长钻孔灌注桩的设计方法提供借鉴和指导.研究结论:大直径超长钻孔灌注桩桩身轴力从桩顶到桩端逐渐衰减,其衰减的快慢反映了桩侧摩阻力作用的大小,并且桩身上部的摩阻力先于桩身下部摩阻力及桩端阻力优先发挥;此外,大直径超长钻孔灌注桩的桩端阻力通常较小,其桩顶荷载大部分由桩侧摩阻力承担,按桩的荷载传递机理分类通常属摩擦桩或端承式摩擦桩.