受大面积堆载影响负摩擦桩的Q-S曲线分析  

Analysis of Q-S curve on negative frictional pile under large-scale vertical loads

作　　者：魏鉴栋[1] 凌道盛[1] 陈云敏[1] 

机构地区：[1]浙江大学岩土工程研究所

出　　处：《浙江大学学报（工学版）》2007年第1期166-170,175,共6页Journal of Zhejiang University：Engineering Science

摘　　要：针对在大面积堆载情况下,工程桩部分桩身会因周边土体沉降出现负摩阻力从而改变工程桩的承载特性这一问题,通过对中性点和负摩阻力的分析,提出了从场地工程试验桩Q-S曲线来获得受负摩阻力作用下工程桩的Q-S曲线的方法.采用桩筏有限元软件对工程实例进行了计算分析,验证了该方法的可行性.结果表明,中性点深度的确定是获得负摩擦桩Q-S曲线的关键,不同深度的中性点可以得到不同的Q-S曲线;在相同荷载作用下,中性点深度越深,负摩擦桩越早于正常工作桩屈服,筏板基础的沉降和桩身最大轴力越大.从场地工程试验桩的Q-S曲线来获得受负摩阻力作用下工程桩的Q-S曲线的方法,为大面积堆载下受负摩阻力作用工程桩的承载力设计提供了依据.The negative friction existing on the surface of working single piles will change their vertical capacity character, when the field apparently settled under large scale vertical loads. The negative friction was calculated when the neutral point was on different depth, a new method was introduced to get the Q-S curve of negative frictional pile from the Q-S curve of field -tested pile. Calculation proved the validity of this method. The results showed that the neutral point depth is the key to fixing the Q-S curve of negative frictional pile. Different depth of neutral point will yield different Q-S curves; and the deeper the neutral point depth, the greater the foundation settlement and pile axial force. One case study was carried out to show the application of the present method for designing the capacity of negative frictional piles.

关 键 词：负摩阻力 桩 中性点 Q-S曲线 

分 类 号：TU473[建筑科学—结构工程]