桩基础承载力室内试验与数值计算研究  

Research on the Failure Characteristics of Pile Foundation by the Laboratory Experiment and Numerical Calculation

作　　者：刘祥沛 董天文[1,3] 郑颖人[1,3] 

机构地区：[1]后勤工程学院军事土木工程系,重庆400041 [2]岩土力学与地质环境保护重庆重点实验室,重庆401311 [3]重庆市地质灾害防治工程技术研究中心,重庆401311

出　　处：《地下空间与工程学报》2016年第3期719-728,共10页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(No.51178457)

摘　　要：为深入研究桩基础破坏特征,解决桩基础承载机理和破坏条件问题,自行设计桩基础承载力室内试验,对桩顶外力、位移、桩侧摩阻力与桩底反力进行了全方位测试。采用临近桩基破坏时减小加载量的方法,结合数值模拟极限方法分析,在两种方法所得P-s曲线中可以找到陡降的破坏点。两种方法的极限承载力、桩底反力吻合较好,表明室内试验可信,数值极限方法可行。依据以上两种方法,提出了桩基的三点破坏特征:(1)破坏时桩顶位移突变,破坏后有时会有所反弹;(2)破坏时桩底反力突变并出现明显反弹;(3)破坏时桩侧摩阻力出现先降低后增大现象。这些特征表明桩基破坏后桩侧与桩底承载力还将提高,使桩基仍然维持力学平衡状态,表明桩基这种破坏特征与其他基础形式不同。综合桩基础破坏特征,提出应按第一次桩顶位移突变作为控制桩基础承载力的条件。本次研究只是探索,还需现场试验的验证。The bearing characteristics and damage conditions of pile foundation are the base for the establishment of failure mode and the determination of ultimate load.For research on damage characteristics of pile foundation,the external force and displacement of pile head,the friction resistance of pile side and the counter force of pile bottom are determined with the self-designed laboratory experiment on pile foundation bearing capacity. Numerical limit method is carried on to simulate it,the failure point at the steep drop can be seen in the P-s curve in both the test and numerical method if the load is decreased when pile foundation is close to failure.The results of ultimate bearing capacity and counter force from the test and numerical simulation are in good agreement,which show the tests are reliable and the numerical limit methods are feasible. According to the two methods above,three failure characteristics of the pile foundation was gained： 1. during foundation destruction,the displacement of pile top presented mutation,sometimes rebounding occurred after destruction; 2. it would appear mutation of counter force and significant rebound on the pile base; 3. the friction resistance of pile side would increase after decrease on its damage. These characteristics indicate that the bearing capacity of the pile side and the pile bottom can be enhanced after the failure of pile foundation,the balance of the pile foundation is still maintained,and the difference between pile foundations and other foundations is revealed. Comprehensive consideration of the failure characteristics of pile foundation,the conditions for controlling the bearing capacity of the pile foundation are proposed based on the first pile top displacement.

关 键 词：桩基础 破坏机理 承载力 室内试验 数值计算 

分 类 号：TU473.1[建筑科学—结构工程]