基于能量法的填土地基单桩负摩阻力计算方法  

Calculation Model of Bearing Capacity of Pile in Deep Fills Based on Energy Method

作　　者：代坤 DAI Kun(China Railway Liuyuan Group Co.,Ltd.,Tianjin 300308, China)

机构地区：[1]中铁第六勘察设计院集团有限公司,天津300308

出　　处：《科学技术与工程》2021年第34期14719-14725,共7页Science Technology and Engineering

基　　金：重庆市建设科技计划(2017-1-1-4)。

摘　　要：深厚填土地基因土体固结沉降导致桩基产生负摩阻力,负摩阻力会造成桩身的沉降量过大和承载力降低。针对能较准确计算深厚填土场地基桩负摩阻力方法研究成果不足的问题,通过不同法向应力下的土-混凝土界面剪切试验讨论了桩侧摩阻力的发挥机理,并考虑桩侧摩阻力随深度的分布规律,提出结合双曲线模型和有效应力法的桩侧摩阻力分段计算模型。然后,基于桩-土体系的能量传递,建立负摩阻力条件下基桩的能量平衡方程,进而导出同时考虑桩-土相对位移和桩-土体系势能变化的桩身轴力和位移计算表达式。以某桩基现场试验项目进行计算,将理论计算结果与试验实测结果对比分析,结果表明:理论计算所得桩身轴力沿深度变化曲线与试验结果基本吻合,本方法能够较准确的分析深厚填土地基中基桩的力学特性。The consolidation settlement of deep filled foundation makes the pile produce negative friction.Negative friction increases the settlement and reduces the bearing capacity of the pile.At present,there are insufficient methods to accurately calculate the negative friction of piles in deep fills.The mechanism of pile lateral frictional resistance based on shear tests at the soil-concrete interface under different normal stress conditions was discussed.And according to the distribution law of pile side friction with depth,a segmented calculation model of pile side friction combined with hyperbolic model and effective stress method was proposed.Then,based on the energy transfer of pile-soil system,the energy balance equation of pile considering negative friction was established.Finally,the calculation expressions of pile axial force and displacement considering both pile-soil relative displacement and pile-soil system potential energy were derived.A pile foundation field test project was used as an example for calculation,the theoretical calculation results were compared with the test results.The results show that the theoretical calculation of the pile shaft force variation curve along the depth is basically consistent with the test results,and the method can analyze the mechanical characteristics of the foundation pile in deep fill foundation more accurately.

关 键 词：深厚填土 基桩 负摩阻力 能量法 数值计算 

分 类 号：TU473.1[建筑科学—结构工程]