自平衡试桩法桩基承载力等效转换新方法  

A new equivalent transformation method for calculating the pile bearing capacity on self-balancing test results

作　　者：谭现江 杨高尚[1] 雷明锋[1,2] 陈树林 李玉峰[1,2] 

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中国建筑第五工程局有限公司,湖南长沙410004 [3]山东省建筑科学研究院,山东济南250031

出　　处：《铁道科学与工程学报》2016年第12期2388-2395,共8页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51508575);中国博士后科学基金资助项目(2014M560652;2016T90764);湖南省创新平台与科技人才资助项目(2015RS4006)

摘　　要：在分析自平衡试桩法桩基荷载传递机制的基础上,提出一种新的自平衡试桩法桩基承载力等效转换方法。该方法首先基于Mindlin公式求出桩侧摩阻力在桩周和桩底土体中引起的附加应力,通过考虑附加应力对桩侧土体极限侧摩阻力和桩-土界面初始剪切刚度的影响,并采用双曲线模型模拟桩-土界面剪切模量在桩基沉降过程中的动态变化来改进传统的剪切位移等效转换方法,使其适用于大变形的桩基沉降计算。进而,进一步通过对自平衡试桩法测试数据的反演分析,得到土体初始参数,从而转换获得等效的桩基在静载作用下的荷载-沉降曲线,并以此确定桩基承载力。该方法考虑土体的分层性、非线性、连续性和附加应力的影响,避免了在等效转换过程中引入经验系数。实例分析表明,该方法较既有规范中推荐的精确转换法具有更高的精确性,实际工程应用中,能够充分发挥桩基的实际承载能力。By analyzing the load transfer mechanism of pile foundation, a new method of equivalent conversion of self-balanced test piles is proposed. Firstly, the additional stress caused by the friction of the pile side friction in the soil around the pile and the bottom of the pile is obtained based on Mindlin formula. And the influence of ad-ditional stress on the ultimate lateral friction of the pile side soil and the initial shear stiffness of the pile soil in-terface is considered. The dynamic changes of the shear modulus of the pile and soil interface in the process of pile foundation settlement are simulated by using the hyperbolic model used to calculate the large deformation of the pile foundation settlement. By analyzing the test data of the self-balanced test pile, the initial parameters of the soil are obtained, and the load bearing capacity of the pile foundation under static load is also determined. In this method, the effect of the layered, nonlinear, continuous and additional stress of soil are considered, and the empirical coefficient is avoided. The example analysis shows that the proposed method has higher accuracy than the precise conversion method, which can enhance the actual bearing capacity of the pile foundation.

关 键 词：自平衡试桩法 剪切位移法 附加应力 动态模量 

分 类 号：TU473[建筑科学—结构工程]