基于能量法的基桩变形P-Δ效应模拟分析  

Simulation Analysis on P-Δ Effect for Piles Based on Energy Method

作　　者：杨明辉[1] 李勇智 罗宏[1] YANG Minghui;LI Yongzhi;LUO Hong(Geotechnical Engineering Institute,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学岩土工程研究所,湖南长沙410082

出　　处：《湖南大学学报（自然科学版）》2020年第5期48-57,共10页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(51278184,51678230);教育部新世纪优秀人才支持计划项目(NCET-13-194);湖南省科技重点研发项目(2015CK3003)。

摘　　要：复杂荷载下基桩受力分析是桩基设计计算重要内容之一.引入能量原理,针对基桩荷载倾斜与偏心的特殊情况,并考虑土体的成层特性,建立了三维基桩-土体系统能量控制微分方程.在此基础上,结合不同边界条件及桩土位移条件,基于有限差分方式得出了倾斜偏心荷载下基桩位移的半解析解答,该解答可充分考虑轴向与横向荷载共同作用对基桩变形的P-Δ放大效应.而后,开展了倾斜偏心荷载下单桩的室内模型加载验证试验.对比结果表明,本文理论解答与试验测试结果吻合较好,较好地模拟了组合荷载下基桩变形P-Δ放大效应.最后,对影响基桩P-Δ放大效应的主要因素进行了分析,结果表明,轴、横向荷载相对大小、桩顶自由段长度、桩身刚度及浅层地基土刚度等都对P-Δ放大效应有较大影响.The force analysis of piles under complex loads is one of the important contents in the design and calculation of pile foundation.In this paper,a energy control differential equation of three-dimensional pile-soil system is established according to the energy principle,considering the special case of tilting and eccentricity of pile loads as well as the layering characteristics of soils.On this basis,combined with different boundary conditions of pile and displacement conditions of pile and soil,a semi-analytical solution of pile displacement under inclined and eccentric loads is obtained based on finite difference method.The solution can fully consider the P-Δ amplification effect of pile deformation.Then,an indoor model loading test of single pile under inclined eccentric load is carried out to validate the solution.The comparison results show that the theoretical solution and the experimental test results are in good agreement,and the P-Δ amplification effect of the pile deformation under combined load is well simulated.Finally,the influencing factors affecting the P-Δ amplification effect of the piles are analyzed.The results show that the relative magnitude of the axial and lateral loads,the length of the free section of the pile,the stiffness of the pile and the stiffness of the surface soil all have a significant impact on the P-Δ amplification effect.

关 键 词：单桩 倾斜偏心荷载 最小势能原理 变分原理 P-Δ效应 

分 类 号：TU473.1[建筑科学—结构工程]