考虑荷载P-Δ效应的陡坡段桥梁基桩变形计算  

Deformation Calculation of Bridge Foundation Pile in Steep Slope Section Considering Load P-Δ Effect

作　　者：杨明辉[1] 李俊儒 付大喜 YANG Minghui;LI Junru;FU Daxi(College of Civil Engineering,Hunan University,Changsha 410082,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]北京交通大学土木建筑工程学院,北京100044

出　　处：《湖南大学学报（自然科学版）》2022年第7期168-177,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)。

摘　　要：位于陡坡段的基桩由于有较长的自由段以及临空面土体抗力的缺失,变形具有明显的P-Δ放大效应.引入变分原理,考虑陡坡段基桩承载的复杂性,假定土体位移是沿基桩径向的非线性衰减模式,建立了陡坡段三维基桩-土体系统总能量控制微分方程.在此基础上,结合不同边界条件及桩土位移协调条件,得出了复杂承载情况下陡坡段基桩变形的半解析差分解答,该解答可充分考虑各项荷载作用下的陡坡段基桩变形的P-Δ效应.为验证理论的正确性,开展了陡坡段基桩的轴横荷载下单桩的室内模型加载试验,将理论计算值与实测值进行了对比.结果表明,理论解答与试验测试结果吻合较好.最后,对影响陡坡段基桩P-Δ放大效应的各影响因素进行了定量分析.分析表明,陡坡段桥梁基桩的P-Δ放大效应随轴横向荷载比与桩顶自由长度增大而显著增大,随着土体刚度的增强而有所减小,同时陡坡坡度角增大对P-Δ效应有明显的提升作用.Due to the long free section and the lack of soil resistance on the free surface of the foundation pile located on the steep slope,the deformation has an obvious P-Δ amplification effect. In this paper,introducing the energy variational principle,considering the complexity of the pile bearing and pile-soil interaction in the steep slope section,and assuming that the soil displacement is a nonlinear attenuation mode along the radial direction of the foundation pile,the total energy control differential equation of the three-dimensional foundation pile-soil system in the steep slope section is established. On this basis,combined with different boundary conditions and the coordination conditions of pile-soil displacement,the semi-analytical energy method solution for the deformation of the foundation piles on steep slopes under complex bearing conditions is obtained based on the finite difference method,and the solution can fully consider the P-Δ effect of the pile deformation in the steep slope section under various loads.Then,the indoor model loading verification test of the single pile under the axial and lateral load on the steep slope section was carried out,and the theoretical calculation value was compared with the measured value. The comparison results show that the theoretical solution in this paper is in good agreement with the test results. Finally,a quantitative analysis of the influencing factors of the P-Δ amplification effect of foundation piles on steep slopes is carried out. The results show that the P-Δ amplification effect of bridge foundation piles on steep slopes increases significantly with the axial and lateral load ratio and the free length of the pile top but decreases with the increase of soil stiffness. At the same time,the slope gradient has a significant increase influence on the P-Δ effect.

关 键 词：陡坡 桥梁基桩 P-Δ效应 最小势能原理 模型试验 

分 类 号：TU473.1[建筑科学—结构工程]