低承台群桩基础竖向承载特性及优化设计

STUDY ON THE VERTICAL BEARING CHARACTERISTICS AND PILE LENGTH OPTIMIZATION OFLOW CAP PILE GROUPS

针对等刚度群桩基础易出现差异沉降、承台弯矩增大等问题,考虑总桩长一定且土体刚度沿深度线性增加的条件下,设定8种典型的群桩基础方案。运用PLAXIS 3D有限元软件建立群桩基础分析模型,结合现场大比例尺群桩载荷试验验证文中数值模拟法的合理可行性,进而针对5×5低承台群桩基础分析桩土刚度比、桩间距等因素对基础轴向刚度比和差异沉降比的影响。研究结果表明,当桩长配置为10、32、16、32、10m时,桩长配置有利于增加基础刚度;当桩长配置为14、24、24、24、14m时,桩长配置有利于减小基础差异沉降。研究为群桩基础的桩长优化设计提供一定的参考。

Regarding the issues of differential settlement and increased bending moment in low cap pile groups withequal stiffness, eight typical group foundation schemes are established under the condition of fixed total pile lengthand linear increase of soil stiffness along the depth. The PLAXIS 3D is used to create the analysis model of the pilegroups, and the rationality of the method proposed in this paper is validated through the field-scale pile group loadtests. Furthermore, the influence of factors such as pile-soil stiffness ratio and pile spacing on the axial stiffness ra⁃tio and differential settlement ratio of the foundation is analyzed for a 5×5 low-cap pile foundation. The results showthat when the pile lengths are configured as 10、32、16、32m and 10m, the pile length configuration is advanta⁃geous for increasing the foundation stiffness. When the pile lengths are configured as 14、24、24、24m and 14m, thepile length configuration is advantageous for reducing differential settlement of the foundation. The study may pro⁃vide the reference for the optimal design of pile lengths for group pile foundations.