大规模群桩基础相互作用近似解耦方法

针对传统弹性理论法过高地估计了桩-桩相互作用效应，基于杆件有限单元法建立了半无限土体中群桩基础的桩侧剪应力求解方程，通过简化桩-桩的相互作用效应，将群桩基础桩侧摩阻力的求解方程近似解耦，实现了群桩基础桩身剪应力和位移的快速求解目标。通过两桩相互作用系数以及柔性承台下群桩基础差异沉降的对比分析，验证了该简化方法的合理性。参数分析结果表明，该简化方法计算得到的相互作用系数与严格的边界积分方程法解答较为接近，稍小于Poulos弹性理论法的计算结果；柔性承台下群桩的差异沉降在桩间距较小时与经典解答较为接近，而在桩间距较大时则存在一定的差别。该简化方法大幅减少了群桩计算工作量，适用于大规模群桩基础的快速计算要求。

An approximate decoupling method for interaction of large-scale pile groups

In view of the problem that the conventional elastic method tends to overestimate the pile-pile interaction, the finite element method is applied to establish the shear stress equation of pile shaft for pile groups in the semi-infinite soil mass. The equation is decoupled by considering the pile-pile interaction in a approximate way, a simplified analysis method is proposed for calculating the pile shaft shear stress and displacement to implement the high-efficient analysis of large-scale pile groups. The problem of interaction between two piles and differential settlement of pile groups with flexible cap are analyzed; and then comparisons with the existing results are presented. Parameters analysis show that the interaction factor calculated by the present method is more close to the result given by a rigorous integral equation method, while slightly smaller than Poulos’s results. The differential settlement ratio of pile group with flexible cap in three cases are relatively close to the existing conventional result when the pile spacing is small; while with the increase of pile spacing, a slight difference occurs between the methods. The results show that the present method can greatly reduce the amount of calculation and can be applied to the efficient analysis of large-scale pile groups.