开挖条件下非均质地基中被动群桩水平反应分析

地下工程开挖包括基坑开挖、隧道开挖等,邻近建筑物的桩基因开挖引起的土体位移会产生弯矩和变形。基于两阶段分析方法,考虑土体的非线性,采用Winkler地基模型模拟被动单桩桩土之间的相互作用,运用有限差分法进行求解以考虑地基土的分层特性,并基于简化Mindlin方程考虑群桩的桩–桩相互影响,计算被动群桩的遮拦效应,从而得到开挖条件下被动群桩水平反应的简化分析方法。最后将基于两阶段分析方法的差分解法与边界元解、现场实测结果、离心机实验结果等进行对比,验证了该方法的合理性及实用性。

Lateral response of passive pile groups due to excavation-induced soil movement in stratified soils

Lateral soil movement induced by excavation or tunneling might adversely affect any nearby pile foundation systems.In this paper,a simple analysis solution was outlined for computing the lateral response of passive pile groups subjected to urban underground excavation.Based on a two-stage method,nonlinear analysis with a Winkler model was adopted to study the effect of pile-soil interaction,combined with finite difference method in the case of multi-layered soils.A specified free-field soil movement profile was used as an input.Then,the governing equation of group piles was obtained considering the shielding effect in pile groups by the simplified Mindlin’s equation.Comparisons were made among the behaviors obtained from boundary-element analysis,in-situ observations,centrifuge model tests and those computed by the proposed finite difference method.Generally,a satisfactory prediction of the lateral response of passive pile groups could be given by the proposed method.