基坑开挖回弹对工程桩承载性状的影响分析

Influence of Excavation-induced Rebound on the Bearing Behavior of Foundation Pile

工程桩施工后的地下空间开挖可能会显著影响既有桩基承载性状。基坑开挖后,受土体回弹效应的影响,桩侧摩阻力呈上部为正、下部为负的分布形式。为了单独分离出这种特殊分布对桩基后续承载的影响,通过建立有限元对比模型的方法进行探究。结果表明,若不考虑基坑开挖回弹对工程桩的影响,会低估桩趋于极限状态时的桩顶沉降量,而桩的极限承载力几乎不受影响。

Underground-space excavation following the installation of foundation pile may significantly affect the original behavior of the pile. After excavation,the distributions of pile shaft friction responding to soil rebound are positive and negative frictions along the upper and lower portions,respectively. In order to separately investigate the effect of such special distribution on the following bearing behavior of the pile,a finite-element-based contrast model is established in this study.The results show that the excavation-induced shaft friction has little effect on the ultimate pile capacity; however,removal of such friction will underestimate the pile-head settlement towards limit-state.