非平衡开挖下隔离桩性能分析

Performance analysis of isolation piles under unbalanced excavation

基坑非平衡开挖方式将对隔离桩性能产生极大影响。本文以杭州地铁某地下车站为背景,结合基坑开挖过程中的非平衡开挖及基坑所处软土地层的实际情况,采用PLAXIS 2D建立有限元模型,通过调整隔离桩间距、长度及与地连墙间距,模拟非平衡开挖对隔离桩变形及受力的影响。研究结果表明:隔离桩桩身变形受地面超载影响很大;隔离桩桩身变形及压缩受桩长及隔离桩至围护结构距离的影响较小;随着桩墙中心距的减小,隔离桩桩身弯矩不断增大;当桩长超过支挡结构长度后隔离桩身出现反弯点。本文研究结果可为深基坑工程设计提供一定的借鉴与参考。

The unbalanced excavation method of foundation pit will have great influence on the performance of isolation piles.Based on the background of an underground station in Hangzhou subway,combined with the actual situation of unbalanced excavation during the excavation of the base pit and the soft soil stratum where the base pit is located,the finite element model is established by PLAXIS 2D,and the influence of unbalanced excavation on the deformation and stress of the isolation piles is simulated by adjusting the spacing,length and distance from the even wall.The results show that the deformation of isolation pile body is greatly affected by ground overload;The deformation and compression of the isolation pile body are less affected by the pile length and the distance from the isolation pile to the envelop enclosure;With the decrease of the center distance between piles and walls,the bending moment of isolation piles increases continuously.When the length of the pile exceeds the length of the retaining structure,the anti-bending point appears in the isolation pile body.The results can provide references for the engineering design of deep base pit for the purpose of deformation.