深基坑开挖过程中立柱隆起问题数值模拟分析

Numerical Simulation Analysis of Column Uplift in Deep Foundation Excavation Process

深基坑开挖过程中立柱、立柱桩会产生隆起,相邻立柱间的过大差异隆沉对内支撑体系稳定性产生不利影响。结合郑州地区某深基坑工程,采用有限元法计算分析了立柱及立柱桩的隆起问题,深入探讨了基坑开挖过程中立柱隆起、立柱桩工作特性的变化规律,分析了立柱隆起对支撑体系内力的影响规律。计算结果表明,立柱隆起主要受基底土体隆起变形的控制,并随着基坑开挖深度的增加而增大;立柱桩越长,立柱隆起量就越小,增加立柱桩桩长是降低立柱隆起量的有效措施,但同时也会增大桩身拉应力;立柱隆起会显著改变支撑体系的内力分布规律,且立柱过大的差异沉降会显著增大支撑体系的内力。工程设计时,建议合理选择立柱桩桩长来控制立柱隆起,避免相邻立柱桩桩长出现过大差别。

In the process of deep foundation excavation,the column and the erect column pile will produce the problem of uplift,and the large difference between the adjacent columns will have an adverse effect on the stability of the internal support system.Combined with a deep foundation excavation project in Zhengzhou City,Henan Province,the finite element method is used to calculate and analyze the uplift of the column and the erect column pile.The variation law of the uplift of the column and the working characteristics of the erect column pile during the excavation of the foundation excavation were discussed in depth.The influence of the uplift of the column on the internal force of the support system is analyzed.The calculation results show that the uplift of the column is mainly controlled by the uplift deformation of the base soil and increases with the increase in the excavation depth of the foundation excavation.The longer the erect column pile,the smaller the uplift of the column.It is an effective measure to reduce the uplift of the column by increasing the length of the erect column pile,which,however,will also increase the tensile stress of the pile.The uplift of the column will significantly change the internal force distribution of the support system,and the excessive differential settlement of the column will significantly increase the internal force of the support system.Therefore,in engineering design,it is recommended to reasonably select the length of the erect column pile to control the uplift of the column and avoid excessive differences in the length of adjacent erect column piles.