考虑渗流作用的深基坑桩锚支护结构内力和变形研究

Internal Force and Deformation of Pile Anchor Retaining Structure in Deep Foundation Pit Considering Seepage

以天水市某深基坑为研究背景,对预应力锚索内力、支护桩侧向位移及基坑周边地表沉降进行了监测;采用MIDAS/GTS有限元分析软件,分别建立考虑渗流和不考虑渗流两种深基坑开挖支护分析模型,对深基坑开挖过程中桩锚内力和变形过程进行了模拟计算,进一步探讨了在渗流作用下深基坑位移、内力随基坑开挖深度的变化规律。结果表明:在桩锚支护结构体系下,有限元分析结果与实际监测结果的预应力锚索内力、支护桩侧向位移及基坑周边地表沉降变化趋势基本一致,均随着基坑开挖深度的增加呈现增大趋势,直到基坑开挖完成后逐渐趋于稳定;对比分析表明考虑渗流作用分析结果较不考虑渗流作用更为不利。

By taking a deep foundation pit in Tianshui City as an examply,the internal force of prestressed anchor cable,lateral displacement of supporting pile and surface settlement around the foundation pit are monitored first.Then,the finite element analysis software MIDAS/GTS is adopted to establish two kinds of deep foundation pit excavation and support analysis models with and without seepage respectively,the internal force and deformation of pile anchor in the excavation process of deep foundation pit are simulated and calculated,and the variation laws of displacement and internal force of deep foundation pit with excavation depth under seepage is further discussed.The results are as follows.The change trend of internal force of prestressed anchor cable,lateral displacement of supporting pile and surface settlement around the foundation pit are basically consistent with the actual monitoring results under the pile anchor supporting structure system,which all show an increasing trend with the increase of excavation depth,and gradually tend to be stable after the completion of foundation pit excavation.The comparative analysis shows that the analysis results considering the seepage effect are more unfavorable than those without considering the seepage effect.