基坑开挖与降水对坑底工程桩影响的数值分析

Numerical Analysis of Effect of Dewatering and Excavation on Piles in a Pit

深基坑开挖一般会伴随超长密集群桩的施工。当基坑坑底存在大量工程桩时,基坑开挖与降水对桩基的影响较为明显。为了研究大面积基坑开挖卸荷与降水对坑底群桩受力变形性状的影响,利用数值分析软件(ABAQUS)对上海市某基坑工程进行模拟分析,并探讨了基坑开挖与降水对坑底群桩变形影响的规律。计算结果表明,不考虑降水情况下和考虑降水情况下基坑中心点处坑底桩桩顶的竖向回弹和桩土相对位移是有差异的,采用不考虑降水的总应力法计算的结果偏大,而采用考虑降水的有效应力法计算的结果更符合工程实际。

Foundation pit excavation is normally followed by the construction of super-long compact pile groups.When there are large numbers of engineering piles on the bottom of the foundation pit,the excavation of foundation pit obviously impacts the piles.In order to study the effect of large-scale excavation and unloading,and force-deformation characteristics of the pile groups,the numerical analysis software（ABAQUS） was used to simulate a foundation pit project in Shanghai.The influence of the dewatering and excavation of foundation pits on pile groups was calculated and analyzed.The results showed that vertical rebound on the top of the piles and displacement between pile and soil considering dewatering or not were different.The result was too large without consideration of the dewatering,but it compied with engineering practice with consideration of dewatering.