桩撑支护软土深基坑大变形固结有限元分析

FEM Analysis on Large Deformation Consolidation for Deep Foundation Pit in Soft Soil with Pile-strut Bracing

结合广州某桩撑深基坑支护工程,运用ABAQUS有限元软件,对基坑进行考虑渗流作用的大变形固结研究,分析了基坑开挖过程中,支护桩桩身和坑后土体的水平位移、坑底隆起量、周边地表沉降量、支撑轴力及支护桩弯矩等的变化规律。结果表明:大变形固结有限元分析得到的桩身水平位移等变形值与实测结果吻合较好,由于考虑了渗流作用模拟值略大于实测值;大、小变形分析得到的支护桩桩身弯矩结果比较接近,二者相差0.1%左右;支撑轴力的大变形模拟结果与实测结果相差不大,轴力的变化规律和开挖过程相吻合。大变形固结分析,能很好地模拟基坑开挖过程中土体和支护结构的真实性状。

Depending on a project of deep foundation pit with pile-strut bracing in Guangzhou,the study of large deformation consolidation in relation to the pit taking seepage into consideration was conducted with ABAQUS,a FEM software,to analyze during the excavation the change laws of horizontal displacement of the supporting pile body and the soil mass behind the pit,pit bottom uplift,surrounding surface settlement,axial force of the struts and bending moment of the supporting pile.The results show that the horizontal displacement of pile and other deformation values from the analysis herein agree with the measured values well since the simulated values taking seepage into consideration are just slightly more than the measured values;the values of bending moment of pile from large and small deformation analysis are so close that the difference between the both is about 0.1％ ; the value of axial force of strut from the analysis herein has little different from the measured value,and the change law of axial force is consistent with the excavation.The large deformation consolidation analysis may simulate the real characters of the soil mass and bracing structure in excavation of foundation pit.