开口环形深基坑围护结构变形监测与数值分析

南京扬子储煤筒仓基坑工程地基中分布有厚度较大的软土层,且该工程基坑为11.40 m深,直径约27.0m的开口圆环形,其中开口段弧长约10.0m.基坑围护结构采用钻孔灌注桩结合环形内支撑的型式.开口段对基坑的变形和稳定性有较大的影响.以该工程为例,采用三维有限元数值分析方法,建立了摩尔-库仑弹塑性模型,进行不同开挖阶段的数值模拟计算,并与监测结果进行了对比.结果表明,计算值与实测值差距较小,变化趋势基本一致,有限元计算的结果是可信的,可为类似工程优化设计与施工提供参考.

Deformation Monitoring and Numerical Analysis of Supporting Structure of Open Ring Deep Foundation Pit

There are thicker soft soil layers distributed in the subsoil of Nanjing Yangzi coal storage silo project which deep foundation engineering excavates a pit with the depth of 11.40 m. The row piles were used as retaining structure with cast-in-situ bored pile and ring beams as struts which are 10. 0 m length of open arc. However, the open sections of ring struts have a great influence on the deformation and stability of foundation pit excavation. Based on this practical engineering, a threedimensional finite element numerical analysis model was established and the soil and the interface elements were modeled as elasto-plastic materials obeying Mohr-Coulomb failure criterion, then staged excavations were simulated and calculated. Compared with monitoring data, the results showed that the difference between calculated values and measured values was negli gible, and the variation trend was almost the same. The calculated results of finite element are reliable, which can be references for design and construction improvement of similar engineering.