圆砾-泥岩组合地层坑中坑开挖对双排桩的影响

为研究双排桩在南宁圆砾-泥岩组合地层中的支护特性,以南宁地铁4号线某深基坑工程为依托,运用ABAQUS有限元软件和现场监测数据进行分析,得出双排桩在该地层有较好适用性的结论.然后在此基础上,进一步探讨坑趾系数、深度比在影响阈值左右范围变化以及不同土体强度弱化百分比的工况下,坑中坑开挖对双排桩的影响.结果表明各因素对双排...

Influence of Pit-in-Pit Excavation on Double-row Piles in Composite Stratum of Round Gravel and Mudstone

With a deep foundation pit project of Nanning Metro Line 4, we studied the supporting characteristics of double-row piles in round gravel mudstone composite stratum in Nanning using ABAQUS finite element software and field monitoring data, and concluded that double-row piles are well applicable in the round gravel mudstone composite stratum. We further investigated into the influence of pit-in-pit excavation on double-row piles under the conditions of different soil strength weakening percentages and the variations of pit toe coefficient and depth ratio around thresholds. Our findings suggest that the weakening of soil strength has the greatest influence on the supporting effect of double-row piles, followed by pit toe coefficient and depth ratio in sequence. Meanwhile, we propose to take whether the maximum increase percentage of lateral displacement of double-row piles exceeds 20% as the criterion to assess the influence degree of inner pit excavation on the safety and stability of foundation pit. In addition, by analyzing the failure modes and causes of the foundation pit under corresponding working conditions of each parameter, we gave corresponding countermeasures.