复杂深基坑坑中坑稳定性分析与快捷支护技术

Analysis on Stability of Pit in Pit on Complicated Deep Foundation Pit and Quick Support Technology

以临近地铁隧道深基坑为背景,分析了坑中坑不同临边距离与内坑深度对整体基坑变形与稳定性的影响,发现内外坑间距的减小以及内坑深度的增大,引起整体基坑的变形增加,同时稳定性降低,坑中坑特别是临边深坑中坑对基坑的影响不容忽视。设计了坑中坑钢护筒快捷支护组合结构,并对钢护筒焊接与现场沉入施工方法进行了总结。基于有限元法建立了深基坑空间整体协同计算分析模型,模拟了多道支护体系的三维空间协同作用状态,发现了整体基坑支护体系的薄弱部位。该方法可为复杂支撑体系深基坑的整体稳定性分析和基坑开挖施工对周围环境影响的评估提供参考。

In the setting of deep foundation pit near the subway tunnel,the impact of pit in pit with different edge distances and inner depth on the deformation and stability of the whole foundation pit were analyzed,and it is found that the decrease of the distance between the inner and outer pits and the increase of the inner depth lead to the increase of the deformation of the whole pit,at the same time,the stability of deep foundation pit is reduced.The influence of pit in pit,especially adjacent pit in pit on foundation pit should not be ignored.The pit in pit steel protection cylinder quick support combination was designed,and the construction methods of welding and site sinking of steel shield tube are summarized.Based on the finite element method(FEM),the three-dimensional model of cooperative calculation and analysis model of deep foundation pit was established,and the three-dimensional space cooperative action state of multi-channel supporting system was simulated,and the weak parts of the whole foundation pit supporting system are found.The study can provide an effective analysis method for improving the overall stability of deep foundation pit with complex bracing system and accurately evaluating the influence of foundation pit excavation construction on the surrounding environment.