软土地铁深基坑小尺度盆式挖土法研究与应用

经过多年的发展,地铁车站条形基坑根据时空效应理论形成了斜面分层、分段、分块的施工方法,但细化到每块土方如何开挖支撑,目前尚未有相关研究。为此,借鉴大型软土基坑盆式挖土法,根据软土的力学特点和地铁车站基坑施工的时间、空间尺度,结合条形基坑的实践操作特点,提出软土地铁深基坑的小尺度盆式挖土法。通过数值计算对盆边土预留宽度、等待时间等施工参数的敏感性展开分析,并分别就斜撑区域与对撑区域细化具体施工工艺。实际工程应用的结果表明,小尺度盆式挖土法可以有效地控制基坑变形,施工参数具有可操作性,值得推广和应用。

Study and Application of Small Scale Basin Method for Deep Foundation Pit of Metro in Soft Soil

After years of development, the strip foundation pit of subway station has formed the construction method of layered, segmented, and divided slopes based on the theory of space-time effect.However, few detailed research has been done on how to excavate and support each earthwork.To this end, learning from the large-scale soft soil foundation pit basin excavation method, according to the mechanical characteristics of soft soil and the time and space scales of subway station foundation pit construction, combined with the practical operation characteristics of strip foundation pits, a small-scale basin excavation method for subway deep foundation pits in soft soil area was proposed.Through numerical calculation, the sensitivity of construction parameters such as the reserved width and waiting time of retained soil was analyzed, and the specific construction process was detailed for the diagonal bracing area and the counter bracing area.The actual engineering application results show that the small-scale basin excavation method can effectively control the deformation of the foundation pit, and the construction parameters are operable, which is worthy of popularization and application.