考虑塑性发展系数的简化软土基坑回弹变形预测

Simplified Prediction of Springback Deformation in Soft Soil Foundation Pit Considering Plastic Development Coefficient

为了解决现有的基坑回弹变形计算方法所需参数较多、计算过程较为繁琐、工程应用上受到限制等问题,利用孔隙比和压缩变形量的关系推导出塑性发展系数β的表达式,根据卸荷比R对回弹变形量的影响,估算坑底回弹土层的计算深度,且忽略深大基坑中央土体应力分布的空间效应和坑底中部土体在开挖前及开挖后均为均匀的自重应力场,建立一种基于塑性发展系数β的回弹量估算方法。利用该法对上海市某挖深17.9 m的深大基坑中部回弹量进行估算,并与回弹实际监测值作比较,结果表明,可以用该方法估算回弹量;同时,分析了该方法的工程应用可靠性,并对预测效果修正提出了相应的建议。

The engineering application of present calculation methods for foundation pit＇ s springback deformation is limited due to a large number of required parameters and cumbersome calculation process. In this paper, the ratio of plastic deformation to total soil compression deformation was defined as the plastic development coefficient β and on this basis, a new practical estimation method for the springback deformation was proposed. The expression of β can be deduced by the relationship between void ratio and compression deformation. The calculated depth of re- bound soil can be estimated according to the influence of unloading ratio R on springback deformation. Ignoring the spatial effect of soil stress distribution in the center of deep foundation pit, and assuming that the gravity stress field of central pit bottom soil is uniform before and after excavation, we hence obtained the calculation method. The method was used to calculate the central springback deformation of a foundation By comparing calculated results with monitoring data, this method was proved to of prediction correction and engineering application were given. pit （ depth 17.9m） in Shanghai. be feasible, and recommendations