坑趾系数对坑中坑基坑变形影响的敏感性分析

采用土体卸载的HS有限元模型研究地铁换乘站坑中坑坑趾系数α对支护结构和土体变形的影响。结果表明:外墙最大侧移随坑趾系数增大而显著减小,侧移位置上移,α从0.25增加到1.5,外墙最大侧移从44.96 mm减小到30.71 mm,侧移深度从18.875 m上移到16.0 m;内墙侧移随α增大而减小,α从0.25增加到1.5,内墙最大侧移从45.74 mm减小到24.48 mm,内墙墙顶竖向位移随α增大而增大;内坑坑底在内墙10 m范围内出现显著隆起区,最大隆起量随α增加而减小,隆起区外的隆起值稳定保持在90 mm左右;外坑坑底隆起随α增大而增大,最大隆起位置出现在内墙外侧边缘,外墙内侧边缘的挤压隆起随α增大而增大,隆起范围和隆起量都较为显著;外坑坑背沉降曲线相似,沉降量随α增大而减小。

Sensitivity Analysis of the Influence of Pit Toe Coefficient on Pit in Pit Deformation

Adopting Hardening-Soil finite element model based on unloading,the influence of pit toe coefficient α on the retaining structure and the deformation of the excavation was studied based on the basic model of the pit of a metro transfer station.The results show that the maximum lateral deformation of external wall reduces obviously with the ratio growing,meanwhile the position moves upward,the maximum lateral deformation of external wall reduces from 44.96 mm to 30.71 mm,and the position moves upward from 18.875 m to 16.0 m,with the ratio increasing from 0.25 to 1.5,the uplift of top increases with the ratio grows.The maximum lateral deformation of internal wall reduces obviously with the ratio growing,the value reduces from 45.74 mm to 24.48 mm,the vertical deformation of the top internal wall increases with the ratio growing.Significant uplift area appears at about 10m near the internal wall,the maximum uplift reduces with the ratio growing.The uplift maintains 90mm at outside of significant uplift area without influence of the ratio.The uplift of external pit bottom increases with the ratio growing,and the maximum uplift position appears near the outside of internal wall.All curves of ground settlement of external pit are similar,the settlement reduces with the ratio growing.