内坑坑背系数对坑中坑基坑变形影响的敏感性分析

以苏州某地铁换乘站坑中坑为基本模型,采用土体卸载条件下的HS有限元模型,系统研究内坑坑背系数β对坑中坑基坑支护结构和基坑土体变形的影响。结果表明:外墙侧移随β增大而增大,β由0.125增大到0.75,外墙最大侧移增加34.08%,同时最大侧移位置下移了2.0 m,β对外坑底面附近以上的外墙墙身侧移影响较小,而对坑底以下侧移影响显著。内墙侧移随β增加而显著增大,β由0.125增大到0.75,内墙墙身最大侧移增加153.95%,最大侧移位置随β增大而下移,内墙墙顶竖向位移随β增大而减小。内坑坑底隆起、外坑坑底隆起随β增大而微弱减小,外坑坑背沉降总体随β增大而增大,但不同β值对应的沉降曲线相似。

Sensitivity Analysis of Impact of Internal Depth to Bottom Width Ratio on Deformation of Pit in Pit

Adopting Hardening-Soil finite element model with unloaded soil,this paper addresses the influence of the ratio β of internal depth to bottom width on the retaining structure and the deformation of the pit in pit based on the basic model of the pit of a metro transfer station in Suzhou. The results show that the lateral deformation of external wall increases with growing β and maximum value of 34. 08% is added when β increases from 0. 125 to 0. 75,meanwhile the location moves downward 2. 0 m; β has little effect on the lateral deformation near the above external pit bottom,but remarkably on the part under the pit bottom. The lateral deformation of internal wall increases obviously with growing β and the maximum value of 153. 95% is added when β increases from 0. 125 to 0. 75,meanwhile the location moves downward,and the uplift of the internal wall reduces as well. The bottom uplift of the internal and external pit decreases slightly with growing β,while the settlement of the internal depth to bottom width tends to increase with growing β,but the settlement curves corresponding to different β are similar.