基于离心试验的承压水基坑变形稳定影响因素

针对上海地铁M8线黄兴路车站深基坑,采用离心模型试验研究第⑥硬土隔水层缺失与否、基坑开挖深度和承压水头高度等因素对承压水基坑变形稳定的影响.试验研究结果显示:(1)不论存在或缺失第⑥隔水层,基坑最大变形均随着开挖深度和承压水头的增加呈非线性增大,开挖深度影响最大的是坑周地面沉降和连续墙墙脚位移,承压水头影响最大的是连续墙墙脚位移和坑底隆起变形.(2)不论存在或缺失第⑥隔水层,开挖深度对基坑变形影响的敏感性比承压水头大.(3)基坑开挖深度较小、承压水头较低时,第⑥隔水层缺失与存在相比,基坑最大变形差异较小;随着开挖深度和承压水头的增大,两者变形的差异越来越大,缺失第⑥隔水层不利于基坑稳定.

Centrifuge Model Experimental Study on Influence Factors of Deformation Stability for Confined Water Foundation Pit

For the deep foundation pit of Huangxing road station in Shanghai metro line M8,the centrifuge model testing was used to study No.6 stiff soil-aquiclude,excavation depth and confined water head influence on deformation stability of the pit.The results show that,(1) whether there is No.6 aquiclude or not,the biggest pit deformation enlarges nonlinearly with the increase of the excavation depth and the confined water head,therefore,the excavation depth has great influence on ground settlement around the pit and displace of the diaphragm wall feet,and the confined water head has great influence on the displace of the diaphragm wall feet and uplift deformation at the bottom of the pit,(2) whether there is No.6 aquiclude or not,the excavation depth sensitivity to the pit deformation is bigger than the confined water head's,(3) while the pit excavation depth is shallow and the confined water head is low,the difference of the biggest deformation is little for the pit between with No.6 aquiclude and without No.6 aquiclude,but with the increase of the pit excavation depth and the confined water head,the difference of them become obviously large,and lack of No.6 aquiclude is not of benefit to the pit stability.