城市隧道基坑地下连续墙变形特性研究

Characteristic of diaphragm wall deflection due to deep excavation of municipal tunnel

为了研究城市隧道深基坑开挖引起的地下连续墙墙体变形规律,对南京纬三路过江通道工程隧道基坑监测结果进行了以下几方面的统计分析:基坑开挖引起的墙体侧移的时空变化特征,墙体最大侧移位置的特征,有支撑开挖下地下连续墙最大侧移简易预估模型(KJHH)对地下连续墙最大侧移进行预估的实用性。研究表明:随着基坑开挖深度的增加,地下连续墙变形逐渐变为明显的"胀肚型",平均值为0.144%He(He为基坑开挖深度),最大侧移随着开挖深度的增加而增大;地下连续墙最大侧移埋深出现在开挖面稍下一点位置,产生这一现象的主要原因是本基坑中淤泥质黏土软弱土层一般处于开挖深度的中上部,开挖这些土层会在开挖面产生较大的变形;采用KJHH简易模型预估得到的地下连续墙最大侧移和实测值接近,说明KJHH简易模型可以有效地预估本工程地下连续墙的最大侧移。

In order to clarify the law of wall deflection due to deep excavation of city tunnel. The pit monitoring results of Nanjing Wei Three-Road river tunnel foundation pit were analyzed as follows： the characteristics of temporal and spatial variation of wall deflection caused by excavation of foundation pit,the maximum deflection of wall,and the utility of simplified model to estimate the maximum deflection of wall（ KJHH）. The results show that with the increase of the depth of excavation,the wall deflection gradually shaped into a bulging belly type,with a mean value of about 0. 144% He（Heis the excavation depth）; Moreover then increased with the increase of the excavation depth. The maximum wall deflection position mainly on excavation face was slightly below to the point position. The main reason of this phenomenon was the silt clay soft soil layer usually is located the upper part of the depth of excavation,excavation of these soil can produce large deflection in excavation face. The predicted values of KJHH simplified model are very close to the observation values. The result proves that the KJHH simplified model can effectively predict the maximum wall deflection.