降水开挖作用下地铁基坑变形的三维数值分析

Three-dimensional Numerical Analysis of Metro Foundation Pit DeformationConsidering the Effect of Dewatering and Excavation

为研究地铁基坑施工过程中,不同特征位置处的基坑变形响应差异,本文以某地铁车站基坑工程为研究背景,利用数值计算软件建立3D数值模型进行模拟分析。模拟值与实测值吻合良好,验证了数值模拟的准确性。在此基础上考虑不同施工工况及开挖深度,分析标准段和端头井位置处基坑地连墙侧移和地表沉降的变化规律。结果表明:地连墙侧移形式均为“鼓肚”型,地表沉降形式均为“凹槽”型;相较于标准段,端头井位置处的基坑地连墙侧移和坑外地表沉降均更小;相较于降水开挖,干砂开挖引起的基坑地连墙侧移和坑外地表沉降均更小;随着开挖深度的增大,基坑地连墙侧移和坑外地表沉降均显著增大。

In order to investigate the difference in deformation response at different typical locations during the construction of a subway foundation pit,a three-dimensional numerical model was established by using finite element software based on the foundation pit project of a certain subway station.The simulated values are consistent with the measured values,verifying the accuracy of the numerical simulation.Different construction conditions and excavation depths were taken into consideration according to the above numerical model,and the lateral movement of diagram wall and surface settlement at the middle section and the end well were analyzed.The results show that the lateral movement patterns of diagram wall is bulging-type,and the surface settlement patterns is groove-type;Compared with the middle section,the lateral movement of diagram wall and surface settlement outside the pit at the end well are smaller;Compared with dewatering and excavation,dry sand excavation causes smaller lateral movement of diagram wall and surface settlement outside the pit;As the excavation depth increases,the lateral movement of diagram wall and the surface settlement outside the pit increase significantly.