北京地铁某车站明挖基坑施工监测分析

对北京地铁某车站明挖基坑施工跟踪监测,及时掌握基坑变形、支撑内力的变化动态,分析了施工过程中支护结构位移与内力的变化特征,并指导施工确保基坑稳定。测试表明：a)围护结构水平位移随工期的延续而增加,基坑开挖完成后逐渐趋于稳定,位移在第2道支撑处最大,围护结构底部位移较小；b)第1道钢支撑的轴力明显大于第2道和第3道支撑的轴力,c)在基坑阳角处斜钢支撑的轴力比其他位置钢支撑的轴力要大得多。

Construction Monitoring Analysis for an Open Excavated Foundation-pit of a Subway Station in Beijing

A field monitoring programme is carried out for the open-excavated project of a subway station in Beijing,the trends of the displacements and the inner forces are under control,and the change of characteris- tics of displacements and inner forces in the retaining structure during the construction is analyzed.The neces- sary engineering measurements are taken to keep the stability of the excavated foundation pit.There are sev- eral monitoring conclusions as follows:a)the horizontal displacements of retaining structure increase with the construction duration and tend to be ltable gradually after the foundation-pit excavation is completed,The largest displacement appears on the second layer steel support tube and the displacement is the smallest in the bottom of retaining structure;b)the axial forces on the first layer steel-support tube significantly greater than those of the second and the third layers;and c)the axial forces on the diagonal steel-support tubes in the out- side corner of the foundation-pit are much greater than those of the others.