地铁车站基坑半幅盖挖法施工监测及分析

结合洛阳地铁1号线武汉路站深基坑半幅盖挖法施工过程,对支护结构和周边建筑变形进行监测分析,结果表明,半幅盖挖法所形成的不对称结构使基坑两侧地连墙水平变形和地面竖向变形特征均有不同;基坑明挖侧地连墙的水平位移较为一致,而盖挖侧的变化无一致规律性;地连墙水平位移最大值出现在基坑开挖底面以上0.22~0.42 H处,未出现在基坑开挖深度以下;盖挖侧地面变形量和附近建筑的竖向位移小于明挖侧,说明盖挖侧顶板对周围变形有抑制作用;基坑周边的施工荷载对围护结构的变形特征、混凝土支撑的轴力等均有明显影响,因此施工过程中应严格控制基坑周边出现超载。

Construction monitoring and analysis of by-width cover&cut method for underground station foundation pit

Taking into consideration of the construction process of the deep foundation pit of Wuhan Road Station of Luoyang metro line 1,this paper monitors and analyzes the deformation of the supporting structure and the surrounding buildings.The results show that the asymmetric structure formed by the half width cover cut method makes the horizontal deformation of the diaphragm wall on both sides of the foundation pit different from the vertical deformation,the horizontal displacement of the diaphragm wall on the open excavation side of the foundation pit is relatively consistent,while the deformation on the cut and cover side is relatively small.The results show that the maximum horizontal displacement of diaphragm wall appears at 0.22~0.42 h above the bottom of foundation pit excavation,but not below the excavation depth of foundation pit,the ground deformation and the vertical displacement of nearby buildings on the cut and cover side are less than those on the open excavation side,which indicates that the roof on the cut and cover side has an inhibitory effect on the surrounding deformation,the construction load around the foundation pit has an impact on the deformation characteristics of retaining structure and the stability of concrete support.Therefore,the overload around the foundation pit should be strictly controlled in the construction process.