河道偏压对地铁基坑临河侧变形的影响

Effect of river deflection on deformation of river side of metro pit

为探究基坑临河侧在河道偏压作用下基坑的变形特征,以北京地铁3号线基坑工程典型断面为研究对象,利用有限元软件RS3,建立以河道距离为变量的三维数值模型,对比分析现场实测数据与模拟结果,并从多角度分析墙体水平位移及地表变形两项评价指标。结果表明:墙体上部对偏压反馈更明显,并且会出现向河道侧倾覆现象;当河道间距由23 m减小至8 m,墙体最大水平位移增量随间距减小而增大,由2.86%升至6.37%,倾覆值由7.39%增大至11.68%,且倾覆值可达最大水平位移的67.41%;与常规基坑相比,地表变形随开挖深度的增加呈现先沉降后隆起趋势,河道间距每减少1 m隆起值增加约0.6 mm。

This paper aims to explore the deformation characteristics behind the foundation pit near the river under the action of the biased pressure of the river.The study by taking the typical section of the foundation pit of Beijing metro line 3 as the object involves building a three-dimensional numerical model with river distance as variable by using finite element software RS3;comparing the field measured data with the simulation results;and analyzing the evaluation indexes of the horizontal displacement of the wall and the surface deformation from multi-angles.The results show that the upper part of the wall has more apparent influence on deflection and overturns towards the river side;When the river spacing is reduced from 23 m to 8 m,the horizontal displacement maximum of the wall increases with the decrease of spacing from 2.86%to 6.37%;the overturning value increases from 7.39%to 11.68%,and the overturning value can reach 67.41%of horizontal displacement the maximum;Compared with the conventional foundation pit,the surface deformation presents the rule of first settlement and then uplift with the increase of excavation depth,and the uplift value increases by about 0.6 mm with the decrease of channel spacing by 1 m.