某深基坑地下连续墙开挖变形有限元分析

Finite Element Analysis of the Underground Retaining Wall of a Deep Foundation Excavation

针对上海市某地铁车站端头井部分地下连续墙在开挖过程中的变形进行了三维有限元分析,对比了两种不同有限元模型下的墙体变形:一种方法采用三维实体单元模拟钢筋混凝土地下连续墙,采用郎肯主动土压力理论计算墙后土压力,坑内土视为弹簧单元,采用"m"法计算墙体位移曲线;另一种方法将墙体视为壳单元,考虑了土体-支护体系的共同作用,计算出墙体在开挖过程中的位移曲线。最终将两种不同方法计算结果与实测结果进行对比,结果表明该端头井段地连墙最大水平位移发生在最终开挖面以下约1m位置,总体变形曲线与实测曲线基本吻合。

3D finite element analysis was performed on the underground retaining wall in an end pit section of a deep foundation during its excavation. The retaining wall deformation was deduced with two different methods. In the first method the underground retaining wall was assumed as 3D element and the Rankine earth pressure theory was adopted to calculate the earth pressure behind the retaining wall. The soil in front of the wall was taken as spring element and the ＂m＂ method was adopted to calculate the deformation of the underground retaining wall. In the other method the retaining wall was assumed as shell element with considering the joint action of the retaining wall, soil and support structure. Finally the deformation curves were compared with the curve measured from the construction site. The largest horizontal displacement of the retaining wall occurred about 1 meter under the final excavation plane. The curves from the two methods and the curve measured from the construction site were similar.