深基坑地下连续墙与环形支撑组合支护体系变形特性分析

Analysis of Deformation Characteristics of Combined Support System of Diaphragm Wall and Ring Support of Deep Foundation Pit

以天津地区环绕并紧贴既有思源道地铁车站的深大异形基坑工程为背景,对开挖过程中环形支撑、地下连续墙等支护结构以及基坑侧壁后部土体的变形和受力情况进行了全程监测。结果表明:1)地下连续墙水平位移随着开挖的进行而逐渐增大,且水平位移均指向基坑内侧;地下连续墙顶部的竖直位移变化规律为先沉降后隆起。2)环形支撑体系的构件轴力随着开挖过程的进行而规律性地变化,一般表现为先增大、后稳定,并会由于开挖步骤和构件位置的不同而表现出不均匀性。3)基坑侧壁后部土体的水平位移随着开挖深度的增大而增大,沿竖直方向表现为"凸"字形特征,且最大水平位移点的空间位置逐渐向下移动。监测与分析表明,对于天津地区类似的深大异形基坑工程,地下连续墙和环形支撑的组合结构方式是一个优选方案。

Taken the deep and large special-shaped foundation pit project which surrounds and clings to the existing Siyuan Road subway station in Tianjin as an example, the deformation and stress of supporting structures such as ring support, diaphragm wall and the rear soil of the side wall of foundation pit were monitored during the whole excavation.The results show that: 1) The horizontal displacement of diaphragm wall increases gradually with the excavation,and the horizontal displacement points to the inside of foundation pit. At the top of diaphragm wall, the vertical displacement settlement firstly and then uplift. 2) The axial force of the ring supporting system changes regularly with the excavation, generally increases firstly and then stabilizes. It also shows inhomogeneity due to different excavation steps and component positions. 3) The horizontal displacement of rear soil of the side wall increases with the increase of excavation depth, and it appears as "convex" shaping along vertical direction, and the location of maximum horizontal displacement gradually moves downwards. According to monitoring and analysis, the combined system of diaphragm wall and ring supporting structure is an optimum scheme for similar projects in Tianjin.