地铁深基坑开挖对邻近建筑物影响分析

为研究深基坑开挖对邻近建筑物的影响特征并评价其安全性,以厦门市某车站深基坑工程为例,通过构建三维有限元模型,考虑土体小应变刚度行为以及基坑-地基-基础-上部结构共同作用,计算基坑开挖引起邻近建筑物的变形值,并将柱底支座变位作为上部结构的强迫位移施加到上部结构上,然后进行结构内力分析和构件配筋验算,评价邻近建筑物的安全。研究表明:邻近建筑物越靠近基坑部分受基坑开挖影响越大,基坑开挖后,邻近建筑物结构变形主要表现为沉降和指向基坑的水平位移,结构最大水平位移为6.6 mm,自顶部向下逐渐减小,即结构发生微量倾斜;邻近建筑物地下室以沉降变形为主,主要受影响区域约为基坑围护墙后3倍的基坑开挖深度范围,沉降急剧变化区域约为1.5倍基坑开挖深度范围,地下室最大沉降为15.9 mm;受到邻近基坑开挖影响,上部结构虽然因支座变位产生内力重分布,但经检算认为整个结构仍然安全可靠。

Study on the Impact of Metro Deep Foundation Excavations onNeighboring Buildings

This paper aims to study the impact of deep excavation on neighboring buildings and evaluate its safety. Taking the deep foundation excavation project of a metro station in Xiamen City as an example, a three-dimensional finite element model was built. With the consideration of the small-strain stiffness behavior of soils and the interaction of the pit, the foundation base, the foundation and the superstructure, the deformation of neighboring buildings caused by deep foundation excavation was calculated. The deflection at the bottom of the column was exerted on superstructure as its forced displacement to calculate the structural internal force and check the reinforcement of components. Then, the safety of neighboring buildings was evaluated. Result shows that the closer the neighboring buildings are to the excavation, the greater the impact is. The deformation of neighboring buildings shows settlement and horizontal displacement to the foundation pit after excavation. The neighboring building structure inclines slightly to the foundation pit, with a maximum horizontal displacement of 6.6 mm occurring at the top of the building and decreasing gradually to the bottom. The structural settlement is the prominent response of the basement to the excavation. The affected distance is about 3 times of foundation depth from the support walls, and the severe settlement area is in the range about 1.5 times of foundation depth to the foundation support structure. The maximum settlement of the basement is 15.9 mm. Under the impact of neighboring foundation excavation, the internal force of the superstructure redistributes due to support dislocation, but the whole structure is testified to be safe and reliable.