The responses of three heritage buildings to a deep excavation constructed by top-down method in Shanghai soft clay are presented. The subsurface conditions, initial state of the adjacent buildings, supporting system, construction procedure, and field monitoring were summarized. Analysis of the monitored data revealed that the construction activities (including diaphragm wall installation, pile installation, and ground water lowering) prior to the excavation had significant impacts on the settlements of the buildings. Characteristics of the building deformation caused by these construction activities nearly remained unchanged through the excavation stage. Factors such as distance to the excavation, stiffness of the structure, and the type of foundation may affect the building performance during excavation. Three-dimensional deformation behavior of the excavation had significant impact on the building performance. Analysis of the settlement profiles of the buildings reveals both hogging and sagging of the buildings. The maximum distortion of the buildings was 1/667. However, no further development of the initial cracks in the buildings was observed, indicating effectiveness of the top-down method and the relevant protection measures.%分析上海软土地区的一个全逆作法深基坑施工对周边三幢历史保护建筑物的影响.简要地介绍该工程的地质条件、基坑施工前周边建筑物的现状、基坑围护方案、施工工况与监测情况.对监测结果的分析表明基坑开挖前的连续墙施工、工程桩施工和降水等前期工程活动显著地影响周边建筑物的沉降,且此阶段的沉降奠定了建筑物的变形形态.建筑物沉降形态与建筑物各点距基坑的距离、建筑物本身的上部刚度和基础形式密切相关,且基坑变形的三维效应显著地影响建筑物的沉降形态.分析建筑物的上拱和凹陷变形.建筑物最大倾斜量为1/667,基坑施工过程中建筑物的原有裂缝基本未见进一步发展,表明本工程的逆作法方案及相关保护措施有效地保证了周边建筑物的安全.
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