（1 北京维拓时代建筑设计股份有限公司， 北京 100025； 2 建研地基基础工程有限责任公司， 北京 100013）

［摘要］某既改项目新增一层下沉广场，下沉广场四周均是既有建筑的地下室。经过多方论证，采用逆作法施工下沉广场能最大程度节省工期，提高业主周转效率。介绍了该工程逆作法施工的设计及要点；重点描述了采用支护和挡墙一体设计的桩墙来代替地下连续墙作为基坑支护的设计做法以及采用钢筋混凝土复合柱代替型钢格构柱的设计做法，此做法的施工难度低于传统施工做法；并介绍了采用钢管桩对原有结构柱进行托换的技术。

［关键词］逆作法； 支护挡墙一体； 柱托换； 灌注桩

中图分类号：TU354文献标识码：A文章编号：1002-848X(2019)16-0055-04

Design and application of top-down construction method in a reconstructed underground square project

Li Hongqiu1, Xu Yue1, Wu Zengliang1, Li Qinrui2

(1 Beijing Victory Star Architectural & Civil Engineering Design Co., Ltd., Beijing 100025, China;2 Carb Foundation Engineering Co., Ltd., Beijing 100013, China)

Abstract:A reconstructed underground project was surrounded by the basement of the current buildings and a new layer of an underground square was added. After much argument and consultation, top-down construction method was used in order to reduce the period of construction and increase owner′s turnover ability. The key points of the top-down construction method used in the project were introduced. The design method of using  dual-purpose pile wall for supporting and retaining wall to replace the underground diaphragm wall for foundation pit supporting was emphatically described. The design method of the reinforced concrete composite column was emphatically described to replace the steel lattice column. The construction difficulty of this method was lower than that of traditional construction method. The technology of using steel pipe piles to transfer the original structural columns was introduced.

Keywords:top-down construction method; dual-purpose pile wall; column transfer; bored pile

通讯作者：徐越，硕士，工程师，Email：xuyue@vtjz.com。