Abstract: In order to avoid the impact of ultra deep foundation pit support on surrounding buildings and reduce the settlement of surrounding buildings after the completion of support construction, a new foundation pit support construction technology is proposed using a proposed project near the entrance and exit of Daminggong West Station on Xi'an Metro Line 2 as an example. Install drilling interlocking piles around the foundation pit to form the foundation pit enclosure structure, and use an equal thickness cement soil mixing wall. Set up a support system at the longitudinal diagonal of the ultra deep foundation pit to further protect the adjacent residential buildings. Based on the interlocking pile, the prestressed anchor cable installation is completed through four steps: drilling, anchor cable installation, grouting, and anchor cable tension, to strengthen the foundation pit support structure. Building a super deep foundation pit water stop curtain based on the double-sided overlap milling construction method to complete the overall construction of foundation pit support. The monitoring results show that five and a half months after the construction of ultra deep foundation pit support, the maximum settlement value of adjacent buildings is only 7.6 mm, which meets the requirements of foundation pit support construction.

Key words: existing buildings, ultra deep foundation pit, support structure, bored interlocking piles, water stop curtain

摘要： 为避免超深基坑支护对周边建筑的影响,减少支护施工完成后周边建筑沉降,以西安市地铁二号线大明宫西站1号出入口附近的一个拟建工程为例,采用一种新的基坑支护施工技术。在基坑四周布置钻孔咬合桩,组成基坑围护结构,并采用等厚度水泥土搅拌墙,在超深基坑的纵向对角处设置支撑体系,进一步保护紧邻既有住宅建筑。以咬合桩为基础,通过钻孔、锚索安装、注浆、锚索张拉4个环节完成预应力锚索安装,加固基坑支护结构。依托双侧搭接套铣施工成墙模式,搭建超深基坑止水帷幕,完成基坑支护的整体施工。监测结果显示:超深基坑支护施工后五个半月,邻近建筑物最大沉降值仅为7.6mm,满足了基坑支护施工要求。

关键词: 既有建筑, 超深基坑, 支护结构, 钻孔咬合桩, 止水帷幕