北京地铁四号线宣武门站下穿运营车站沉降控制综合施工技术

Comprehensive Construction Techniques for Settlement Control of Xuanwumen Metro Station Crossing Underneath Existing Metro Station on No.4 Line of Beijing Metro

针对新建地铁车站下穿既有运营车站的工程特点,以控制沉降为核心,分别从管棚超前支护、开挖与初期支护、结构二次衬砌3个环节阐述宣武门车站下穿运营车站的沉降控制综合施工技术。大管棚施工采用国内先进的夯管工艺,配以袖阀式及分段后退式注浆技术措施;开挖前采用帷幕注浆,开挖、初期支护及二次衬砌期间采用全过程跟踪补偿注浆;开挖与初期支护期间采取加强措施改善平顶直墙结构的不利受力状态;二次衬砌创造性地采取分幅施作方案,以部分二衬结构代替支撑。通过实施一系列的技术措施,最终使既有运营车站的结构最大沉降仅为6.78mm,完全满足设计要求。

Xuanwumen Metro Station on No. 4 Line of Beijing Metro crosses underneath existing Metro station, therefore settlement control is the key point in the construction of this project. This paper presents the comprehensive construction techniques for settlement control in construction of Xuanwumen Station from the following three aspects： advance pipe- roof support, excavation and primary support, and secondary support lining of tunnel structure. Nationally-advanced pipe-ramming construction technology assisted by sleeve-valve type and retrograde grouting measures is adopted for large pipe-roof construction. Curtain grouting is executed before excavation, and full process tracing and compensation grou- ting is executed during excavation, primary support and secondary lining. Reinforcing measures are taken to improve the unfavorable force-bearing conditions of the structure with horizontal roof and straight wall during excavation and primary support. The secondary lining is installed breadth by breadth so as to make some of the secondary lining structures to support the tunnel. Due to these comprehensive technical measures1 the settlement of the existing Metro station has been put under effective control. The maximum settlement of the existing Metro station is only 6.78 mm, which completely satisfy the design requirement.