Abstract:

 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 grouting 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 measures, the settlement of the existing Metro station has been put under effective control. The maximum settlement of the existing Metro station is only 6.78mm, which completely satisfy the design requirement.

Key words: Xuanwumen Metro Stationcrossing underneath existing Metro stationsettlement control