Abstract:

When the mined metro station is limited by the environmental conditions, the structure of flat roof and straight
wall has to be adopted. Hence, in order to ensure the safe implementation of the station structure, the pipe-roof PBA
method can be used for construction. In order to form a strong supporting structure which can withstand the soil load, the
transverse large-diameter dense-row pipe-roof is set up along the top of the roof structure of the station by using the pilot
tunnel of the upper layer of the station, and the rest of the structures are constructed under the protection of the piperoof.
The construction procedure and technological characteristics of the pipe-roof PBA method adopted in You′anmenwai
Station of Beijing Metro Line 19 are introduced. The key technologies of the pipe-roof PBA method under complex
environmental conditions, i. e. pipe-roof construction, pilot tunnel excavation, pile driving and arch buckling, are
analyzed. The technical points in design and construction phase are clarified. Meanwhile, the construction monitoring
data of the station are analyzed, and the analytical results show that: (1) the pipe-roof construction and the pilot tunnel
excavation are the key processes of the ground settlement caused by the pipe-roof PBA method; (2) the pipe-roof PBA
method has little influence on the surrounding environment and surface settlement, which is suitable for the construction
of mined station with super shallow buried, large cross-section and complex geological conditions.

Key words: mined metro station, pipe-roof PBA method, pipe-roof construction, pilot tunnel excavation, arch
buckling, construction monitoring