Abstract:

Zhushikou station on No.7 line of Beijing Metro is a large mined station constructed by PBA method and its north heading is closely and parallel running under a sewage pipe with 1950mm diameter. As a result of the water in sewage pipe run quickly and deep as well as the leakage among pipe joints, there are many pools along pipeline, which may induce unpredictable geological risk to heading construction; and conversely the disturbance, collapse and ground deformation during north heading construction of Zhushikou station may also bring severe destroy to sewage pipe and result in high heading construction risk. Thus the interaction between sewage pipe and heading construction is a crux task for the successful construction of Zhushikou station. Then according to the construction experiences of Zhushikou station, the risk control technologies for underground urban projects below existing sewage pipes in adverse geological conditions are summarized and a new risk control theory is proposed in this paper. That is strengthening pre-grouting in tunnel and cutting water flow in sewage to install line for pipe as well as other assistance measures. This double risk control theory can provide references for similar projects construction.

Key words: mined tunnel project, risk source, collapse, settlement