Abstract:

Ground surface settlement is one of the most important parameters that should be well controlled in shield tunneling. During the construction of Line 1 of Shijiazhuang Metro, the settlement on some specific days reaches the alert value, however, the accumulated settlement value does not reach the alert value, although the shield boring parameters meet the design requirements. In the paper, the causes for the ground surface settlement are analyzed in terms of excavation chamber pressure, simultaneous grouting, grout performance and ground stability, with the data of the running tunnel from Stadium station to Beisong station measured on June 15, 2014 as examples. Finally, the ground settlement under the fine silt sand strata, finemedium sand strata and mediumcoarse sand strata in Shijiazhuang are analyzed. 

Key words: Shijiazhuang Metro, shield, surface settlement