Abstract:

The Guojilu StationNorth Huanchenglu Station shield bored tunnel on Zhengzhou Metro Line No. 2 is located in waterrich fine silty sand strata and crosses underneath 3 existing pressured watersupply concrete pipelines. In order to meet the settlement control requirements, the construction risk of soil deformation induced by heterogeneous settlement is analyzed. The cutterhead structure type, cutterhead support type and injection points of ground conditioning agent on cutterhead are the main factors for ground settlement. Some suggestions are propased as follows: 1) The shield cutterhead structure type and related devices are very important. 2) Rational construction parameters and technologies are necessary. The monitoring results show that the maximum pipeline settlement can meet the risk control requirement.

Key words: Zhengzhou Metro, waterrich fine silty sand strata, pressured pipeline, shield type selection, cutterhead structure, ground conditioning, monitoring