Abstract：Taking the overlapping tunnel of Shenzhen Metro Phase I project for example，the FLAC3D (fast Lagrangian analysis of continua)codes was adopted to model the stratum 3D deformation regularity caused by four-step shallow tunnel construction method(STCM). By comparing with the in-situ monitor data of the test section，the value of stratum deformation caused by tunnel excavation or seepage of groundwater was obtained，and the environment control standard of general stratum is differentiated from that of aqueous sand stratum. According to the standard，the maximum value of ground settlement of general soft stratum of Shenzhen Metro is 60 mm and that of aqueous sand stratum is 120 mm. For some position with high standard of ground settlement control requirement，second reinforcement measures are taken to decrease stratum deformation，such as ground vertical jet grouting reinforcement which costs more than the general reinforcement measures. The technique has been applied successfully in Shenzhen Metro Phase I project. The research result will provide reference for controlling the construction environment of the construction of Shenzhen Metro and the project with the similar stratum. It will also offer theoretical reference for the application of shallow tunnel construction method(STCM) to aqueous soft sand stratum.
