Abstract: The variations of ground settlement and shield boring parameters before and after shield stop of a metro shield section in water-rich gravel stratum are monitored and analyzed, and the ground settlement induced by shield body weight is calculated. The results indicate that: (1) The shield stop affects the settlement of the soil in front of shield body greatly, and the settlement rate is closely related to the stop time. (2) The soil settlement behind the shield body, which is mainly affected by the ground loss caused by shield construction, gradually becomes stable over time, and the shallower the depth of the soil layer, the earlier the settlement becomes stable. (3) For closely undercrossing construction of a new tunnel underneath an existing one, the impact of shield stop before undercrossing is greater than that after undercrossing. (4) Due to the large increase of the total thrust of jacks and upper pressure of the soil chamber, the ground settlement curve fluctuates first and then subsides, and the fluctuation range of deep settlement is significantly larger than that of surface settlement, which shows that shield stop in water-rich gravel stratum will amplify the disturbance effect on the adjacent deep soil, and the shield stop should be avoided as much as possible during the closely undercrossing construction.

Key words: EPB shield, water-rich gravel stratum, shield stop, ground settlement, boring parameters