Abstract: Tunnel engineering is a linear-type project. It is a common working condition for shield tunneling to successively penetrate sandy cobble strata and sandy strata. To clarify the influence of soil properties on the ground response during the construction of shallow-buried shield tunnels, shield tunneling model tests were sequentially conducted in sandy cobble strata and sandy strata. Then, from the perspectives of shield tunneling mechanical parameters, ground settlement curves, and face stability, the similarities and differences in the ground response during tunneling in these two types of strata were analyzed. The results show that soil properties have a significant impact on the ground response during the construction of shallow - buried shield tunnels. The shield tunneling mechanical parameters in sandy cobble strata are all greater than those in sandy strata. Moreover, both the cutterhead torque and the screw conveyor torque are negatively correlated with the rotation speed of the screw conveyor. The symmetry axes of the ground surface settlement curves in both strata deviate from the tunnel centerline. When the shield cutterhead rotates clockwise, the symmetry axis is located on the left side of the tunnel centerline, and the deviation in sandy cobble strata is significantly larger than that in sandy strata. In sandy cobble strata, the amount of excavated soil from the tunnel face shows a two - stage change pattern of "linear increase - constant" over time, and the soil in the stratum exhibits a local instability failure mode. In sandy strata, the amount of excavated soil from the tunnel face shows a continuous linear increase over time, and the soil in the stratum presents an overall instability failure mode. Additionally, the center of the ground surface collapse is located in the left - front area of the shield cutterhead.

Key words: shield tunnel, ground construction response, model test, sandy cobble strata, sandy ground