Analysis of the Aging Law of Surface Uplift Caused by Deep Shield Excavation in Soft Soil

The surface settlement caused by the excavation of the shield tunnel in the deep stratum of the soft soil area is mainly influenced by the value of the construction parameters in the excavation process and the matching with the stratum parameters. Different from the excavation of shallow strata, the surface disturbance caused by the excavation of deep strata in soft soil is significantly affected by the long-term creep time-effect of soft soil. Therefore, in the same section of deep strata in the soft soil area of Shanghai, the actual measurement and analysis research was carried out by adjusting the construction parameters of deep stratum shield. When the shield cutter head approaches and passes through the monitoring section, the jacking speed and soil chamber pressure were adjusted. When the shield tail is out of the ground, the grouting parameters were adjusted to obtain the time-effect law of surface settlement caused by the construction disturbance of deep-buried shield under the same site conditions of soft soil. By analyzing the differences in surface uplift and subsidence, it is concluded that the short-term surface settlement caused by shield excavation in deep soft soil is mainly due to the excess pore water pressure caused by soil tank pressure and tunneling speed, while the long-term surface settlement value is mainly determined by the creep effect controlled by the grouting volume at the shield tail. The main and secondary order of influencing factors of construction parameters on surface settlement is grouting volume, soil chamber pressure, and excavation speed.