Abstract:  In order to study the ground settlement caused by subway shield construction, firstly,based on Biot consolidation theory, a visco-elastic-plastic constitutive relation of soil mass and the dynamic change of soil permeability is considered, a three-dimensional fully coupled numerical model is established. Then, taking the shield construction section from Maluowei Station to Shitang Park Station of Jiangbei New District of Nanjing Metro Line 11 as an example, the settlement of the shield section is simulated and predicted, and the model is calibrated. Finally, the model is used to simulate and predict the ground settlement law caused by shield excavation, and the parameter changes of soil above the shield arch and under the shield bottom are simulated. The results show that the measured ground settlement is in good agreement with the calculated values, and the model is reliable. Taking the second section of the model as an example, the settlement of the eastern line is in the range of 52.41-54.52 mm, and the settlement of the western line is in the range of 53.28-55.60 mm. The settlement of shield tunnel in the eastern line is symmetrically distributed in the center of the tunnel axis, and the cumulative ground settlement of the tunnel in the western line is larger between the axes after tunnel excavation. With the progress of excavation, the porosity, permeability coefficient and Poisson’s ratio of the soil above decreased, and the deformation modulus increased, while the change of the soil below was opposite.

Key words: ground settlement, Bio-consolidation theory, shield construction, three-dimensional full coupling；subway；tunnel